Title of Invention	A LEAD-BARIUM-STRONTIUM-TITANATE COMPOUND [PB1-X-BA0.5X-SR0.5X-TIO3] AND A METHOD OF FABRICATING THE SAME.
Abstract	[000124] The present invention provides a lead titanate based compound, particularly a ferroelectric Lead-Barium-Strontium-Titanate compound having a chemical composition expressed by compositional formula, Pb1.xBao.5xSr().5XTi03, where x takes values greater than 0.0 5 and less than 1.0 for use in transducers as sensing element and in capacitors as a dielectric material, whereas in data storage devices as a memory dement, wherein the lead barium strontium titanate compound is characterized by having high dielectric constant, low dielectric loss, low porosity, high mechanical strength and remnant polarization. A method of fabricating the ferroelectric lead parium strontium titanate compound is also disclosed. 10

Title of Invention

A LEAD-BARIUM-STRONTIUM-TITANATE COMPOUND [PB1-X-BA0.5X-SR0.5X-TIO3] AND A METHOD OF FABRICATING THE SAME.

Abstract

[000124] The present invention provides a lead titanate based compound, particularly a ferroelectric Lead-Barium-Strontium-Titanate compound having a chemical composition expressed by compositional formula, Pb1.xBao.5xSr().5XTi03, where x takes values greater than 0.0 5 and less than 1.0 for use in transducers as sensing element and in capacitors as a dielectric material, whereas in data storage devices as a memory dement, wherein the lead barium strontium titanate compound is characterized by having high dielectric constant, low dielectric loss, low porosity, high mechanical strength and remnant polarization. A method of fabricating the ferroelectric lead parium strontium titanate compound is also disclosed. 10

Full Text	FORM 2 The Patent Act 1970 (39 of 1970) & The Patent Rules, 2005 COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13) TITLE OF THE INVENTION "A LEAD-BARTUM-STRONTIUM-TITANATE COMPOUND [Pb1-XBa0.5XSr0.5XTio3] AND A METHOD OF FABRICATING THE SAME" APPLICANTS: Name : Dr. Babasaheb Ambedkar Marathwada University, Aurangbad Nationality : An Indian University Address - Dr. Babasaheb Ambedkar Marathwada University, Aurangabad. Maharashtra, India. The following specification describes the invention. FIELD OF INVENTION [0001] Embodiments in general relate to a lead-barium-strontium-titanate compound having, a chemical comptosiion expressed by compositional formula Pbi1-xBa0.5xSr0.5xTiO3, [referred to as PBST hereinafter], and more particularly to a ferroelectric tead-barium-strontium-5 titanate compound for use in transducers as sensing element and in capacitors as a dielectric, whereas data storage devices as a memory element, wherein the PBST compound is characterized by having a high dielectric constant, a low dieletric loss, a low porosity, a high mechanical strength and a remnant polarization. The PBST compound of the present invention may bei the form of a pellet or a thin film or any other suitable form, shape and size. A method 10 of fabricating the PBST compound is also disclosed. BACKGROUND OF INVENTION [0002] In the fast growing electronic and computing industry, few basic components like resistors, capacitors, sensors, transducers and memory devices have great significance, wherein the basic working principle of each of these components is well understood. Improvement and 15 enhancement of these components, wherein their reliability, life expectancy and production costs are optimized, is hot field of research. The search for new material that will improve and enhance the performance of these components is sorted after continuously - [0003] Capacitors are electronic components, wherein it is possible to store electrical energy in the form of electric field, for use in devices, for exmple, camera flashes, pulsed lasers, 20 electronic filters etc. The capacitors have found many other uses in the electronics and microelectronics circuits, beyond serving as mere electrical energy store houses. In another form, the microscopic capacitors are used as memory banks of computers, wherein the presence and absence of their electric fields serves as '0' and ' 1' bit of information. [0004] In general, a capacitor comprises a pair of isolated conductor plates (which may 25 be of any shape) separated by a dielectric medium. The dielectric medium may be air, oil, mica, paper, ceramic or any other material like barium titanate, lead magnesium niobate etc., particularly having a dipole moment. When a capacitor is charged, its plates acquire equal but opposite charge, which leads to a potential difference between the plates. The amount of electrical energy that may be stored in a capacitor depends on the geometry of the plates and the dielectric 30 constant of the material between them. The capacity of the capacitor to hold the electrical energy is termed as the capacitance of the capacitor, [0005] An ideal capacitor is desired to have high volumetric efficiency, that is, high capacitance per unit volume, meaning that, the capacitor must be capable of storing large amount of electrical energy, which may be utilized for many appliances like flash in camera, filters used in rectification processes, pulsed lasers etc. [0006] Further, it is desired that the size of the capacitor should be small, which is necessary to build smaller, faster, low electricity consuming and powerful electronic devices for 5 various applications. [OOO7] It is known that high volumetric efficiency of a capacitor may be obtained by use of dielectric material with higher dielectric constant, and at the same time maintaining the capacitor size to certain minimum dimensions. [0008] The electronic devices and hence the components are used in environments where 10 they are subjected to wide range of temperatures. If is desired that the capacitors that are to be used in these electronic devices should provide a stable capacitance over a wide range of temperatures, meaning thereby, the dielectric constant of the dielectric material being used, should exhibit almost stable value over wide irange of temperatures. [0009] Further, in the electronic devices, and hence the components, which are used at 15 high frequencies, it is desired that the capacitor used in the circuitry of those devices should exhibit stable and low dielectric loss at high frequencies. \|00010] In the prior art many compounds are known to be used in capacitor with high dielectric constant and low dielectric loss. [00011 ] In particular, the lead titanate based ceramics are known to exhibit high dielectric 20 constant and low dielectric loss. For example, the paper titled "Dielectric and tunable properties of Pb0.25B3xSr0.75-xTiO3hin films fabricated by a modified sol-gel method" by X. H. Sun et ai, Thin Solid Films 516 (2008) 1308-1312, explains synthesis of Pb0.25BaxSr0.75-xTiO3 hin films by a modified sol-gel method on P1/TiO2/SiO2/Si substrate, wherein the structure, the surface morphology, dielectric and tunable properties of the thin films have been investigated as a 25 function of barium concentration, wherein the investigators found that barium content of these thin films had pronounced effect on above properties of PBST thin fi1ms. [00012] In particular, the paper reports that the grain size, dielectric constant, dielectric loss and tunability increases as the barium content in the thin film increases. [00013] Further, the paper discloses that the Pb0.25Ba0.2Sr0.55TiO3 thin film showed the 30 highest dielectric constant and tunability such as 1390 and 80.6% respectively. [00014] However, the paper does not reveal or even indicate what will be the characteristics of the material with variable amount of all the three, namely, lead, barium and strontium. The paper on contrary discloses a material with fixed percentage of lead, 0.25 and the percentages of barium and strontium are only varied in accordance with the formula Pb0.25BaxSr0.75-xTiO3. [00015] A further important electronic component is the memory element, wherein it is possible to store and/or modify data or information. Memory elements such as dynamic random 5 access memories [DRAMs] and static random access memories [SRAM's] currently dominate the market. But these arc volatile in nature i.e. the stored information is lost when the power fails. [000 16] It is known that the memory elements mentioned above stores information by virtue of a remnant polarization of the material, wherein the material is spontaneously polarized by application of electric field, in analogy to ferromagnetism, the polarization of the material may 10 be removed by application of a reverse field, forming a hysteresis loop. The materials are known as ferroelectric materials in analogy to ferromagnetic materials. [00017] The other available alternatives include complementary metal oxide semiconductors (CMOS) wife battery backup and electrically erasable read only memories (EEPROM's). These non-volatile memories are very expensive. 15 [00038] It is desired to have memory devices which are not volatile in nature that is, the stored information is not lost when the power fails. [00019] It is additionally desired to have memory devices which are economical as compared to that available com merciaily at present. [00020] Pressure transducers [referred to as transducers hereinafter] are components 20 wherein the mechanical stress or pressure is converted into a detectable electrical signal. In prior art, materials known to be used as sensing element in transducers are lead magnesium niobate, lead titanate solid solutions, single crystals of Rochelle salt, piezoelectric composites, etc. [00021] In a transducer with lead titanate (or any other material) based ceramic being used as a pressure sensing element, the pressure induces stress in the sensing element, which in 25 turn leads to generation of electro-motive force {referred to as e.m.f hereinafter] due to the piezoelectric nature of these compounds. This e.m.f. generated is amplified and detected. A suitably calibrated pressure sensing element may be used to build a transducer. [00022] It is desired that the sensing element in the transducer should have high mechanical strength so that it can withstand high pressures, which means that its porosity should 30 be low. [00023] It is desirable that all of these components, namely, capacitors, memory elements and transducers, have reduced size & cost and enhanced capacity & reliability in addition to being low energy consuming devices. [00024] From above, it is evident that in the prior art, the lead titanate based compounds are known to be used in capacitors as dielectric material, as sensing element in transducers and as memory element in memory devices, have one or other disadvantage or shortcomings as discussed above. 5 [00025] It is desired that one could design [a material or] a compound, in particular, a lead titanate based compound, such that the characteristics of the compound including the dielectric constant, the dielectric loss, the porosity, the mechanical strength and remnant polarization may be tailored for a specific application, wherein the characteristics of the compound including the dielectric constant, the dielectric loss, the porosity, the mechanical 10 strength and the remnant polarization may be controlled by changing the percentages of at least one of lead, barium and strontium. [00026] Further, it is desired that the designed lead titanate based compound should be stable over long period of time, meaning thereby, the designed material and hence the devices and/or components fabricated there from should have long lifespan. 15 [00027] Still further, it is desired that the designed lead titanate based compound should be stable over wide range of temperatures, meaning thereby, the designed lead titanate based compound and hence & the devices and/or components fabricated there from, should be able to operate at wide range of temperatures. [00028] Thus, there is a need to have a lead titanate based compound, wherein it is 20 possible to control the dielectric constant, the dielectric loss, the porosity, the mechanical strength and the remnant polarization of the lead titanate based compound by varying the percentages of at least one of lead, barium or strontium, wherein the said lead titanate based compound may be used in devices including capacitors, memory devices and transducers. [00029] Additionally, it is a necessary to have a lead titanate based compound, wherein 25 the compound should have stable behavior over a wide range of temperatures, pressures, higher operating frequency and over a long time span. OBJECT OF INVENTION [00030] An object is to provide a lead titanate based compound. [00031 ] Another object is to provide a lead barium strontium titanate compound. 30 [00032] Still another object is to provide a lead barium strontium titanate compound having chemical composition expressed by compositional formula Pb1-xBa0.5xSr0.5xTiOs wherein x takes values greater than 0.0 and less than 1.0. [00033] Still another object is to provide a method of manufacturing the lead barium strontium titanate compound having chemical composition exspressed by compositional formula Pbi1-xBao 5xSr05HTiO3 wherein x takes values greater than 0.0 and less than 1 .0. [00034] Yet another object is to provide a lead barium strontium titanate compound, 5 wherein the characteristics including the dielectric constant, the dielectric loss, the porosity, the mechanical strength and the remnant polarization may be tailored for a particular application by changing the percentages of at least one of lead, barium and strontium. [00035] Yet another object is to provide a lead barium strontium titanate compound with high dielectric constant even in the form of thin films or pellets or bulk material or any other 10 suitable form, shape and size. [00036] Yet another object is to provide a lead barium strontium titanate compound with low dielectric loss at high frequencies. [00037] Yet another object is to provide a lead barium strontium titanate compound with low porosity. 15 [00038] Still another object is to provide a lead barium strontium titanate compound with high mechanical strength. {00039] Still another object is to provide a lead barium strontium titanate compound with capability to store information and /or data. [00040] Still another object is to provide a lead barium strontium titanate compound 20 which may be used as a dielectric material in capacitors, characterized by the high dielectric constant. [00041] Still another object is to provide a lead barium strontium titanate compound to be used in memory devices as a memory dement characterized by having a remnant polarization. [00042] Still another object is to provide a lead barium strontium titanate compound, 25 used in memory devices as a memory element, which is economical. [00043] Still another object is to provide a lead barium strontium titanate compound which may be used in transducers, wherein the compound is used as a pressure sensing element, and is characterized by its high mechanical strength. [00044] Still another object is to provide a compound which may be used in components 30 such as capacitors, and memory devices such that these components have reduced size & cost and enhanced capacity & reliability in addition to being low energy consuming. [00045] Still another object is to provide a compound which has stable behavior over a wide range of temperatures, pressures and over a long time span. [00046\| The other objects and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings which are incorporated for illustration of preferred embodiments of the present invention and are not intended to limit the scope thereof. 5 STATEMENT OF INVENTION [00047} Accordingly the invention provides a lead titanate based compound, particularly a Lead-Barium-Strontium-Titanate compound. In particular the present invention provides a lead barium strontium compound having a chemical composition expressed by compositional formula, Pb1-xBa0.5xSr0.5xTiO3, where x takes values greater than 0.0 and less than 1.0 Still more 10 particularly, the present invention provides a ferroelectric Lead-Bariurn-Strontium-Titanate compound for use in transducers as sensing element and in capacitors as a dielectric, whereas in data storage devices as a memory element, wherein the PBST compound is characterized by having a high dielectric constant, low dielectric loss, low porosity, high mechanical strength and remnant polarization. The PBST may be in the form of a pellet, bulk material, a thin film or any 15 other suitable form, shape and size. [00048] in accordance with one embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium strontium titanate compound have the chemical composition expressed by compositional formula, Pb1-xBao 5xSr0 5xTi0 , where x takes values greater than 0.0 and less than 1.0 In accordance with 20 the present invention the method of fabricating the lead barium strontium titanate compound comprises the steps of: a. providing starting materials including a lead containing compound, a barium containing compound, a strontium containing compound and a titanium containing compound in predetermined stoichiometric ratio to form a mixture thereof; 25 b. grinding the said mixture for a first predetermined time period t1 to reduce the intermolecular distance, resulting in the formation of first grinded mixture; c. heating said first grinded mixture at a first predetermined temperature T1 for a predetermined time period t'1 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing 30 compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture; d. grinding said first heated mixture for a second predetermined time t2 to facilitate the solid state reaction, resulting in formation of second grinded mixture; e. heating second grinded mixture at a second predetermined temperature T2 for a second predetermined time f2 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are fragmented at molecular level into lead and its other part, barium and 5 its other part, strontium and its other part and titanium and it other part, and thus forming a more homogenized compound by solid state reaction, resulting in formation of second heated mixture; f. grinding said second heated mixture for a third predetermined time t3, again to facilitate the solid state reaction, forming third grinded mixture; 10 g. mixing a suitable binder to said third grinded mixture; h. forming pellets or blocks or any other form of suitable shape and dimensions and weight by application of a predetermined pressure using a mold; i. heating said pellets or blocks or any other form, at a third predetermined temperature TPl for third predetermined time period t'Pl that removes binding element, wherein a 15 single phase lead barium strontium titanate compound formation is completed and the pellets or blocks or any other form of the compound may be used in capacitors,. memory elements or transducers. [00049] In accordance with another embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium 20 strontium titanate compound has the chemical composition expressed by compositional formula, Pb1-xBao.5xSro0.5XTiO3, where x takes values greater than 0.0 and less than 1.0. The method of fabricating the lead barium strontium titanate compound in accordance with this embodiment of the present invention comprises the steps of: a. providing starting materials including a lead containing compound, a barium containing 25 compound, a strontium -containing compound and a titanium containing compound in predetermined stoichiometric ratio to form a mixture thereof; b. grinding said mixture for a first predetermined time period tr to reduce the mtermolecular distance, resulting in the formation of first grinded mixture; c. heating said first grinded mixture at a first predetermined temperature T1 for a 30 predetermined time period t'1 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture; d. grinding said first heated mixture for a second predetermined time t2to facilitate the solid state reaction, resulting in formation of second grinded mixture; e. heating second grinded mixture at a second predetermined temperature T2 for a second predetermined time t'2 wherein said lead containing compound, barium containing 5 compound, strontium containing compound and titanium containing compound are fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, and thus forming a more homogenized compound by solid state reaction, resulting in formation of second heated mixture; 10 f. grinding said second heated mixture for a third predetermined time t3, again to facilitate the solid state reaction, forming third grinded mixture; g. heating third grinded mixture at a third predetermined temperature T3 for a third predetermined time t'3 wherein the second heated mixture gets more homogenized, resulting in formation of third heated mixture; 15 h. grinding said third heated mixture for a fourth predetermined time t4, again to facilitate the solid state reaction, forming fourth grinded mixture; i. mixing a suitable binder to said fourth grinded mixture; j. forming pellets or blocks or any other form of suitable shape and dimensions and weight by application of a predetermined pressure using a moid; 20 k. heating said pellets or blocks or any other form, at a fourth predetermined temperature Tp2 for fourth predetermined time period t'p2that removes binding element, wherein the a single phase lead barium strontium titanate compound formation is completed and the pellets or blocks or any other form of the compound may be used in capacitors, memory elements or transducers. 25 [00050] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the 30 embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications. BRIEF DESCRIPTION OF FIGURES This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which: [00051] FIGURE 1 is a flow chart illustrating the method of fabricating the inventive 5 lead barium strontium titanate compound in accordance with one embodiment of the present invention; [00052] FIGURE 2 is a flow chart illustrating the method of fabricating the inventive lead barium strontium titanate compound in accordance with another embodiment of the present invention; 10 [00053] FIGURE 3 illustrates graphs of variation of dielectric constant (e) of the inventive lead barium strontium titanate compound at various temperatures as a function of frequency for x = 0.0 to x = 1.0 with the interval of 0.2. [00054] FIGURE 4 illustrates graphs of variation of dielectric constant (E) of the inventive lead barium strontium titanate compound at various frequencies as a function of 15 temperature for x = 0.0 to x — 1.0 with the interval of 0.2. l00055J FIGURE 5 illustrates graphs of variation of dielectric Joss (tan δ) of the inventive lead barium strontium titanate compound at various temperatures as a function frequency for x = 0.0 to x = 1.0 with the interval of 0.2. [00056] FIGURE 6 illustrates a graph of variation of the porosity of the inventive lead 20 barium strontium titanate compound as a function of x value, wherein x takes values from 0.0 to 1.0; [00057] FIGURE 7 illustrates a graph of variation, of the transition temperature of the inventive lead barium strontium titanate compound as a function of x value, wherein x takes values from 0.0 to 1.0. 25 DETAILED DESCRIPTION OF INVENTION [00058] The embodiments herein, the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the 30 embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein. [00059] The inventors have conducted extensive investigations with the above mentioned objects in an approach to discover a lead titanate compound with simultaneous substitution of barium and strontium, wherein the said lead titanate compound exhibits an improved dielectric behavior along with reduced dielectric loss, reduced porosity, enhanced mechanical strength and 5 a remnant polarization. [00060] The embodiments herein achieve a ferroelectric lead barium strontium titanate compound having the chemical composition expressed by the compositional formula Pb1- xBao 5XSr0.5xTiO3,where x takes values greater than 0.0 and less than 1.0, wherein the lead barium strontium titanate compound exhibits a high dielectric constant, a low dielectric loss, a low 10 porosity, high mechanical strength and remnant polarization. [00061] In accordance with the present invention, the inventors have observed that substitution of barium influences dielectric properties of the compound. The inventors have observed a pronounced effect of barium substitution on the dielectric properties [00062] In accordance with the present invention, it is observed that the substitution of 15 strontium reduces the porosity and shifts the transition temperature towards ambient temperature, particularly when the percentage of strontium was 30%, minimum value of porosity was observed with lead contained ceramic, that is, when the value of x was 0.6. [00063] In accordance with one embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium 20 strontium titanate compound have the chemical composition expressed by the compositional formula, Pb1-xBao.5xSro.5xTiO3, where x takes values greater than 0.0 and less than 1.0. Referring to FIGURE I, wherein the method of is depicted in form of flow chart 101, the method of fabricating the lead barium strontium tttanate compound in accordance with the present invention comprises the steps of: 25 a. starting materials including a lead containing compound, a barium containing compound, a strontium containing compound and a titanium containing compound in predetermined stoichiometric ratio to form a mixture thereof 102; b. grinding the said mixture for a first predetermined time period t1 to reduce the intermolecular distance, resulting in the formation of first grinded mixture 103; 30 c. heating said first grinded mixture at a first predetermined temperature T1 for a predetermined time period t'1 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture 104; d. grinding said first heated mixture for a second predetermined time t2 to facilitate the solid state reaction, resulting in formation of second grinded mixture 105; 5 e. heating second grinded mixture at a second predetermined temperature T2 for a second predetermined time t2 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium, and it other part, and thus forming a more 10 homogenized compound by solid state reaction, resulting in formation of second heated mixture 106; f. grinding said second heated mixture for a third predetermined time t3, again to facilitate the solid state reaction, forming third grinded mixture 107; g. mixing a suitable binder to said third grinded mixture 108; 15 h. forming pellets or blocks or any other form of suitable shape and dimensions and weight by application of a predetermined pressure using a mold 109; i. heating said pellets or blocks or any other form, at a third predetermined temperature Tp1 for third predetermined time period t'P1 that removes binding element, wherein a single phase lead barium strontium titanate compound formation is completed 110 and the 20 pellets or blocks or any other form of the compound may be used in capacitors, memory elements or transducers. [00064] In accordance with one embodiment of the present invention, the lead containing compound is lead oxide. (00065] In accordance with one embodiment of the present invention, the barium 25 containing compound is barium carbonate. [00066] In accordance with one embodiment of the present invention, the strontium containing compound is strontium carbonate. [00067] In accordance with one embodiment of the present invention, the titanium containing compound is titanium oxide. 30 [00068] In accordance with one embodiment of the present invention, the grinding of mixtures including the mixture, the first heated mixture and the second heated mixture is carried out using an "agate mortar". [00069] In accordance with one embodiment of the present invention, the predetermined grinding time t1 is from about 60 minutes to 180 minutes. [00070] In accordance with one preferred embodiment of the present invention, the predetermined grinding time t1 is 120 minutes. [00071] In accordance with one embodiment of the present invention, the first grinded mixture is heated to a temperature T1 wherein T1 ranges from about 723 K to about 1023 K; most 5 preferably T1 is 873 ± 10 K. [00072] In accordance with one embodiment of the present invention, the first time period for heating the first grinded mixture t'1, wherein t1 ranges from about 360 minutes to about 600 minutes, most preferably t'1 is 480 ±15 minutes. [00073] In accordance with one embodiment of the present invention, the predetermined 10 grinding time t2 is from about 60 minutes to about 180 minutes, and most preferably t2 is 120 minutes. [00074] In accordance with one embodiment of the present invention, the second grinded mixture is heated to a temperature T2, wherein T2 canges from 923 K to about 1223 K; most preferably T2 is 1073 ± 10 K. 15 [00075] In accordance with one embodiment of the present invention, the second time period for heating the first grinded mixture t2 ranges from about 240 minutes to about 480 minutes, most preferably t'2 is 360 ± 15 minutes. [00076] In accordance with one embodiment of the present invention, the grinding time for second heated mixture t3 ranges from about 60 minutes to about 180 minutes, and most 20 preferably t3 is .120 minutes. [00077] In accordance with one embodiment of the present invention, the pressure applied during molding of pellets ranges from 0.1 tons to 10 tons, preferably from 3 to 8 tons, most preferably the pressure is 6 ton. [00078] In accordance with one embodiment of the present invention, the binder used for 25 binding the third grinded mixture is polyvinyl alcohol. [00079] In accordance with one embodiment of the present invention, the pellets or blocks are heated to the temperature TPl ranging from about 873 K to about 1423 K and most preferably Tp1, is 1273 ± 10 K. [00080] In accordance with one embodiment of the present invention, the pellets or 30 blocks are heated to the third temperature TP1 for a predetermined time t'P1. wherein t'P1 ranges from about 300 minutes to about 420 minutes and most preferably t' Pl is 360 minutes. [00081] In accordance with one embodiment, the pellets have a diameter ranging from 8 mm to about 10 and thickness ranging from about 1 mm to about 3 mm. [00082] In accordance with another embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium strontium titanate compound have the chemical composition expressed by compositional formula, Pb\|.xBao 5)CSr0 5ltTi03, where x takes values greater than 0.0 and less than 1.0 Referring to FIGURE 5 2, which depicts a flow chart 20 i for the method for fabrication of the PBST compound in accordance with another embodiment of the present invention, the method of fabricating the lead barium strontium titanate compound in accordance with another embodiment of the present invention comprises the steps of: a. providing starting materials including a lead containing compound, a barium containing 10 compound, a strontium containing compound and a titanium containing compound in predetermined stoichiometric ratio to form a mixture thereof 202; b. grinding said mixture for a iirst predetermined time period tT to reduce the intermolecular distance, resulting in the formation of first grinded mixture 203; c. heating said first grinded mixture at a first predetermined temperature T] for a 15 predetermined time period t'i wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture 204; 20 d. grinding said first heated mixture for a second predetermined time %2 to facilitate the solid state reaction, resulting in formation of second grinded mixture 205; e. heating second grinded mixture at a second predetermined temperature T2 for a second predetermined time t'2 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are 25 fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, and thus forming a more homogenized compound by solid state reaction, resulting in formation of second heated mixture 206; f grinding said second heated mixture for a third predetermined time t?, again to facilitate 30 the solid state reaction, forming third grinded mixture 207; g. heating third grinded mixture at a third predetermined temperature T3 for a third predetermined time t'j wherein the second heated mixture gets more homogenized, resulting in formation of third heated mixture 208; h. grinding said third heated mixture for a fourth predetermined time t1, again to facilitate the solid state reaction, forming fourth grinded mixture 209; i. mixing a suitable binder to said fourth grinded mixture 210; j. forming pellets or blocks or any other form of suitable shape and dimensions and weight 5 by application of a predetermined pressure using a mold 211; k. heating said pellets or blocks or any other form, at a fourth predetermined temperature Tp2 for fourth predetermined time period t'?2 that removes binding element, wherein the single phase lead barium strontium titanate compound formation is completed 212 and the pellets or blocks or any other form of the compound may be used in capacitors, 10 memory elements or transducers. [00083] In accordance with one embodiment of the present invention, the time period t1 for grinding said mixture ranges from about 60 minutes to about 180 minutes and most preferably t1 is about 120 minutes. [00084] In accordance with one embodiment of the present invention, the first grinded 15 mixture is heated to first predetermined temperature T1 ranging from about 723 K to about 1023 K and most preferably T1 is 873 ± 10 K. [00085] In accordance with one embodiment of the present invention, the first grinded mixture is heated to first predetermined temperature T1 for a predetermined time period t'1, wherein t'1 ranges from about 360 minutes to about 600 minutes, most preferably t'1 is 480 ±15 20 minutes. [00086] In accordance with one embodiment of the present invention, the predetermined grinding time -t2 is from about 60 minutes to about 180 minutes, and most preferably t2 is 120 minutes. [00087] In accordance with one embodiment of the present invention, the second grinded 25 mixture is heated to a temperature T2; wherein T2 ranges from 923 K to about 1223 K, most preferably T2 is 1073 ± 10 K [00088] In accordance with one embodiment of the present invention, the second time period for heating the first grinded mixture t'2 ranges from about 240 minutes to about 480 minutes, most preferably t2 is 360 ± 15 minutes. 30 [00089] In accordance with one embodiment of the present invention, the said second heated mixture is grinded for a third predetermined time t3, wherein t3 ranges from about 60 to about 180 minutes; most preferably t3 is 120 minutes. [00090] In accordance with one embodiment of the present invention, the said third grinded mixture is heated to a third predetermined temperature T3, wherein T3 ranges from about 1023 K to about 1423 K, and most preferably T3 is 1273 ± 10 K. [00091] In accordance with one embodiment of the present invention, the third grinded 5 mixture is heated to a third predetermined temperature T3 for a third predetermined time t'3, wherein t'3 ranges from about 240 to about 480 minutes and most preferably t'3 is about 360 ± 15 minutes. [00092] In accordance with one embodiment of the present invention, the said third mixture is grinded for a fourth predetermined time t4, wherein t4 ranges from about 60 minutes to 10 about 180 minutes and most preferably 120 minutes. [00093] In accordance with one embodiment of the present invention, the said binder mixed said third grinded mixture is polyvinyl alcohol. [00094] In accordance with one embodiment of the present invention, the pellets have a thickness ranging from about I mm to about 3 mm and diameter ranging from about 8 to about 10 15 mm. [00095] In accordance with one embodiment of the present invention, the pellets have weight ranging from about gm to about 5 gm. [00096] In accordance with one embodiment of the present invention, the pellets are formed by application of pressure, wherein the pressure applied ranges from about 0.1 ton to 20 about 10 ton, preferably from about 3 to about 8 tons and most preferably the pressure is 6 ton. [00097] In accordance with one embodiment of the present invention, the pellets are heated to a predetermined temperature Tp2, wherein Tp2 ranges from about 1273 K to 1673 K; and most preferably Tp2 is 1473 K; [00098] In accordance with one embodiment of die present invention, the pellets are 25 heated to a fourth predetermined temperature Tp for a fourth predetermined time period t'p, wherein t'p ranges from about 120 to about 360 minutes and most preferably 240 minutes. [00099] In one preferred embodiment the lead containing compound is lead oxide (PbO) with very high purity, preferably greater than 99.9 %. [000100] In one preferred embodiment the barium containing compound is barium 30 carbonate (BaCO3) having very high purity, preferably greater than 99.9 %. [000101] In one preferred embodiment the strontium containing compound is strontium carbonate (S1CO3) having purity greater than 99.9 %. [000102] In one preferred embodiment the titanium containing compound is titanium oxide (Ti02) with purity greater than 99.9 %. [000103] In accordance with one embodiment of the present invention, the invetnive lead barium strontium ptanate compound having the chemical composition expressed by compositional formula Pb1-xBao.5xSro.5XTiO3, exhibits a surprisingly high dielectric constant ranging from about l84 to about 3022, particularly, when x takes values between greater than 0.0 5 and less than 1.0, wherein the dielectric constant was measured using commercially available instrument from HP with model number HP 4284A LCR Q meter. Typical minimum and maximum values of the dielectric constant at particular temperature & frequency as a function of x values are tabulated in table 1 below. The graphs of variation of dielectric constant of the inventive PBST compound with change in value of x as a function of frequency at various 10 temperatures are illustrated in FIGURE 3 and FIGURE 4. [000104] The dielectric constant is observed to decrease with increasing frequency. It attains almost stable value at higher frequencies. [000105] The dielectric constant is observed to increase initially with rise in temperature up to the transition temperature, Tc. With further rise in temperature, the dielectric constant shows 15 a decreasing trend. TABLE 1 SAMPLE X COMPOUND DIELECTRIC CONSTANT (□) εmax FREQ TEMP (K) εmax FREQ (Hz) TEMP (K) I 0.0 PbTiO3 393 106 623 9222 100 763 II 0.2 Pb0.8Ba0.1Sr0.1TiO3 245 10s 623 3022 100 708 III 0.4 Pb0.6Ba0.2Sr0.1TiO3 187 106 723 1641 100 583 IV 0.6 Pb0.6Ba0.3Sr0.3TiO3 201 106 373 510 100 518 V 0.8 Pb0.2Ba0.4Sr0.4TiO3 184 106 303 414 100 423 VI 1.0 Ba0.5Sr0.5TiO3 163 106 448 364 100 303 [000106] The inventors found that the high dielectric constant of the lead barium strontium titanate compound having the chemical composition expressed by compositional 20 formula Pb1-xBao.5xSro.5xTi03, wherein x takes values greater than 0.0 and 1.0 may be attributed to the fact that ferroelectric crystals possess regions with uniform polarization called ferroelectric domains. Within a domain, all the electric dipolcs arc aligned in the same direction. There may be many domains in a crystal separated 6y interfaces called domain walls. A ferroelectric single crystal, when grown, has multiple ferroelectric domains. The dielectric constant of the material 25 increases by domain wall motion. [000107] The dielectric constant of the lead barium strontium titanate compound having the chemical composition expressed by compositional formula Pb1-xBao.5xSr0.5XTiO3, wherein x takes values greater than 0.0 and less than 1.0 was measured in pellet formed by using hydraulic press at room temperature. [000108] In one embodiment of the present invention, the inventive lead barium strontium titanate compound having the chemical composition expressed by compositional 5 formula Pb1-xBao.5xSro.5xTiO3, exhibits low dielectric loss, particularly, when x takes values between 0.0 and 1.0, wherein the dielectric loss was measured using commercially available instrument from HP with model number HP 4284A LCR Q meter. Typical minimum and maximum values of the dielectric loss at particular temperature & frequency as a function of x values are tabulated in table 2 below. The graphs of variation of dielectric loss of the inventive PBST compound with change in value of x as a function of frequency at various temperatures are illustrated in FIGURE 5. The dielectric loss shows a declining trend with rise in frequency. TABLE 2 SAMPLE X COMPOUND DIELECTRIC LOSS (tan 6) tan 5 (mils) FREQ (Hz) TEMP (K) tan 8 (max) FREQ (Hz) TEMP (K) I 0.0 PbTiO3, 0.13- 106 623 3.26 2000 723 II 0.2 Pbo.8Bao.1Sr0.3TiO3 0.137 106 623 2.33 5000 723 III 0.4 Pbo.6Bao.2Sro.3TiO3 0.128 1O6 623 2.09 1000 673 IV 0.6 Pb0.4Bao.3Sro.3TiO3 0,036 106 623 0.683 1000 723 V 0.8 Pb0.4Ba0.4Sr0.4TiO3 0.0022 106 623 0.748 1000 723 VI 1.0 Ba0.5Sr0.5TiO3 0.02 106 623 0.296 1000 723 [000109] The reduced dielectric loss observed for the inventive lead barium strontium 5 titanate compound having the chemical composition expressed by composition formula Pb1-x- Bao.5xSr0.5xTi03, is attributed to porosity of the material. Lower porosity results in smaller grain size which in turn reduces the dielectric loss as relative density and porosity are two important factors that control the dielectric loss. Also, reduction in domain wall contribution contributes to the reduction in the loss. 20 [000110] In one embodiment of the present invention, the inventive lead barium strontium titanate compound having the chemical composition expressed by compositional formula Pb1-xBao.5xSro.5xTiO3, exhibits low porosity and high mechanical strength, particularly, when x takes values between 0.6 and 0.8. It is well known that a material with low porosity, in general, has a high mechanical strength. The variation of porosity as a function of x is depicted in 25 FIGURE 6. [000111 ] The percentage porosity was calculated using the formula % porosity = [1 - (pxy/pth)] x 100, where pexp is the experimental density of the PBST compound under consideration, calculated using water immersion method and pth, is the theoretical density of the PBST compound obtained from X-ray diffractometery analysis of the compound. These calculations are well-known in the art and a reference to the same may be found in the book titled "Elements Of X-ray Diffraction'1 5 by B. D. Cullity, from Addison-Wesley Publishing Company, inC [000112] Typical values of porosity of the inventive PBST compound are tabulated in table 3 below and are depicted in FIGURE 6, which indicate that the porosity of the inventive PBST compound decrease with increasing dopant concentration. TABLE 3 SAMPLE I COMPOWTO POROSITY (%) I 0.0 PbTi3 12 II t).2 Pbo..8Bao..1Sr0..1Ti03 11 III 0.4 Pbo.6Ba0.2Sr0.2TiO3 9 IV 0.6 Pbo.4Bao.3Sro..3TiO3 S V 0.8 Pb0.2Ba0.4Sro.4TiO3, 8 VI 1.0 Bao.5Sro.5Ti03 7 J X» [000113] The reduction in porosity can be attributed tp the doping of smaller Sr2+ ion at the Pb site. [000114] In accordance with one embodiment of the foresent invention, the inventive lead barium strontium titanate compound is observed to exhibit piezoelectric nature that is, the material has ability to develop an electrical charge proportional to a mechanical stress. 15 \|000115] In accordance with one embodiment of the present invention, the inventive lead barium strontium titanate compound is observed to exhibit paraelectric nature above the Curie temperature, wherein the Curie temperature depends upon the composition. Above the transition temperature, ferroelectric materials become paraelentries. (000116] The transition temperatures refer to the temperature corresponding to the 20 dielectric maxima, in the plot depicting variation of dielectric constant with temperature, given by FIGURE 6. [000117] Typical transition temperatures for the inventive PBST compound of the present invention, are tabulated in table 4 below, the same is depicted in graphical form in FIGURE 7. 25 TABLE 4 SAMPLE X COMPOUND TRANSITION TEMPERATURE (Kelvin) I 0.0 PbTiO, 763 n 0.2 Pb0.8Ba0.1Sr0.8TiO3 435 II 0-4 Pb0.6Ba0.2Sr0.2TiO3 583 IV 0.6 Pb0.4Ba0.3Sr0.3TiO3 518 V 0.8 Pb0.2Ba0.4Sr0.4TiO3 423 vi 1.0 Ba0.5Sr0.5TiO3 BELOW ROOM TEMPERATURE [000118] In accordance with one embodiment of the present invention, the inventive lead barium strontium titanate compound is observed to have perovskite structure, which has been Confirmed by X-ray diffractometry. [0001 \9\ In accordance with one embodiment of the present invention, the inventive lead 5 barium strontium titanate compound having a high dielectric constant may used in a capacitor comprising at least a pair of conductor plates and a dielectric material film or slab between the pair of said conductor plates, the dielectric material film or slab being constructed from a lead barium strontium titanate compound with chemical composition Pbi.xBao.5xSrosxTi03, wherein x takes values greater than 0.0 and less than 1.0. 10 J000120} In accordance with one embodiment of the present invention, the inventive lead barium strontium titanate compound exhibits a dielectric constant m die range from about 184 to about 3022. \|000121) In accordance wuh one embodiment of the present invention, the inventive lead barium strontium titanate compound exhibits a dielectric loss less than about 0.19 at frequencies 15 greater than about 10 kHz. [000122] In accordance with one embodiment of the present invention, a capacitor comprising at least a pair of conductor plates and a dielectric material film or slab between the pair of said conductor plates is disclosed, wherein the dielectric material film or slab being constructed from a lead barium strontium titanate compound with chemical composition Pbi- 20 xBao ^xSros^TiO^ wherein x takes values greater than 0.0 and Jess than J.0, wherein the dielectric material film or slab has a dielectric constant in the range from 184 to 3022. [000123] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from 25 the generic concept, and, tiierefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, whde the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments 30 herein can be practiced with modification within the spirit and scope of the embodiments as described herein. We Claim- 1. A lead barium strontium titanate compound having a chemical composition expressed by compositional formula Pb1-xBao.5xSro.5xTi03 wherein x takes values greater than 0.0 and less than 1.0, and exhibiting a dielectric constant, a dielectric loss, a porosity, a remnant 5 polarization and a transition temperature. 2. The lead barium strontium titanate compound of claim 1, wherein said compound exhibits the said dielectric constant in the range from about 184 to about 3022, the said dielectric loss of less than about 0.19 at frequencies greater than 10 kHz, the said porosity in the range from about 7 % to about 12 % and the said transition temperature ranging 10 from about below room temperature to about 763 K. 3. A method of fabricating the lead barium strontium titanate compound comprising the steps of: a. providing starting materials including a lead containing compound, a barium containing compound, a strontium containing compound and a titanium containing compound in 15 predetermined stoichiometric ratio to form a mixture thereof; b. grinding the said mixture for a first predetermined time period t1 to reduce the intermolecular distance, resulting in the formation of first grinded mixture; c. heating said first grinded mixture at a first predetermined temperature T1 for a predetermined time period t'1 wherein said lead containing compound, barium containing 20 compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture; d. grinding said first heated mixture for a second predetermined time t2to facilitate the solid 25 state reaction, resulting in formation of second grinded mixture; e. heating second grinded mixture at a second predetermined temperature T2 for a second predetermined time t'2 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are fragmented at molecular level into lead and its other part, barium and its other part, 30 strontium and its other part and titanium and it other part, and thus forming a more homogenized compound by solid state reaction, resulting in formation of second heated mixture; f. grinding said second heated mixture for a third predetermined time t3, again to facilitate the solid state reaction, forming third grinded mixture; £5 1 \i g. mixing a suitable binder to said third grinded mixture; h. forming pellets or blocks or any other form of suitable shape and dimensions and weight by application of a predetermined pressure using a mold; i. heating said pellets or blocks or any other form, at a predetermined temperature TP1 for 5 predetermined time period t'Pl that removes binding element and forms a single phase compound, thereby forming heated pellets or blocks or thin films. 4. The method of claim 3, wherein after performing step (f) additional steps of; i. heating said third grinded mixture to a third predetermined temperature T3 and for third predetermined time t'3 resulting in formation of third heated mixture; 10 and ii. grinding said third heated mixture for a predetermined time μ resulting in formation of fourth grinded mixture followed by; g. mixing a suitable binder to said fourth grinded mixture; h. forming pellets or thin films or blocks of suitable dimensions and weight by application 15 of a predetermined pressure using a mold; i. heating said pellets or thin films or blocks at a predetermined temperature Tp for third predetermined time period t'p that removes binding element and forms a single phase compound, thereby forming pellets or blocks or thin films. 5. The method of claim 3, wherein said predetermined grinding time t1 is from about 60 20 minutes to 180 minutes, said first grinded mixture is heated to a temperature T1 wherein T1 ranges from about 723 K to about 1023 K, and said predetermined first time period for heating the first grinded mixture t1 ranges from about 360 minutes to about 600 minutes. 6. The method of claim 3, wherein said predetermined second grinding time t2 is from about 60 minutes to about 180 minutes, said second grinded mixture is heated to a temperature 25 T2, wherein T2 ranges from 923 K to about 1223 K and said second predetermined time period for heating the first grinded mixture t'2 ranges from about 250 minutes to about 500 minutes. 7. The method of claim 3, wherein, said third predetermined grinding time for second heated mixture t3 ranges from about 60 minutes to about 180 minutes. 30 8. The method of claim 3, wherein said pressure applied during formation of pellets ranges from 0.1 tons to 10 tons. 9. The method of claim 3, wherein said pellets or blocks are heated to the temperature Tp ranging from about 873 K to about 1423 K and said pellets or blocks arc heated to the 25 temperature TPl for a predetermmed time t'p, wherein t'p ranges from about 120 minutes to about 360 minutes. 10, The method of claim 4, wherein said third grinded mixture is heated to a temperature T3 ranging from about 1023 K to about 1423 K, for a time f 3 ranging from about 240 to 480 minutes, said third heated mixture is grinded for a fourth predetermined time t4 forming fourth grinded mixture and said pellets or blocks are heated to the temperature Tp ranging from about 1273 K to about 1673 K for a predetermined time t'p, wherein t'p ranges from about 120 minutes to about 360 minutes.

Full Text

FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005
COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13)
TITLE OF THE INVENTION
"A LEAD-BARTUM-STRONTIUM-TITANATE COMPOUND [Pb1-XBa0.5XSr0.5XTio3] AND A METHOD OF FABRICATING THE SAME"
APPLICANTS:
Name : Dr. Babasaheb Ambedkar Marathwada University,
Aurangbad
Nationality : An Indian University
Address - Dr. Babasaheb Ambedkar Marathwada University,
Aurangabad. Maharashtra, India.
The following specification describes the invention.

FIELD OF INVENTION
[0001] Embodiments in general relate to a lead-barium-strontium-titanate compound having, a chemical comptosiion expressed by compositional formula Pbi1-xBa0.5xSr0.5xTiO3, [referred to as PBST hereinafter], and more particularly to a ferroelectric tead-barium-strontium-5 titanate compound for use in transducers as sensing element and in capacitors as a dielectric, whereas data storage devices as a memory element, wherein the PBST compound is characterized by having a high dielectric constant, a low dieletric loss, a low porosity, a high mechanical strength and a remnant polarization. The PBST compound of the present invention may bei the form of a pellet or a thin film or any other suitable form, shape and size. A method 10 of fabricating the PBST compound is also disclosed.
BACKGROUND OF INVENTION [0002] In the fast growing electronic and computing industry, few basic components like resistors, capacitors, sensors, transducers and memory devices have great significance, wherein the basic working principle of each of these components is well understood. Improvement and 15 enhancement of these components, wherein their reliability, life expectancy and production costs are optimized, is hot field of research. The search for new material that will improve and enhance the performance of these components is sorted after continuously -
[0003] Capacitors are electronic components, wherein it is possible to store electrical energy in the form of electric field, for use in devices, for exmple, camera flashes, pulsed lasers, 20 electronic filters etc. The capacitors have found many other uses in the electronics and microelectronics circuits, beyond serving as mere electrical energy store houses. In another form, the microscopic capacitors are used as memory banks of computers, wherein the presence and absence of their electric fields serves as '0' and ' 1' bit of information.
[0004] In general, a capacitor comprises a pair of isolated conductor plates (which may 25 be of any shape) separated by a dielectric medium. The dielectric medium may be air, oil, mica, paper, ceramic or any other material like barium titanate, lead magnesium niobate etc., particularly having a dipole moment. When a capacitor is charged, its plates acquire equal but opposite charge, which leads to a potential difference between the plates. The amount of electrical energy that may be stored in a capacitor depends on the geometry of the plates and the dielectric 30 constant of the material between them. The capacity of the capacitor to hold the electrical energy is termed as the capacitance of the capacitor,
[0005] An ideal capacitor is desired to have high volumetric efficiency, that is, high capacitance per unit volume, meaning that, the capacitor must be capable of storing large amount

of electrical energy, which may be utilized for many appliances like flash in camera, filters used in rectification processes, pulsed lasers etc.
[0006] Further, it is desired that the size of the capacitor should be small, which is necessary to build smaller, faster, low electricity consuming and powerful electronic devices for 5 various applications.
[OOO7] It is known that high volumetric efficiency of a capacitor may be obtained by use of dielectric material with higher dielectric constant, and at the same time maintaining the capacitor size to certain minimum dimensions.
[0008] The electronic devices and hence the components are used in environments where
10 they are subjected to wide range of temperatures. If is desired that the capacitors that are to be
used in these electronic devices should provide a stable capacitance over a wide range of
temperatures, meaning thereby, the dielectric constant of the dielectric material being used,
should exhibit almost stable value over wide irange of temperatures.
[0009] Further, in the electronic devices, and hence the components, which are used at 15 high frequencies, it is desired that the capacitor used in the circuitry of those devices should exhibit stable and low dielectric loss at high frequencies.
|00010] In the prior art many compounds are known to be used in capacitor with high dielectric constant and low dielectric loss.
[00011 ] In particular, the lead titanate based ceramics are known to exhibit high dielectric 20 constant and low dielectric loss. For example, the paper titled "Dielectric and tunable properties of Pb0.25B3xSr0.75-xTiO3hin films fabricated by a modified sol-gel method" by X. H. Sun et ai, Thin Solid Films 516 (2008) 1308-1312, explains synthesis of Pb0.25BaxSr0.75-xTiO3 hin films by a modified sol-gel method on P1/TiO2/SiO2/Si substrate, wherein the structure, the surface morphology, dielectric and tunable properties of the thin films have been investigated as a 25 function of barium concentration, wherein the investigators found that barium content of these thin films had pronounced effect on above properties of PBST thin fi1ms.
[00012] In particular, the paper reports that the grain size, dielectric constant, dielectric loss and tunability increases as the barium content in the thin film increases.
[00013] Further, the paper discloses that the Pb0.25Ba0.2Sr0.55TiO3 thin film showed the 30 highest dielectric constant and tunability such as 1390 and 80.6% respectively.
[00014] However, the paper does not reveal or even indicate what will be the characteristics of the material with variable amount of all the three, namely, lead, barium and strontium. The paper on contrary discloses a material with fixed percentage of lead, 0.25 and the

percentages of barium and strontium are only varied in accordance with the formula Pb0.25BaxSr0.75-xTiO3.
[00015] A further important electronic component is the memory element, wherein it is possible to store and/or modify data or information. Memory elements such as dynamic random 5 access memories [DRAMs] and static random access memories [SRAM's] currently dominate the market. But these arc volatile in nature i.e. the stored information is lost when the power fails.
[000 16] It is known that the memory elements mentioned above stores information by
virtue of a remnant polarization of the material, wherein the material is spontaneously polarized
by application of electric field, in analogy to ferromagnetism, the polarization of the material may
10 be removed by application of a reverse field, forming a hysteresis loop. The materials are known
as ferroelectric materials in analogy to ferromagnetic materials.
[00017] The other available alternatives include complementary metal oxide
semiconductors (CMOS) wife battery backup and electrically erasable read only memories
(EEPROM's). These non-volatile memories are very expensive.
15 [00038] It is desired to have memory devices which are not volatile in nature that is, the
stored information is not lost when the power fails.
[00019] It is additionally desired to have memory devices which are economical as compared to that available com merciaily at present.
[00020] Pressure transducers [referred to as transducers hereinafter] are components 20 wherein the mechanical stress or pressure is converted into a detectable electrical signal. In prior art, materials known to be used as sensing element in transducers are lead magnesium niobate, lead titanate solid solutions, single crystals of Rochelle salt, piezoelectric composites, etc.
[00021] In a transducer with lead titanate (or any other material) based ceramic being
used as a pressure sensing element, the pressure induces stress in the sensing element, which in
25 turn leads to generation of electro-motive force {referred to as e.m.f hereinafter] due to the
piezoelectric nature of these compounds. This e.m.f. generated is amplified and detected. A
suitably calibrated pressure sensing element may be used to build a transducer.
[00022] It is desired that the sensing element in the transducer should have high mechanical strength so that it can withstand high pressures, which means that its porosity should 30 be low.
[00023] It is desirable that all of these components, namely, capacitors, memory elements and transducers, have reduced size & cost and enhanced capacity & reliability in addition to being low energy consuming devices.

[00024] From above, it is evident that in the prior art, the lead titanate based compounds
are known to be used in capacitors as dielectric material, as sensing element in transducers and as
memory element in memory devices, have one or other disadvantage or shortcomings as
discussed above.
5 [00025] It is desired that one could design [a material or] a compound, in particular, a
lead titanate based compound, such that the characteristics of the compound including the dielectric constant, the dielectric loss, the porosity, the mechanical strength and remnant polarization may be tailored for a specific application, wherein the characteristics of the compound including the dielectric constant, the dielectric loss, the porosity, the mechanical 10 strength and the remnant polarization may be controlled by changing the percentages of at least one of lead, barium and strontium.
[00026] Further, it is desired that the designed lead titanate based compound should be
stable over long period of time, meaning thereby, the designed material and hence the devices
and/or components fabricated there from should have long lifespan.
15 [00027] Still further, it is desired that the designed lead titanate based compound should
be stable over wide range of temperatures, meaning thereby, the designed lead titanate based compound and hence & the devices and/or components fabricated there from, should be able to operate at wide range of temperatures.
[00028] Thus, there is a need to have a lead titanate based compound, wherein it is
20 possible to control the dielectric constant, the dielectric loss, the porosity, the mechanical strength
and the remnant polarization of the lead titanate based compound by varying the percentages of at
least one of lead, barium or strontium, wherein the said lead titanate based compound may be
used in devices including capacitors, memory devices and transducers.
[00029] Additionally, it is a necessary to have a lead titanate based compound, wherein 25 the compound should have stable behavior over a wide range of temperatures, pressures, higher operating frequency and over a long time span.
OBJECT OF INVENTION
[00030] An object is to provide a lead titanate based compound.
[00031 ] Another object is to provide a lead barium strontium titanate compound.
30 [00032] Still another object is to provide a lead barium strontium titanate compound
having chemical composition expressed by compositional formula Pb1-xBa0.5xSr0.5xTiOs wherein x takes values greater than 0.0 and less than 1.0.

[00033] Still another object is to provide a method of manufacturing the lead barium strontium titanate compound having chemical composition exspressed by compositional formula Pbi1-xBao 5xSr05HTiO3 wherein x takes values greater than 0.0 and less than 1 .0.
[00034] Yet another object is to provide a lead barium strontium titanate compound, 5 wherein the characteristics including the dielectric constant, the dielectric loss, the porosity, the mechanical strength and the remnant polarization may be tailored for a particular application by changing the percentages of at least one of lead, barium and strontium.
[00035] Yet another object is to provide a lead barium strontium titanate compound with high dielectric constant even in the form of thin films or pellets or bulk material or any other 10 suitable form, shape and size.
[00036] Yet another object is to provide a lead barium strontium titanate compound with low dielectric loss at high frequencies.
[00037] Yet another object is to provide a lead barium strontium titanate compound with
low porosity.
15 [00038] Still another object is to provide a lead barium strontium titanate compound with
high mechanical strength.
{00039] Still another object is to provide a lead barium strontium titanate compound with capability to store information and /or data.
[00040] Still another object is to provide a lead barium strontium titanate compound 20 which may be used as a dielectric material in capacitors, characterized by the high dielectric constant.
[00041] Still another object is to provide a lead barium strontium titanate compound to be used in memory devices as a memory dement characterized by having a remnant polarization.
[00042] Still another object is to provide a lead barium strontium titanate compound, 25 used in memory devices as a memory element, which is economical.
[00043] Still another object is to provide a lead barium strontium titanate compound which may be used in transducers, wherein the compound is used as a pressure sensing element, and is characterized by its high mechanical strength.
[00044] Still another object is to provide a compound which may be used in components 30 such as capacitors, and memory devices such that these components have reduced size & cost and enhanced capacity & reliability in addition to being low energy consuming.
[00045] Still another object is to provide a compound which has stable behavior over a wide range of temperatures, pressures and over a long time span.

[00046| The other objects and advantages of the present invention will be apparent from
the following description when read in conjunction with the accompanying drawings which are
incorporated for illustration of preferred embodiments of the present invention and are not
intended to limit the scope thereof.
5 STATEMENT OF INVENTION
[00047} Accordingly the invention provides a lead titanate based compound, particularly a Lead-Barium-Strontium-Titanate compound. In particular the present invention provides a lead barium strontium compound having a chemical composition expressed by compositional formula, Pb1-xBa0.5xSr0.5xTiO3, where x takes values greater than 0.0 and less than 1.0 Still more 10 particularly, the present invention provides a ferroelectric Lead-Bariurn-Strontium-Titanate compound for use in transducers as sensing element and in capacitors as a dielectric, whereas in data storage devices as a memory element, wherein the PBST compound is characterized by having a high dielectric constant, low dielectric loss, low porosity, high mechanical strength and remnant polarization. The PBST may be in the form of a pellet, bulk material, a thin film or any 15 other suitable form, shape and size.
[00048] in accordance with one embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium strontium titanate compound have the chemical composition expressed by compositional formula, Pb1-xBao 5xSr0 5xTi0 , where x takes values greater than 0.0 and less than 1.0 In accordance with 20 the present invention the method of fabricating the lead barium strontium titanate compound comprises the steps of:
a. providing starting materials including a lead containing compound, a barium
containing compound, a strontium containing compound and a titanium containing
compound in predetermined stoichiometric ratio to form a mixture thereof;
25 b. grinding the said mixture for a first predetermined time period t1 to reduce the
intermolecular distance, resulting in the formation of first grinded mixture;
c. heating said first grinded mixture at a first predetermined temperature T1 for a
predetermined time period t'1 wherein said lead containing compound, barium
containing compound, strontium containing compound and titanium containing
30 compound are decomposed or fragmented at molecular level into lead and its other
part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture;
d. grinding said first heated mixture for a second predetermined time t2 to facilitate the
solid state reaction, resulting in formation of second grinded mixture;

e. heating second grinded mixture at a second predetermined temperature T2 for a
second predetermined time f2 wherein said lead containing compound, barium
containing compound, strontium containing compound and titanium containing
compound are fragmented at molecular level into lead and its other part, barium and
5 its other part, strontium and its other part and titanium and it other part, and thus
forming a more homogenized compound by solid state reaction, resulting in formation of second heated mixture;
f. grinding said second heated mixture for a third predetermined time t3, again to
facilitate the solid state reaction, forming third grinded mixture;
10 g. mixing a suitable binder to said third grinded mixture;
h. forming pellets or blocks or any other form of suitable shape and dimensions and
weight by application of a predetermined pressure using a mold; i. heating said pellets or blocks or any other form, at a third predetermined temperature
TPl for third predetermined time period t'Pl that removes binding element, wherein a
15 single phase lead barium strontium titanate compound formation is completed and the
pellets or blocks or any other form of the compound may be used in capacitors,.
memory elements or transducers.
[00049] In accordance with another embodiment of the present invention, a method of
fabricating the lead barium strontium titanate compound is provided, wherein the lead barium
20 strontium titanate compound has the chemical composition expressed by compositional formula,
Pb1-xBao.5xSro0.5XTiO3, where x takes values greater than 0.0 and less than 1.0. The method of
fabricating the lead barium strontium titanate compound in accordance with this embodiment of
the present invention comprises the steps of:
a. providing starting materials including a lead containing compound, a barium containing
25 compound, a strontium -containing compound and a titanium containing compound in
predetermined stoichiometric ratio to form a mixture thereof;
b. grinding said mixture for a first predetermined time period tr to reduce the mtermolecular
distance, resulting in the formation of first grinded mixture;
c. heating said first grinded mixture at a first predetermined temperature T1 for a
30 predetermined time period t'1 wherein said lead containing compound, barium containing
compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture;

d. grinding said first heated mixture for a second predetermined time t2to facilitate the solid
state reaction, resulting in formation of second grinded mixture;
e. heating second grinded mixture at a second predetermined temperature T2 for a second
predetermined time t'2 wherein said lead containing compound, barium containing
5 compound, strontium containing compound and titanium containing compound are
fragmented at molecular level into lead and its other part, barium and its other part,
strontium and its other part and titanium and it other part, and thus forming a more
homogenized compound by solid state reaction, resulting in formation of second heated
mixture;
10 f. grinding said second heated mixture for a third predetermined time t3, again to facilitate
the solid state reaction, forming third grinded mixture;
g. heating third grinded mixture at a third predetermined temperature T3 for a third
predetermined time t'3 wherein the second heated mixture gets more homogenized,
resulting in formation of third heated mixture;
15 h. grinding said third heated mixture for a fourth predetermined time t4, again to facilitate
the solid state reaction, forming fourth grinded mixture; i. mixing a suitable binder to said fourth grinded mixture;
j. forming pellets or blocks or any other form of suitable shape and dimensions and weight
by application of a predetermined pressure using a moid;
20 k. heating said pellets or blocks or any other form, at a fourth predetermined temperature
Tp2 for fourth predetermined time period t'p2that removes binding element, wherein the a
single phase lead barium strontium titanate compound formation is completed and the
pellets or blocks or any other form of the compound may be used in capacitors, memory
elements or transducers.
25 [00050] These and other aspects of the embodiments herein will be better appreciated and
understood when considered in conjunction with the following description and the accompanying
drawings. It should be understood, however, that the following descriptions, while indicating
preferred embodiments and numerous specific details thereof, are given by way of illustration and
not of limitation. Many changes and modifications may be made within the scope of the
30 embodiments herein without departing from the spirit thereof, and the embodiments herein
include all such modifications.
BRIEF DESCRIPTION OF FIGURES

This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which: [00051] FIGURE 1 is a flow chart illustrating the method of fabricating the inventive 5 lead barium strontium titanate compound in accordance with one embodiment of the present invention;
[00052] FIGURE 2 is a flow chart illustrating the method of fabricating the inventive
lead barium strontium titanate compound in accordance with another embodiment of the present
invention;
10 [00053] FIGURE 3 illustrates graphs of variation of dielectric constant (e) of the
inventive lead barium strontium titanate compound at various temperatures as a function of frequency for x = 0.0 to x = 1.0 with the interval of 0.2.
[00054] FIGURE 4 illustrates graphs of variation of dielectric constant (E) of the inventive lead barium strontium titanate compound at various frequencies as a function of 15 temperature for x = 0.0 to x — 1.0 with the interval of 0.2.
l00055J FIGURE 5 illustrates graphs of variation of dielectric Joss (tan δ) of the inventive lead barium strontium titanate compound at various temperatures as a function frequency for x = 0.0 to x = 1.0 with the interval of 0.2.
[00056] FIGURE 6 illustrates a graph of variation of the porosity of the inventive lead 20 barium strontium titanate compound as a function of x value, wherein x takes values from 0.0 to 1.0;
[00057] FIGURE 7 illustrates a graph of variation, of the transition temperature of the
inventive lead barium strontium titanate compound as a function of x value, wherein x takes
values from 0.0 to 1.0.
25 DETAILED DESCRIPTION OF INVENTION
[00058] The embodiments herein, the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the 30 embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[00059] The inventors have conducted extensive investigations with the above mentioned
objects in an approach to discover a lead titanate compound with simultaneous substitution of
barium and strontium, wherein the said lead titanate compound exhibits an improved dielectric
behavior along with reduced dielectric loss, reduced porosity, enhanced mechanical strength and
5 a remnant polarization.
[00060] The embodiments herein achieve a ferroelectric lead barium strontium titanate
compound having the chemical composition expressed by the compositional formula Pb1-
xBao 5XSr0.5xTiO3,where x takes values greater than 0.0 and less than 1.0, wherein the lead barium
strontium titanate compound exhibits a high dielectric constant, a low dielectric loss, a low
10 porosity, high mechanical strength and remnant polarization.
[00061] In accordance with the present invention, the inventors have observed that substitution of barium influences dielectric properties of the compound. The inventors have observed a pronounced effect of barium substitution on the dielectric properties
[00062] In accordance with the present invention, it is observed that the substitution of 15 strontium reduces the porosity and shifts the transition temperature towards ambient temperature, particularly when the percentage of strontium was 30%, minimum value of porosity was observed with lead contained ceramic, that is, when the value of x was 0.6.
[00063] In accordance with one embodiment of the present invention, a method of
fabricating the lead barium strontium titanate compound is provided, wherein the lead barium
20 strontium titanate compound have the chemical composition expressed by the compositional
formula, Pb1-xBao.5xSro.5xTiO3, where x takes values greater than 0.0 and less than 1.0. Referring
to FIGURE I, wherein the method of is depicted in form of flow chart 101, the method of
fabricating the lead barium strontium tttanate compound in accordance with the present invention
comprises the steps of:
25 a. starting materials including a lead containing compound, a barium containing compound,
a strontium containing compound and a titanium containing compound in predetermined
stoichiometric ratio to form a mixture thereof 102;
b. grinding the said mixture for a first predetermined time period t1 to reduce the
intermolecular distance, resulting in the formation of first grinded mixture 103;
30 c. heating said first grinded mixture at a first predetermined temperature T1 for a
predetermined time period t'1 wherein said lead containing compound, barium containing compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its

other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture 104; d. grinding said first heated mixture for a second predetermined time t2 to
facilitate the solid
state reaction, resulting in formation of second grinded mixture 105;
5 e. heating second grinded mixture at a second predetermined temperature T2 for a second
predetermined time t2 wherein said lead containing compound, barium containing
compound, strontium containing compound and titanium containing compound are
fragmented at molecular level into lead and its other part, barium and its other part,
strontium and its other part and titanium, and it other part, and thus forming a more
10 homogenized compound by solid state reaction, resulting in formation of second heated
mixture 106;
f. grinding said second heated mixture for a third predetermined time t3, again to facilitate
the solid state reaction, forming third grinded mixture 107;
g. mixing a suitable binder to said third grinded mixture 108;
15 h. forming pellets or blocks or any other form of suitable shape and dimensions and weight
by application of a predetermined pressure using a mold 109; i. heating said pellets or blocks or any other form, at a third predetermined temperature Tp1
for third predetermined time period t'P1 that removes binding element, wherein a single
phase lead barium strontium titanate compound formation is completed 110 and the
20 pellets or blocks or any other form of the compound may be used in capacitors, memory
elements or transducers.
[00064] In accordance with one embodiment of the present invention, the lead containing compound is lead oxide.
(00065] In accordance with one embodiment of the present invention, the barium 25 containing compound is barium carbonate.
[00066] In accordance with one embodiment of the present invention, the strontium containing compound is strontium carbonate.
[00067] In accordance with one embodiment of the present invention, the titanium
containing compound is titanium oxide.
30 [00068] In accordance with one embodiment of the present invention, the grinding of
mixtures including the mixture, the first heated mixture and the second heated mixture is carried out using an "agate mortar".
[00069] In accordance with one embodiment of the present invention, the predetermined grinding time t1 is from about 60 minutes to 180 minutes.

[00070] In accordance with one preferred embodiment of the present invention, the predetermined grinding time t1 is 120 minutes.
[00071] In accordance with one embodiment of the present invention, the first grinded mixture is heated to a temperature T1 wherein T1 ranges from about 723 K to about 1023 K; most 5 preferably T1 is 873 ± 10 K.
[00072] In accordance with one embodiment of the present invention, the first time period for heating the first grinded mixture t'1, wherein t1 ranges from about 360 minutes to about 600 minutes, most preferably t'1 is 480 ±15 minutes.
[00073] In accordance with one embodiment of the present invention, the predetermined 10 grinding time t2 is from about 60 minutes to about 180 minutes, and most preferably t2 is 120 minutes.
[00074] In accordance with one embodiment of the present invention, the second grinded
mixture is heated to a temperature T2, wherein T2 canges from 923 K to about 1223 K; most
preferably T2 is 1073 ± 10 K.
15 [00075] In accordance with one embodiment of the present invention, the second time
period for heating the first grinded mixture t2 ranges from about 240 minutes to about 480 minutes, most preferably t'2 is 360 ± 15 minutes.
[00076] In accordance with one embodiment of the present invention, the grinding time for second heated mixture t3 ranges from about 60 minutes to about 180 minutes, and most 20 preferably t3 is .120 minutes.
[00077] In accordance with one embodiment of the present invention, the pressure applied during molding of pellets ranges from 0.1 tons to 10 tons, preferably from 3 to 8 tons, most preferably the pressure is 6 ton.
[00078] In accordance with one embodiment of the present invention, the binder used for 25 binding the third grinded mixture is polyvinyl alcohol.
[00079] In accordance with one embodiment of the present invention, the pellets or blocks are heated to the temperature TPl ranging from about 873 K to about 1423 K and most
preferably Tp1, is 1273 ± 10 K.
[00080] In accordance with one embodiment of the present invention, the pellets or 30 blocks are heated to the third temperature TP1 for a predetermined time t'P1. wherein t'P1 ranges from about 300 minutes to about 420 minutes and most preferably t' Pl is 360 minutes.
[00081] In accordance with one embodiment, the pellets have a diameter ranging from 8 mm to about 10 and thickness ranging from about 1 mm to about 3 mm.

[00082] In accordance with another embodiment of the present invention, a method of fabricating the lead barium strontium titanate compound is provided, wherein the lead barium strontium titanate compound have the chemical composition expressed by compositional formula, Pb|.xBao 5)CSr0 5ltTi03, where x takes values greater than 0.0 and less than 1.0 Referring to FIGURE 5 2, which depicts a flow chart 20 i for the method for fabrication of the PBST compound in accordance with another embodiment of the present invention, the method of fabricating the lead barium strontium titanate compound in accordance with another embodiment of the present invention comprises the steps of:
a. providing starting materials including a lead containing compound, a barium containing
10 compound, a strontium containing compound and a titanium containing compound in
predetermined stoichiometric ratio to form a mixture thereof 202;
b. grinding said mixture for a iirst predetermined time period tT to reduce the intermolecular
distance, resulting in the formation of first grinded mixture 203;
c. heating said first grinded mixture at a first predetermined temperature T] for a
15 predetermined time period t'i wherein said lead containing compound, barium containing
compound, strontium containing compound and titanium containing compound are decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture 204;
20 d. grinding said first heated mixture for a second predetermined time %2 to facilitate the solid
state reaction, resulting in formation of second grinded mixture 205;
e. heating second grinded mixture at a second predetermined temperature T2 for a second
predetermined time t'2 wherein said lead containing compound, barium containing
compound, strontium containing compound and titanium containing compound are
25 fragmented at molecular level into lead and its other part, barium and its other part,
strontium and its other part and titanium and it other part, and thus forming a more
homogenized compound by solid state reaction, resulting in formation of second heated
mixture 206;
f grinding said second heated mixture for a third predetermined time t?, again to facilitate
30 the solid state reaction, forming third grinded mixture 207;
g. heating third grinded mixture at a third predetermined temperature T3 for a third predetermined time t'j wherein the second heated mixture gets more homogenized, resulting in formation of third heated mixture 208;

h. grinding said third heated mixture for a fourth predetermined time t1, again to facilitate
the solid state reaction, forming fourth grinded mixture 209; i. mixing a suitable binder to said fourth grinded mixture 210;
j. forming pellets or blocks or any other form of suitable shape and dimensions and weight
5 by application of a predetermined pressure using a mold 211;
k. heating said pellets or blocks or any other form, at a fourth predetermined temperature
Tp2 for fourth predetermined time period t'?2 that removes binding element, wherein the
single phase lead barium strontium titanate compound formation is completed 212 and
the pellets or blocks or any other form of the compound may be used in capacitors,
10 memory elements or transducers.
[00083] In accordance with one embodiment of the present invention, the time period t1 for grinding said mixture ranges from about 60 minutes to about 180 minutes and most preferably t1 is about 120 minutes.
[00084] In accordance with one embodiment of the present invention, the first grinded 15 mixture is heated to first predetermined temperature T1 ranging from about 723 K to about 1023 K and most preferably T1 is 873 ± 10 K.
[00085] In accordance with one embodiment of the present invention, the first grinded mixture is heated to first predetermined temperature T1 for a predetermined time period t'1, wherein t'1 ranges from about 360 minutes to about 600 minutes, most preferably t'1 is 480 ±15 20 minutes.
[00086] In accordance with one embodiment of the present invention, the predetermined grinding time -t2 is from about 60 minutes to about 180 minutes, and most preferably t2 is 120 minutes.
[00087] In accordance with one embodiment of the present invention, the second grinded 25 mixture is heated to a temperature T2; wherein T2 ranges from 923 K to about 1223 K, most preferably T2 is 1073 ± 10 K
[00088] In accordance with one embodiment of the present invention, the second time
period for heating the first grinded mixture t'2 ranges from about 240 minutes to about 480
minutes, most preferably t2 is 360 ± 15 minutes.
30 [00089] In accordance with one embodiment of the present invention, the said second
heated mixture is grinded for a third predetermined time t3, wherein t3 ranges from about 60 to about 180 minutes; most preferably t3 is 120 minutes.

[00090] In accordance with one embodiment of the present invention, the said third grinded mixture is heated to a third predetermined temperature T3, wherein T3 ranges from about 1023 K to about 1423 K, and most preferably T3 is 1273 ± 10 K.
[00091] In accordance with one embodiment of the present invention, the third grinded 5 mixture is heated to a third predetermined temperature T3 for a third predetermined time t'3, wherein t'3 ranges from about 240 to about 480 minutes and most preferably t'3 is about 360 ± 15 minutes.
[00092] In accordance with one embodiment of the present invention, the said third mixture is grinded for a fourth predetermined time t4, wherein t4 ranges from about 60 minutes to 10 about 180 minutes and most preferably 120 minutes.
[00093] In accordance with one embodiment of the present invention, the said binder mixed said third grinded mixture is polyvinyl alcohol.
[00094] In accordance with one embodiment of the present invention, the pellets have a thickness ranging from about I mm to about 3 mm and diameter ranging from about 8 to about 10 15 mm.
[00095] In accordance with one embodiment of the present invention, the pellets have weight ranging from about gm to about 5 gm.
[00096] In accordance with one embodiment of the present invention, the pellets are formed by application of pressure, wherein the pressure applied ranges from about 0.1 ton to 20 about 10 ton, preferably from about 3 to about 8 tons and most preferably the pressure is 6 ton.
[00097] In accordance with one embodiment of the present invention, the pellets are heated to a predetermined temperature Tp2, wherein Tp2 ranges from about 1273 K to 1673 K; and
most preferably Tp2 is 1473 K;
[00098] In accordance with one embodiment of die present invention, the pellets are 25 heated to a fourth predetermined temperature Tp for a fourth predetermined time period t'p, wherein t'p ranges from about 120 to about 360 minutes and most preferably 240 minutes.
[00099] In one preferred embodiment the lead containing compound is lead oxide (PbO) with very high purity, preferably greater than 99.9 %.
[000100] In one preferred embodiment the barium containing compound is barium 30 carbonate (BaCO3) having very high purity, preferably greater than 99.9 %.
[000101] In one preferred embodiment the strontium containing compound is strontium carbonate (S1CO3) having purity greater than 99.9 %.
[000102] In one preferred embodiment the titanium containing compound is titanium oxide (Ti02) with purity greater than 99.9 %.

[000103] In accordance with one embodiment of the present invention, the invetnive lead barium strontium ptanate compound having the chemical composition expressed by compositional formula Pb1-xBao.5xSro.5XTiO3, exhibits a surprisingly high dielectric constant ranging from about l84 to about 3022, particularly, when x takes values between greater than 0.0 5 and less than 1.0, wherein the dielectric constant was measured using commercially available instrument from HP with model number HP 4284A LCR Q meter. Typical minimum and maximum values of the dielectric constant at particular temperature & frequency as a function of x values are tabulated in table 1 below. The graphs of variation of dielectric constant of the inventive PBST compound with change in value of x as a function of frequency at various 10 temperatures are illustrated in FIGURE 3 and FIGURE 4.
[000104] The dielectric constant is observed to decrease with increasing frequency. It attains almost stable value at higher frequencies.
[000105] The dielectric constant is observed to increase initially with rise in temperature up to the transition temperature, Tc. With further rise in temperature, the dielectric constant shows
15 a decreasing trend.
TABLE 1

SAMPLE X COMPOUND DIELECTRIC CONSTANT (□)

εmax FREQ TEMP
(K) εmax FREQ (Hz) TEMP
(K)
I 0.0 PbTiO3 393 106 623 9222 100 763
II 0.2 Pb0.8Ba0.1Sr0.1TiO3 245 10s 623 3022 100 708
III 0.4 Pb0.6Ba0.2Sr0.1TiO3 187 106 723 1641 100 583
IV 0.6 Pb0.6Ba0.3Sr0.3TiO3 201 106 373 510 100 518
V 0.8 Pb0.2Ba0.4Sr0.4TiO3 184 106 303 414 100 423
VI 1.0 Ba0.5Sr0.5TiO3 163 106 448 364 100 303
[000106] The inventors found that the high dielectric constant of the lead barium strontium titanate compound having the chemical composition expressed by compositional
20 formula Pb1-xBao.5xSro.5xTi03, wherein x takes values greater than 0.0 and 1.0 may be attributed to the fact that ferroelectric crystals possess regions with uniform polarization called ferroelectric domains. Within a domain, all the electric dipolcs arc aligned in the same direction. There may be many domains in a crystal separated 6y interfaces called domain walls. A ferroelectric single crystal, when grown, has multiple ferroelectric domains. The dielectric constant of the material
25 increases by domain wall motion.
[000107] The dielectric constant of the lead barium strontium titanate compound having the chemical composition expressed by compositional formula Pb1-xBao.5xSr0.5XTiO3, wherein x

takes values greater than 0.0 and less than 1.0 was measured in pellet formed by using hydraulic press at room temperature.
[000108] In one embodiment of the present invention, the inventive lead barium strontium titanate compound having the chemical composition expressed by compositional
5 formula Pb1-xBao.5xSro.5xTiO3, exhibits low dielectric loss, particularly, when x takes values between 0.0 and 1.0, wherein the dielectric loss was measured using commercially available instrument from HP with model number HP 4284A LCR Q meter. Typical minimum and maximum values of the dielectric loss at particular temperature & frequency as a function of x values are tabulated in table 2 below. The graphs of variation of dielectric loss of the inventive
PBST compound with change in value of x as a function of frequency at various temperatures are illustrated in FIGURE 5. The dielectric loss shows a declining trend with rise in frequency.
TABLE 2

SAMPLE X COMPOUND DIELECTRIC LOSS (tan 6)

tan 5 (mils) FREQ (Hz) TEMP
(K) tan 8 (max) FREQ
(Hz) TEMP
(K)
I 0.0 PbTiO3, 0.13- 106 623 3.26 2000 723
II 0.2 Pbo.8Bao.1Sr0.3TiO3 0.137 106 623 2.33 5000 723
III 0.4 Pbo.6Bao.2Sro.3TiO3 0.128 1O6 623 2.09 1000 673
IV 0.6 Pb0.4Bao.3Sro.3TiO3 0,036 106 623 0.683 1000 723
V 0.8 Pb0.4Ba0.4Sr0.4TiO3 0.0022 106 623 0.748 1000 723
VI 1.0 Ba0.5Sr0.5TiO3 0.02 106 623 0.296 1000 723
[000109] The reduced dielectric loss observed for the inventive lead barium strontium
5 titanate compound having the chemical composition expressed by composition formula Pb1-x-
Bao.5xSr0.5xTi03, is attributed to porosity of the material. Lower porosity results in smaller grain
size which in turn reduces the dielectric loss as relative density and porosity are two important
factors that control the dielectric loss. Also, reduction in domain wall contribution contributes to
the reduction in the loss.
20 [000110] In one embodiment of the present invention, the inventive lead barium
strontium titanate compound having the chemical composition expressed by compositional
formula Pb1-xBao.5xSro.5xTiO3, exhibits low porosity and high mechanical strength, particularly,
when x takes values between 0.6 and 0.8. It is well known that a material with low porosity, in
general, has a high mechanical strength. The variation of porosity as a function of x is depicted in
25 FIGURE 6.
[000111 ] The percentage porosity was calculated using the formula
% porosity = [1 - (pxy/pth)] x 100,

where pexp is the experimental density of the PBST compound under consideration, calculated using water immersion method and pth, is the theoretical density of the PBST compound obtained from X-ray diffractometery analysis of the compound. These calculations are well-known in the art and a reference to the same may be found in the book titled "Elements Of X-ray Diffraction'1 5 by B. D. Cullity, from Addison-Wesley Publishing Company, inC
[000112] Typical values of porosity of the inventive PBST compound are tabulated in table 3 below and are depicted in FIGURE 6, which indicate that the porosity of the inventive PBST compound decrease with increasing dopant concentration.
TABLE 3

SAMPLE I COMPOWTO POROSITY (%)
I 0.0 PbTi3 12
II t).2 Pbo..8Bao..1Sr0..1Ti03 11
III 0.4 Pbo.6Ba0.2Sr0.2TiO3 9
IV 0.6 Pbo.4Bao.3Sro..3TiO3 S
V 0.8 Pb0.2Ba0.4Sro.4TiO3, 8
VI 1.0 Bao.5Sro.5Ti03 7
J X» [000113] The reduction in porosity can be attributed tp the doping of smaller Sr2+ ion at
the Pb site.
[000114] In accordance with one embodiment of the foresent invention, the inventive lead
barium strontium titanate compound is observed to exhibit piezoelectric nature that is, the
material has ability to develop an electrical charge proportional to a mechanical stress.
15 |000115] In accordance with one embodiment of the present invention, the inventive
lead barium strontium titanate compound is observed to exhibit paraelectric nature above the
Curie temperature, wherein the Curie temperature depends upon the composition. Above the
transition temperature, ferroelectric materials become paraelentries.
(000116] The transition temperatures refer to the temperature corresponding to the 20 dielectric maxima, in the plot depicting variation of dielectric constant with temperature, given by
FIGURE 6.
[000117] Typical transition temperatures for the inventive PBST compound of the
present invention, are tabulated in table 4 below, the same is depicted in graphical form in
FIGURE 7.
25 TABLE 4

SAMPLE X COMPOUND TRANSITION TEMPERATURE (Kelvin)
I 0.0 PbTiO, 763
n 0.2 Pb0.8Ba0.1Sr0.8TiO3 435

II 0-4 Pb0.6Ba0.2Sr0.2TiO3 583
IV 0.6 Pb0.4Ba0.3Sr0.3TiO3 518
V 0.8 Pb0.2Ba0.4Sr0.4TiO3
423
vi 1.0 Ba0.5Sr0.5TiO3 BELOW ROOM TEMPERATURE
[000118] In accordance with one embodiment of the present invention, the inventive lead barium strontium titanate compound is observed to have perovskite structure, which has been Confirmed by X-ray diffractometry.
[0001 \9\ In accordance with one embodiment of the present invention, the inventive lead 5 barium strontium titanate compound having a high dielectric constant may used in a capacitor comprising at least a pair of conductor plates and a dielectric material film or slab between the pair of said conductor plates, the dielectric material film or slab being constructed from a lead barium strontium titanate compound with chemical composition Pbi.xBao.5xSrosxTi03, wherein x takes values greater than 0.0 and less than 1.0.
10 J000120} In accordance with one embodiment of the present invention, the inventive lead
barium strontium titanate compound exhibits a dielectric constant m die range from about 184 to about 3022.
|000121) In accordance wuh one embodiment of the present invention, the inventive lead barium strontium titanate compound exhibits a dielectric loss less than about 0.19 at frequencies
15 greater than about 10 kHz.
[000122] In accordance with one embodiment of the present invention, a capacitor comprising at least a pair of conductor plates and a dielectric material film or slab between the pair of said conductor plates is disclosed, wherein the dielectric material film or slab being constructed from a lead barium strontium titanate compound with chemical composition Pbi-
20 xBao ^xSros^TiO^ wherein x takes values greater than 0.0 and Jess than J.0, wherein the dielectric material film or slab has a dielectric constant in the range from 184 to 3022.
[000123] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from
25 the generic concept, and, tiierefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, whde the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments
30 herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

We Claim-
1. A lead barium strontium titanate compound having a chemical composition expressed by
compositional formula Pb1-xBao.5xSro.5xTi03 wherein x takes values greater than 0.0 and
less than 1.0, and exhibiting a dielectric constant, a dielectric loss, a porosity, a remnant
5 polarization and a transition temperature.
2. The lead barium strontium titanate compound of claim 1, wherein said compound
exhibits the said dielectric constant in the range from about 184 to about 3022, the said
dielectric loss of less than about 0.19 at frequencies greater than 10 kHz, the said porosity
in the range from about 7 % to about 12 % and the said transition temperature ranging
10 from about below room temperature to about 763 K.
3. A method of fabricating the lead barium strontium titanate compound comprising the
steps of:
a. providing starting materials including a lead containing compound, a barium containing
compound, a strontium containing compound and a titanium containing compound in
15 predetermined stoichiometric ratio to form a mixture thereof;
b. grinding the said mixture for a first predetermined time period t1 to reduce the
intermolecular distance, resulting in the formation of first grinded mixture;
c. heating said first grinded mixture at a first predetermined temperature T1 for a
predetermined time period t'1 wherein said lead containing compound, barium containing
20 compound, strontium containing compound and titanium containing compound are
decomposed or fragmented at molecular level into lead and its other part, barium and its other part, strontium and its other part and titanium and it other part, resulting in the formation of first heated mixture;
d. grinding said first heated mixture for a second predetermined time t2to facilitate the solid
25 state reaction, resulting in formation of second grinded mixture;
e. heating second grinded mixture at a second predetermined temperature T2 for a second
predetermined time t'2 wherein said lead containing compound, barium containing
compound, strontium containing compound and titanium containing compound are
fragmented at molecular level into lead and its other part, barium and its other part,
30 strontium and its other part and titanium and it other part, and thus forming a more
homogenized compound by solid state reaction, resulting in formation of second heated mixture;
f. grinding said second heated mixture for a third predetermined time t3, again to facilitate
the solid state reaction, forming third grinded mixture;

£5

1 \i

g. mixing a suitable binder to said third grinded mixture;
h. forming pellets or blocks or any other form of suitable shape and dimensions and weight
by application of a predetermined pressure using a mold;
i. heating said pellets or blocks or any other form, at a predetermined temperature TP1 for
5 predetermined time period t'Pl that removes binding element and forms a single phase
compound, thereby forming heated pellets or blocks or thin films.
4. The method of claim 3, wherein after performing step (f) additional steps of;
i. heating said third grinded mixture to a third predetermined temperature T3 and
for third predetermined time t'3 resulting in formation of third heated mixture;
10 and
ii. grinding said third heated mixture for a predetermined time μ resulting in formation of fourth grinded mixture followed by; g. mixing a suitable binder to said fourth grinded mixture;
h. forming pellets or thin films or blocks of suitable dimensions and weight by application
15 of a predetermined pressure using a mold;
i. heating said pellets or thin films or blocks at a predetermined temperature Tp for third predetermined time period t'p that removes binding element and forms a single phase compound, thereby forming pellets or blocks or thin films.
5. The method of claim 3, wherein said predetermined grinding time t1 is from about 60
20 minutes to 180 minutes, said first grinded mixture is heated to a temperature T1 wherein
T1 ranges from about 723 K to about 1023 K, and said predetermined first time period for heating the first grinded mixture t1 ranges from about 360 minutes to about 600 minutes.
6. The method of claim 3, wherein said predetermined second grinding time t2 is from about
60 minutes to about 180 minutes, said second grinded mixture is heated to a temperature
25 T2, wherein T2 ranges from 923 K to about 1223 K and said second predetermined time
period for heating the first grinded mixture t'2 ranges from about 250 minutes to about 500 minutes.
7. The method of claim 3, wherein, said third predetermined grinding time for second
heated mixture t3 ranges from about 60 minutes to about 180 minutes.
30 8. The method of claim 3, wherein said pressure applied during formation of pellets ranges
from 0.1 tons to 10 tons. 9. The method of claim 3, wherein said pellets or blocks are heated to the temperature Tp ranging from about 873 K to about 1423 K and said pellets or blocks arc heated to the
25

temperature TPl for a predetermmed time t'p, wherein t'p ranges from about 120 minutes to
about 360 minutes. 10, The method of claim 4, wherein said third grinded mixture is heated to a temperature T3 ranging from about 1023 K to about 1423 K, for a time f 3 ranging from about 240 to 480 minutes, said third heated mixture is grinded for a fourth predetermined time t4 forming fourth grinded mixture and said pellets or blocks are heated to the temperature Tp
ranging from about 1273 K to about 1673 K for a predetermined time t'p, wherein t'p ranges from about 120 minutes to about 360 minutes.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=HxpLOr/eYFdG2pojpKGMYA==&loc=vsnutRQWHdTHa1EUofPtPQ==

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Patent Number

270208

Indian Patent Application Number

205/MUM/2010

PG Journal Number

49/2015

Publication Date

04-Dec-2015

Grant Date

02-Dec-2015

Date of Filing

25-Jan-2010

Name of Patentee

BABASAHEB AMBEDKAR MARATHWADA UNIVERSITY,AURANGABAD

Applicant Address

AURANGABAD, MAHARASHTRA, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	GOVIND KISHANRAO BICHILE	FLAT NO 2,PADMAVATI APARTMENT, ADINATH NAGAR,AURANGABAD, INDIA.
2	PRANAV PRAMODRAO BARDARPURKAR	FLAT NO.3,MALKHARE COMPLEX, PADAMPURA,AURANGABAD, INDIA.
3	SUHAS MOHANRAO DESAI	FLAT NO.5,AKASH APARTMENT, SHREYANAGAR,AURANGABAD, INDIA.
4	KAMALAKAR MAROTRAO JADAV	K-5,MILAN NAGAR, CIDCO N-5,AURANGABAD, INDIA.

PCT International Classification Number

C04B35/46; C04B 35/468; C04B 35/47

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA