Title of Invention	"A PROCESS FOR PREPARATION OF A BARIUM TITANATE BASED COMPOSITION HAVING MEDIUM DIELECTRIC CONSTANT AND TEMPERATURE STABILITY"
Abstract	The present invention provides a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder; adding 0.75 - 2.0 wt.% (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder ;adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5, and CO3O4 to BaTiO3 powder; mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80, wt% ( of powder mix) % and distilled water for 10 - 20 h; drying the mixture at 100-150°C in an oven for 2 -4 h; calcining the mixture at 600-800°C for 5-10 h ; dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10 h. to obtain the said composition.

Title of Invention

"A PROCESS FOR PREPARATION OF A BARIUM TITANATE BASED COMPOSITION HAVING MEDIUM DIELECTRIC CONSTANT AND TEMPERATURE STABILITY"

Abstract

The present invention provides a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder; adding 0.75 - 2.0 wt.% (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder ;adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5, and CO3O4 to BaTiO3 powder; mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80, wt% ( of powder mix) % and distilled water for 10 - 20 h; drying the mixture at 100-150°C in an oven for 2 -4 h; calcining the mixture at 600-800°C for 5-10 h ; dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10 h. to obtain the said composition.

Full Text	This invention relates to a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability and the said composition is useful for making low fire multilayer ceramic capacitors. This invention particularly relates to improved barium titanate (BaTi03) based composition which is lead and rare-earth free, showing medium dielectric constant value and temperature stability over a wide range and are useful for making low-fire multilayer ceramic capacitors. The uniqueness of the present invention lies in the fact that the improved composition eliminates the necessity of any hazardous lead compound or costly rare-earth compounds in the powder mix, whereas similar existing compositions contain either toxic lead compounds or costly rare-earth compounds. Various dielectric compositions standardised and coded have got typical applications. Low-fire, medium dielectric constant capacitor compositions showing a temperature stability whithin a specific range (variation of capacitance between - 55°C and + 125°C should be within + /- 15%) are generally coded as X7R type. They are used for bypass decoupling in radio and television receivers, computers, serovo-systems etc., where moderate capacitance variations with temperature are permissible and dissipation factor is not critical. In this connection, reference may be made to the following publications: 1. I. Matsuzaki, N. Shimizu and S. Yamada "High permittivity 2700 (in the disc form) and dissipation factors 0.05 to 0.01 (at 1kHz and IV RMS). Still another object is to provide lead and rare-earth free barium titanate based dielectric composition showing dielectric constant variations (from its room temperature value) over the temperature range - 55 ºC to + 125º C within +/- 25%. Yet another object is to provide lead and rare-earth free barium titanate .based dielectric composition which can be sintered at 1140 +/- 20 ºC making them compatible with 70/30 Ag/Pd electrode. Another object is to provide a process for preparing a powder mix of the composition of the present invention. Accordingly, the present invention provides a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising: adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder adding 0.75 - 2.0 wt.% (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5, and CO3O4 to BaTiO3 powder; mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80, wt% ( of powder mix) % and distilled water for 10 - 20 h; drying the mixture at 100-150°C in an oven for 2 - 4 h; calcining the mixture at 600-800°C for 5-10 h ; dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10 h. to obtain the said composition. In an embodiment of the present invention the flux used is of laboratory reagent grade and consist of 0 -0.8 wt. % Li2C2O4, 0.3-2.0 wt% Li2B4O7, 0.5-2.0 wt % H3BO3 and 0-0.6 wt% Bi2O3 ( of barium titanate). In another embodiment of the present invention the grain growth inhibitor and curie peak suppressor used are of laboratory reagent grade and consists of 0.5 -0 1..5 wt.% Nb2O5, 0-1.0 wt. % Bi2 (SnO3)3 and 0-1.0 wt.% Bi4Ti3O12 ( of barium titanate). In yet another embodiment of the present invention the acceptor dopant is of laboratory reagent grade and consists of 0.01 - 0.15. wt % Mno2, 0-1.0 wt% NiO, 0-0.1 wt% CuO, 0-oTl wt % of V2 O5 and 0-0.1 wt % CO3O4 (of barium titanate); In still another embodiment of the present invention, the composition as prepared comprises barium titanate (BaTiO3); 0.3 - 2.0 wt.% (of BaTiO3) flux containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3; 0.75 - 2.0 wt.% of (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12; 0.03 - 0.2 wt.% (BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5 and Co3O4. The composition of the present invention is not a mere admixture but a synergistic mixture having properties which are different from the mere aggregated properties of the individual ingredients. The following examples illustrate the invention and the manner in which it may be carried out in practice; however, this should not be construed to limit the scope of the present invention. Example 1. A batch composition containing 23.09 g BaTiO3 0.27 g Nb205, 0.08 g Li2C204, 0.17 g H3B03 , 0 . 04 g NiO and 0.03 g Mn02 was prepared by mixing the aforesaid powders with 16 g of distilled water in a ball mill (agate grinding medium) for 15 h. The mixed slurry was dried at 150°C in an oven for 4h. The dried mixture was calcined at 600°C for 10 h followed by dry grinding in a ball mill for 6 h to get the capacitor composition (mixed powder). For testing, pellets of mixed powder (10 mm dia and 2-3 mm thickness) were made by uniaxial pressing (pressure 50 MPa) using We Claim: 1. A process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising: a) adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder b) adding 0.75 - 2.0 wt.% (BaTiOs) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder c) adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5, and CO3O4 to BaTiO3 powder; d) mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80, wt% ( of powder mix) % and distilled water for 10 - 20 h; e) drying the mixture at 100-150°C in an oven for 2 - 4 h; f) calcining the mixture at 600-800°C for 5-10 h ; g) dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10 h. to obtain the said composition. 2. A process as claimed in claim 1, wherein the flux used is of laboratory reagent grade and consist of 0 -0.8 wt. % Li2C2O4, 0.3-2.0 wt% Li2B4O7, 0.5-2.0 wt % H3BO3 and 0-0.6 wt% Bi2O3 ( of barium titanate). 3. A process as claimed in claim 1 , wherein the grain growth inhibitor and curie peak suppressor used are of laboratory reagent grade and consists of 0.5 -0 1..5 wt.% Nb2O5, 0-1.0 wt. % Bi2 (SnO3)3 and 0-1.0 wt.% Bi4Ti3O12 ( of barium titanate). 4. A process as claimed in claim 1 , wherein the acceptor dopant is of laboratory reagent grade and consists of 0.01 - 0.15. 5. A process as claimed in claim 1 , wherein the composition so obtained comprises: i) barium titanate (BaTiO3); ii) 0.3 - 2.0 wt.% (of BaTiO3) flux containing Li2C2O4. Li2B4O7. H3BO3 and Bi2O3; iii) 0.75 - 2.0 wt.% of (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12', iv) 0.03 - 0.2 wt.% (BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5 and Co3O4. 6. A process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability substantially as herein described with reference to the examples accompanying the specification.

Full Text

This invention relates to a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability and the said
composition is useful for making low fire multilayer ceramic capacitors.
This invention particularly relates to improved barium titanate (BaTi03) based composition which is lead and rare-earth free, showing medium dielectric constant value and temperature stability over a wide range and are useful for making low-fire multilayer ceramic capacitors.
The uniqueness of the present invention lies in the fact that the improved composition eliminates the necessity of any hazardous lead compound or costly rare-earth compounds in the powder mix, whereas similar existing compositions contain either toxic lead compounds or costly rare-earth compounds.
Various dielectric compositions standardised and coded have got typical applications. Low-fire, medium dielectric constant capacitor compositions showing a temperature stability whithin a specific range (variation of capacitance between - 55°C and + 125°C should be within + /- 15%) are generally coded as X7R type. They are used for bypass decoupling in radio and television receivers, computers, serovo-systems etc., where moderate capacitance variations with temperature are permissible and dissipation factor is not critical.
In this connection, reference may be made to the following publications: 1. I. Matsuzaki, N. Shimizu and S. Yamada "High permittivity

2700 (in the disc form) and dissipation factors 0.05 to 0.01 (at 1kHz and IV RMS).
Still another object is to provide lead and rare-earth free barium titanate based dielectric composition showing dielectric
constant variations (from its room temperature value) over the
temperature range - 55 ºC to + 125º C within +/- 25%.
Yet another object is to provide lead and rare-earth free
barium titanate .based dielectric composition which can be
sintered at 1140 +/- 20 ºC making them compatible with 70/30
Ag/Pd electrode.
Another object is to provide a process for preparing a powder mix
of the composition of the present invention.
Accordingly, the present invention provides a process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising:
adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder
adding 0.75 - 2.0 wt.% (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder
adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5, and CO3O4 to BaTiO3 powder;

mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80, wt% ( of powder mix) % and distilled water for 10 - 20 h;
drying the mixture at 100-150°C in an oven for 2 - 4 h; calcining the mixture at 600-800°C for 5-10 h ;
dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10 h. to obtain the said composition.
In an embodiment of the present invention the flux used is of laboratory reagent grade and consist of 0 -0.8 wt. % Li2C2O4, 0.3-2.0 wt% Li2B4O7, 0.5-2.0 wt % H3BO3 and 0-0.6 wt% Bi2O3 ( of barium titanate).
In another embodiment of the present invention the grain growth inhibitor and curie peak suppressor used are of laboratory reagent grade and consists of 0.5 -0 1..5 wt.% Nb2O5, 0-1.0 wt. % Bi2 (SnO3)3 and 0-1.0 wt.% Bi4Ti3O12 ( of barium titanate).

In yet another embodiment of the present invention the acceptor dopant is of laboratory reagent grade and consists of 0.01 - 0.15. wt % Mno2, 0-1.0 wt% NiO, 0-0.1 wt% CuO, 0-oTl wt % of V2 O5 and 0-0.1 wt % CO3O4 (of barium titanate);
In still another embodiment of the present invention, the composition as prepared comprises barium titanate (BaTiO3); 0.3 - 2.0 wt.% (of BaTiO3) flux containing Li2C2O4, Li2B4O7, H3BO3 and Bi2O3; 0.75 - 2.0 wt.% of (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12; 0.03 - 0.2 wt.% (BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5 and Co3O4.
The composition of the present invention is not a mere admixture but a synergistic mixture having properties which are different from the mere aggregated properties of the individual ingredients.
The following examples illustrate the invention and the manner in which it may be carried out in practice; however, this should not be construed to limit the scope of the present invention.
Example 1. A batch composition containing 23.09 g BaTiO3 0.27 g Nb205,
0.08 g Li2C204, 0.17 g H3B03 , 0 . 04 g NiO and 0.03 g Mn02 was prepared by mixing the aforesaid powders with 16 g of distilled water in a ball mill (agate grinding medium) for 15 h. The mixed slurry was dried at 150°C in an oven for 4h. The dried mixture was calcined at 600°C for 10 h followed by dry grinding in a ball mill for 6 h to get the capacitor composition (mixed powder).
For testing, pellets of mixed powder (10 mm dia and 2-3 mm thickness) were made by uniaxial pressing (pressure 50 MPa) using

We Claim:
1. A process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability comprising:
a) adding 0.3 - 2.0 wt.% of barium titanate ( BaTi03) fluxes containing Li2C2O4,
Li2B4O7, H3BO3 and Bi2O3 and Bi2O3 to BaTiO3 powder
b) adding 0.75 - 2.0 wt.% (BaTiOs) grain growth inhibitors and Curie peak
suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12 to BaTio3 powder
c) adding 0.03- 0.2 wt.% (of BaTiO3) acceptor dopants containing MnO2, NiO,
CuO, V2O5, and CO3O4 to BaTiO3 powder;
d) mixing the compositions in a ball mill ( agate grinding medium) with 60 - 80,
wt% ( of powder mix) % and distilled water for 10 - 20 h;
e) drying the mixture at 100-150°C in an oven for 2 - 4 h;
f) calcining the mixture at 600-800°C for 5-10 h ;
g) dry grinding of the calcined powder in a ball mill (agate grinding media) for 5-10
h. to obtain the said composition.

2. A process as claimed in claim 1, wherein the flux used is of laboratory reagent grade
and consist of 0 -0.8 wt. % Li2C2O4, 0.3-2.0 wt% Li2B4O7, 0.5-2.0 wt % H3BO3 and
0-0.6 wt% Bi2O3 ( of barium titanate).
3. A process as claimed in claim 1 , wherein the grain growth inhibitor and curie peak
suppressor used are of laboratory reagent grade and consists of 0.5 -0 1..5 wt.%
Nb2O5, 0-1.0 wt. % Bi2 (SnO3)3 and 0-1.0 wt.% Bi4Ti3O12 ( of barium titanate).
4. A process as claimed in claim 1 , wherein the acceptor dopant is of laboratory
reagent grade and consists of 0.01 - 0.15.
5. A process as claimed in claim 1 , wherein the composition so obtained comprises:
i) barium titanate (BaTiO3);
ii) 0.3 - 2.0 wt.% (of BaTiO3) flux containing Li2C2O4. Li2B4O7. H3BO3 and Bi2O3;

iii) 0.75 - 2.0 wt.% of (BaTiO3) grain growth inhibitors and Curie peak suppressors containing Nb2O5, Bi2 (SnO3)3 and Bi4Ti3O12',
iv) 0.03 - 0.2 wt.% (BaTiO3) acceptor dopants containing MnO2, NiO, CuO, V2O5 and Co3O4.
6. A process for preparation of a barium titanate based composition having medium dielectric constant and temperature stability substantially as herein described with reference to the examples accompanying the specification.

Documents:

749-del-1998-abstract.pdf

749-del-1998-claims.pdf

749-del-1998-correspondence-others.pdf

749-del-1998-correspondence-po.pdf

749-del-1998-description (complete).pdf

749-del-1998-form-1.pdf

749-del-1998-form-19.pdf

749-del-1998-form-2.pdf

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Patent Number

218107

Indian Patent Application Number

749/DEL/1998

PG Journal Number

22/2008

Publication Date

30-May-2008

Grant Date

31-Mar-2008

Date of Filing

24-Mar-1998

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	ABHIJIT DAS SHARMA	CGCRI, INDIA.
2	NIHARENDU HALDER	CGCRI, INDIA.
3	SANTA KUMAR KHAN	CGCRI, INDIA.
4	AMARNATH SEN	CGCRI, INDIA.
5	HIMADRI SEKHAR MAITI	CGCRI, INDIA.

PCT International Classification Number

H 01G 4/018

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA