Title of Invention	"A PROCESS FOR THE PREPARATION OF A NOVEL CERAMIC MATERIAL USEFUL FOR MICROWAVE INTEGRATED CIRCUIT APPLICATIONS"
Abstract	Title: A process for the preparation of novel ceramic material having the composition BaCO3, 1n2O3, T\02 useful for microwave integrated circuit applications A process for the preparation of novel ceramic material having the composition In2O3, TiC2 useful for microwave integrated circuit applications which comprises a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide b) grinding the mixture thoroughly to form a uniform reaction mixture c) heating the resultant mixture in a crucible to a temperature range of 1000 to 1200°C d) cooling the reaction mixture e) grinding the resultant product into a powder f) compacting the resultant powder to the desired shapes and sizes and g) sintering the resultant compacts at a temperature in the range of 1225 to 1265°C for a period ranges from 3 to 6 hours.

Title of Invention

"A PROCESS FOR THE PREPARATION OF A NOVEL CERAMIC MATERIAL USEFUL FOR MICROWAVE INTEGRATED CIRCUIT APPLICATIONS"

Abstract

Title: A process for the preparation of novel ceramic material having the composition BaCO3, 1n2O3, T\02 useful for microwave integrated circuit applications A process for the preparation of novel ceramic material having the composition In2O3, TiC2 useful for microwave integrated circuit applications which comprises a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide b) grinding the mixture thoroughly to form a uniform reaction mixture c) heating the resultant mixture in a crucible to a temperature range of 1000 to 1200°C d) cooling the reaction mixture e) grinding the resultant product into a powder f) compacting the resultant powder to the desired shapes and sizes and g) sintering the resultant compacts at a temperature in the range of 1225 to 1265°C for a period ranges from 3 to 6 hours.

Full Text	This invention relates a process for the prepartation of a nove( ceramic material useful for microwave integrated circuit applications. This invention particularly provides a process for the preparation of a novel dielectric ceramic material system Ba-In-Ti-0 having superior characteristics compared to the existing similar ceramics used in C and X bands of microwave communication. This invention more particularly provides a process for the preparation of novel dielectric ceramic resonator system BaO-In203~Ti02 having superior qualities. Communication in the microwave frequency range is now becoming more closer to the individuals. The personal communication in the microwave is rapidly developing and heading towards a situation whereby communication is possible between persons anywhere in the world at any time. With this in mind, industries all around the world are trying for the miniaturisation of complex microwave devices in order to make the system handy and easy-to-use. Dielectric substances, particularly ceramics, have gained the attention of scientists and engineers sine they offer miniaturisation of components. The advantages that ceramics have over other materials are compactness, chemical stability, low cost of production, high efficiency, adaptability to microwave integrated circuits (MIC) . ry- .•:. (D.Kajfez and P. Guillon, Dielectric Resonators, 1986,1 Njorwood, MA, Artech House). Basically a dielectric resonator (DR) confines a few discrete frequencies by virtue of its high relative permittivity. This frequency depends on the size of the resonator ceramic and the dielectric constant (K) of the material. For a given size of the resonator, the resonant frequency depends entirely on the K of the material. In short, a DR sustains an electromagnetic wave of wavelength times its size. In order to have high efficiency, the dielectric loss of the material should be minimum. It is desirable that the resonator possesses a Q value greater than 2,000 at the resonant frequency. Moreover the resonant frequency should be stable with temperature. Hence for a ceramic material to be selected as DR for practical applications, it must possess 1. a high dielectric constant,namely, K >25 2. a high unloaded quality factor, namely, Q >2,000 and 3. small temperature-coefficient of resonant-frequency,namely, Tcf Few resonator ceramic compositions satisfying the above said criteria are being used for microwave integrated circuits applications (J.K. Plourde, D. F. Linn, H. M. O'Bryan Jr. and J.Thomson Jr., J. Am. Ceram. Soc., 58, 418, (1975); K. Waino, K. Minai and H.Tamura, J. Am. Ceram. Soc., 67, 278, (1984)). Recently a few ceramic materials such as Ba2Tig02o(H.M. O'Bryan, J.Thomson, J.K.Plourde, J.Amer. Cer. Society, 57(1974)450); H.Sreemoolanadhan, J. Isaac, P. Koshy, M.T.Sebastian, K.A.Jose and P.Mohanan,Bri. Ceramic Trans. J. 94(1995) 157); Ti02(K.Wakino, K.Minia & H.Tamura, J. Amer. Ceram. Soc. 67(1984)278; H.Sreemoolanadhan, M.T.Sebastian & P.Mohanan, Bri. Ceramic Trans. J. 95(1996)In Press); (Zr,Sn)Ti04(G.Wolfram and H.E.Goebel, Mater. Res. Bull. 30(1995) 653) have been investigated. However, there is possibility of developing new materials with better characteristics that the existing ones can be replaced. Microwave dielectric resonators are extensively used in the communication industry for Cellular Telephones, Satellite broadcasting system etc. for generation and selection of carrier frequencies. Because of high dielectric constant, loss loss and high temperature-stability, DRs have become indispensable components in all sorts of MIC applications. DRs offer small size, light weight, high efficiency and low cost compared to Copper and Invar cavity resonators. Consequently, extensive search for new ceramics with better characteristics for industrial applications is progressing around the world. Presently available ceramics with K in the range 30 to 40 have reported quality factors (Q) grater than 6, 000 at 7 GHz. Hence the search for new ceramic materials for resonator applications are given top priority in electroceramics. The main objective of the present invention is to provide a process for the preparation of a new ceramic material based on Ba-In-Ti-O system. Another objective of the present invention is to provide a process for the preparation of a ceramic material having BaO-In203-Ti02 which is useful for microwave integrated circuit applications. According to the present invention, there is provided a process for the preparation of novel ceramic material having the composition BaCOs, In203, Ti02 useful for microwave integrated circuit applications which comprises a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide at a ratio 1:1:5, b) grinding the mixture thoroughly to form a uniform reaction mixture c) heating the resultant mixture in a crucible to a temperature range of 1000 to 1200°C d) cooling the reaction mixture e) grinding the resultant product into a powder f) compacting the resultant powder to the desired shapes and sizes and a) sintering the resultant compacts at a temperature in the range of 1225 to 1265°C for a period ranges from 3 to 6 hours.. The reaction of the process of the invention is given below BaCOs + In203 + Ti02 > BaIn2Ti5Oi4 + Co2 Starting materials used were 99.9% pure. The stoichiometric quantities of the starting materials may be used and the mixturemay be heated to a temperature range from 1000 to 1200 °C. The calcined powder was throughly ground and if desired pressed into compacts of different sizes to suit the requirement. These compacts were sintered at about 1250 °C for 4 hours. The details of the present invention is given in the Examples which are provided by way of illustration and therefore should not be constraint to limit the scope of the present investigation . Example 1:- 1.97341 gms of BaCC>3, 3.995 gms of Ti(>2 and 2.7764 gms of In203 are weighed and mixed well and ground well in agate mortar for 1 hour. It is then taken in platinum crucible and heated at 1200 C for 4 hours. The powder sample is then cooled to room temperature. The sample is then ground well in an agate for 2 hours. It is then mixed with 3 ml of binder Poly Vinyl Alcohol (PVA) and is again mixed well. The mixture is then shaped into cylindrical pellets of 10 mm diameter and 7mm height. The cylindrical pellets are then kept on a platinum plate and sintered at 1250°C for 4 hours. The samples are then cooled to room temperature . Example 2:- 2.960115 gms of BaCO3, 5.9925 gms of TiO£ and 4.1646 gms of In203 are weighed, mixed and ground well in agate for 2 hours. It is then taken in a platinum crucible and heated at 1150°C for 6 hours. The powder sample is then cooled to room temperature. The sample is then ground well in an agate for 3 hours. It is then mixed with 4ml of binder PVA and is again mixed well. The mixture is then shaped into cylindrical pellets of llmm diameter and 8 mm height. The cylindrical pellets are then kept on a platinum plate and sintered at 1255°C for 3 hours. The sample is then cooled to room temperature. The powder X-ray diffraction pattern of the ceramic material prepared, using CuKa radiation is shown in Fig.l of the drawing accompanying the system. The pattern shows that the material is • monophase in constitution. The symmetry of the unit cell is orthorhombic with perovskite-like arrangement of ions. The XRD data of this new compound is compared with that of similar compounds data are compared and the peak positions match with them within the limits of tolerance. This BIT cermaic resonaTOR showed a sharp TE011 mode resonance at 5.54 GHz. The K of the material was calculated from the frequency of TEon resonance using a known technique (B. W. Hakki and P. D. Coleman, IRE Trans. Microwave Theory Tech., MTT-8, 402 (I960)). This resonator was then coupled to a 50 ohm microstripline enclosed in a brass enclosure and the transmission curve was taken for Q determination (A. P. S. Khanna and Y. Garault, IEEE Trans. Microwave Theory Tech, MTT-31, 261, (1983)). Of the various cut-off narrow bands, the one at 7.29 GHz showed the least transmission coefficient equal to 57 m Units. The resonant curve had a width of 980 kHz giving a Q factor of 7,400. The TE0ii mode of the resonator under the end-shorted condition showed a decrease of 0.82 MHz over the temperature range 25-75 °C. The temperature-coefficient of resonant-frequency (Tcf) calculated is -2 ppmK-1 . The density of the resonator was 4.9 g/cm . The new ceramic material prepared has superior characteristics in comparison to existing ceramics like temperature stability of resonant frequency. The BIT material prepared by the process of the present invention has a low processing temperatures compared to the currently availabe compositions. About 100 C difference in sintering temperature saves considerable energy and thus the expense of manufacturing. Also, the density—factor for weight-is lower compared to one of the presently used materials. The table shown below compares the properties and advantages of BIT ceramic over two commonly used DR compositions in the C and X bands — (Zr, Sn)TiC4 and (Zr,Sn)Ti04 (Table Removed) Advantages of the invention (1) The ceramic material having composition BaIn2Ti5 v2) the new ceramic material is lighter than the extensively used (Zr, Sn)Ti04 (3) the new ceramic material has high dielectric constant (K > 30) comparable to that of the existing resonator materials. (4) the new ceramic material has a high quality factor (Q > 7, 000) at 7.3 GHz that is superior to the existing resonator materials used in the C and X bands of microwave frequency range. (5) the new ceramic has a small temperature coefficient of resonant frequency (Tcf compositional adjustments. (6) the processing temperature of the new ceramic material is remarkably low (1200 to 1265° ) compared to the existing resonator materials(1350 to 1400°C) used in the C and X bands of microwave frequency range there by reducing the production cost. It is evident from the aforesaid factors that the ceramic material has the composition BaIn2Ti5Oi5O14, prepared by the process of the present invention has superior qualities and can therefore replace the existing resonators in the C and X bands. We Claim: 1. A process for the preparation of novel ceramic material having the composition BaCO3, In2O3, T\02 useful for microwave integrated circuit applications which comprises a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide at a ratio 1:1:5, b) grinding the mixture thoroughly to form a uniform reaction mixture c) heating the resultant mixture in a crucible to a temperature range of 1000 to!200°C d) cooling the reaction mixture e) grinding the resultant product into a powder f) compacting the resultant powder to the desired shapes and sizes and g) sintering the resultant compacts at a temperature in the range of 1225 to 1265°C for a period ranges from 3 to 6 hours. 2. A process as claimed in claim 1 wherein stoichiometric quantities of the starting materials are used. 3. A process as claimed in claims 1 wherein the compacts formed are sintered at a temperature of 1250°C for 4 hours. 4. A process for the preparation of novel ceramic material having the composition BaCO3, In203, TiO2 useful for microwave integrated circuit applications substantially as herein described with reference to the Examples.

Full Text

This invention relates a process for the prepartation of a nove( ceramic material useful for microwave integrated circuit applications. This invention particularly provides a process for the preparation of a novel dielectric ceramic material system Ba-In-Ti-0 having superior characteristics compared to the existing similar ceramics used in C and X bands of microwave communication. This invention more particularly provides a process for the preparation of novel dielectric ceramic resonator system BaO-In203~Ti02 having superior qualities.
Communication in the microwave frequency range is now becoming more closer to the individuals. The personal communication in the microwave is rapidly developing and heading towards a situation whereby communication is possible between persons anywhere in the world at any time. With this in mind, industries all around the world are trying for the miniaturisation of complex microwave devices in order to make the system handy and easy-to-use.
Dielectric substances, particularly ceramics, have gained the attention of scientists and engineers sine they offer miniaturisation of components. The advantages that ceramics have over other materials are compactness, chemical stability, low cost of production, high efficiency, adaptability to microwave integrated circuits (MIC) . ry- .•:. (D.Kajfez and P. Guillon, Dielectric Resonators, 1986,1 Njorwood, MA, Artech House).
Basically a dielectric resonator (DR) confines a few discrete frequencies by virtue of its high relative permittivity. This frequency depends on the size of the resonator ceramic and the dielectric constant (K) of the material. For a given size of the resonator, the resonant frequency depends entirely on the K of the material. In short, a DR sustains an electromagnetic wave of wavelength times its size. In order to have high efficiency, the dielectric loss of the material should be minimum. It is desirable that the resonator possesses a Q value greater than 2,000 at the resonant frequency. Moreover the resonant frequency should be stable with temperature.
Hence for a ceramic material to be selected as DR for practical applications, it must possess
1. a high dielectric constant,namely, K >25
2. a high unloaded quality factor, namely, Q >2,000 and
3. small temperature-coefficient of resonant-frequency,namely,
Tcf Few resonator ceramic compositions satisfying the above said criteria are being used for microwave integrated circuits applications (J.K. Plourde, D. F. Linn, H. M. O'Bryan Jr. and J.Thomson Jr., J. Am. Ceram. Soc., 58, 418, (1975); K. Waino, K. Minai and H.Tamura, J. Am. Ceram. Soc., 67, 278, (1984)). Recently a few ceramic materials such as Ba2Tig02o(H.M. O'Bryan, J.Thomson, J.K.Plourde, J.Amer. Cer. Society, 57(1974)450); H.Sreemoolanadhan, J. Isaac, P. Koshy, M.T.Sebastian, K.A.Jose and P.Mohanan,Bri. Ceramic Trans. J. 94(1995) 157);
Ti02(K.Wakino, K.Minia & H.Tamura, J. Amer. Ceram. Soc. 67(1984)278; H.Sreemoolanadhan, M.T.Sebastian & P.Mohanan, Bri. Ceramic Trans. J. 95(1996)In Press); (Zr,Sn)Ti04(G.Wolfram and H.E.Goebel, Mater. Res. Bull. 30(1995) 653) have been investigated. However, there is possibility of developing new materials with better characteristics that the existing ones can be replaced.
Microwave dielectric resonators are extensively used in the communication industry for Cellular Telephones, Satellite broadcasting system etc. for generation and selection of carrier frequencies. Because of high dielectric constant, loss loss and high temperature-stability, DRs have become indispensable components in all sorts of MIC applications. DRs offer small size, light weight, high efficiency and low cost compared to Copper and Invar cavity resonators.
Consequently, extensive search for new ceramics with better characteristics for industrial applications is progressing around the world. Presently available ceramics with K in the range 30 to 40 have reported quality factors (Q) grater than 6, 000 at 7 GHz. Hence the search for new ceramic materials for resonator
applications are given top priority in electroceramics.
The main objective of the present invention is to provide a process for the preparation of a new ceramic material based on Ba-In-Ti-O system. Another objective of the present invention is to provide a process for the preparation of a ceramic material
having BaO-In203-Ti02 which is useful for microwave integrated circuit applications.
According to the present invention, there is provided a process for the preparation of novel ceramic material having the composition BaCOs, In203, Ti02 useful for microwave integrated circuit applications which comprises
a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide at a
ratio 1:1:5,
b) grinding the mixture thoroughly to form a uniform reaction mixture
c) heating the resultant mixture in a crucible to a temperature range of 1000
to 1200°C
d) cooling the reaction mixture
e) grinding the resultant product into a powder
f) compacting the resultant powder to the desired shapes and sizes and
a) sintering the resultant compacts at a temperature in the range of 1225 to 1265°C for a period ranges from 3 to 6 hours..
The reaction of the process of the invention is given below BaCOs + In203 + Ti02
> BaIn2Ti5Oi4 + Co2
Starting materials used were 99.9% pure. The stoichiometric quantities of the starting materials may be used and the mixturemay be heated to a temperature range from 1000 to 1200 °C. The calcined powder was throughly ground and if desired pressed into compacts of different sizes to suit the requirement. These compacts were sintered at about 1250 °C for 4 hours.
The details of the present invention is given in the Examples which are provided by way of illustration and therefore should not be constraint to limit the scope of the present investigation .
Example 1:- 1.97341 gms of BaCC>3, 3.995 gms of Ti(>2 and 2.7764 gms of In203 are weighed and mixed well and ground well in agate mortar for 1 hour. It is then taken in platinum crucible and heated at 1200 C for 4 hours. The powder sample is then cooled to room temperature. The sample is then ground well in an agate for 2 hours. It is then mixed with 3 ml of binder Poly Vinyl Alcohol (PVA) and is again mixed well. The mixture is then shaped into cylindrical pellets of 10 mm diameter and 7mm height. The cylindrical pellets are then kept on a platinum plate and sintered at 1250°C for 4 hours. The samples are then cooled to room temperature .
Example 2:- 2.960115 gms of BaCO3, 5.9925 gms of TiO£ and 4.1646 gms of In203 are weighed, mixed and ground well in agate for 2
hours. It is then taken in a platinum crucible and heated at 1150°C for 6 hours. The powder sample is then cooled to room temperature. The sample is then ground well in an agate for 3 hours. It is then mixed with 4ml of binder PVA and is again mixed
well. The mixture is then shaped into cylindrical pellets of llmm
diameter and 8 mm height. The cylindrical pellets are then kept
on a platinum plate and sintered at 1255°C for 3 hours. The
sample is then cooled to room temperature.
The powder X-ray diffraction pattern of the ceramic material prepared, using CuKa radiation is shown in Fig.l of the drawing accompanying the system. The pattern shows that the material is
•
monophase in constitution. The symmetry of the unit cell is orthorhombic with perovskite-like arrangement of ions. The XRD data of this new compound is compared with that of similar compounds data are compared and the peak positions match with them within the limits of tolerance.
This BIT cermaic resonaTOR showed a sharp TE011 mode resonance at 5.54 GHz. The K of the material was calculated from the frequency of TEon resonance using a known technique (B. W. Hakki and P. D. Coleman, IRE Trans. Microwave Theory Tech., MTT-8, 402 (I960)). This resonator was then coupled to a 50 ohm microstripline enclosed in a brass enclosure and the transmission curve was taken for Q determination (A. P. S. Khanna and Y. Garault, IEEE Trans. Microwave Theory Tech, MTT-31, 261, (1983)). Of the various cut-off narrow bands, the one at 7.29 GHz showed the least transmission coefficient equal to 57 m Units. The resonant curve had a width of 980 kHz giving a Q factor of 7,400. The TE0ii mode of the resonator under the end-shorted condition showed a decrease of 0.82 MHz over the temperature range 25-75 °C. The temperature-coefficient of resonant-frequency (Tcf)
calculated is -2 ppmK-1 . The density of the resonator was 4.9
g/cm .
The new ceramic material prepared has superior characteristics in comparison to existing ceramics like temperature stability of resonant frequency. The BIT material prepared by the process of the present invention has a low processing temperatures compared to the currently availabe compositions. About 100 C difference in sintering temperature saves considerable energy and thus the expense of manufacturing. Also, the density—factor for weight-is lower compared to one of the presently used materials.
The table shown below compares the properties and advantages of BIT ceramic over two commonly used DR compositions in the C and X bands — (Zr, Sn)TiC4 and
(Zr,Sn)Ti04

(Table Removed)
Advantages of the invention
(1) The ceramic material having composition BaIn2Ti5 v2) the new ceramic material is lighter than the extensively used (Zr, Sn)Ti04
(3) the new ceramic material has high dielectric constant (K >
30) comparable to that of the existing resonator materials.
(4) the new ceramic material has a high quality factor (Q > 7,
000) at 7.3 GHz that is superior to the existing resonator
materials used in the C and X bands of microwave frequency range.
(5) the new ceramic has a small temperature coefficient of
resonant frequency (Tcf compositional adjustments.
(6) the processing temperature of the new ceramic material is
remarkably low (1200 to 1265° ) compared to the existing
resonator materials(1350 to 1400°C) used in the C and X bands of
microwave frequency range there by reducing the production cost.
It is evident from the aforesaid factors that the ceramic material has the composition BaIn2Ti5Oi5O14, prepared by the process of the present invention has superior qualities and can therefore replace the existing resonators in the C and X bands.

We Claim:
1. A process for the preparation of novel ceramic material having the composition BaCO3, In2O3, T\02 useful for microwave integrated circuit applications which comprises
a) mixing oxides or carbonates of Barium, Indium and Titanium dioxide at a
ratio 1:1:5,
b) grinding the mixture thoroughly to form a uniform reaction mixture
c) heating the resultant mixture in a crucible to a temperature range of 1000
to!200°C
d) cooling the reaction mixture
e) grinding the resultant product into a powder
f) compacting the resultant powder to the desired shapes and sizes and
g) sintering the resultant compacts at a temperature in the range of 1225 to
1265°C for a period ranges from 3 to 6 hours.

2. A process as claimed in claim 1 wherein stoichiometric quantities of the
starting materials are used.
3. A process as claimed in claims 1 wherein the compacts formed are sintered
at a temperature of 1250°C for 4 hours.
4. A process for the preparation of novel ceramic material having the
composition BaCO3, In203, TiO2 useful for microwave integrated circuit
applications substantially as herein described with reference to the Examples.

Documents:

1535-del-1996-abstract.pdf

1535-del-1996-claims.pdf

1535-del-1996-correspondence-others 1..pdf

1535-del-1996-correspondence-others.pdf

1535-del-1996-correspondence-po.pdf

1535-del-1996-description (complete).pdf

1535-del-1996-form-1.pdf

1535-del-1996-form-3.pdf

1535-del-1996-form-4.pdf

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Patent Number

213822

Indian Patent Application Number

1535/DEL/1996

PG Journal Number

04/2008

Publication Date

25-Jan-2008

Grant Date

17-Jan-2008

Date of Filing

11-Jul-1996

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	HARIHARA IYER SREEMOOLANATHAN	RRL, TRIVANDRUM AND PEZHOLIL MOHANAN, DEPARTMENT OF ELECTRONIC, COCHIN UNIVERSITY OF SCIENCE & TECHNOLOGY.
2	RAVEENDRAN RATHEESH MAILADIL THOMAS SEBASTAIN	RRL, TRIVANDRUM AND PEZHOLIL MOHANAN, DEPARTMENT OF ELECTRONIC, COCHIN UNIVERSITY OF SCIENCE & TECHNOLOGY.

PCT International Classification Number

C08L 1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA