EP0044981A2
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EP
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Semiconductive ceramic compositions with a nonlinear volt-ampere characteristic, and process for preparing coherent bodies of such compositions
Assignee: Taiyo Yuden Co Ltd
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Filing: 1981-07-07
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Granted: —
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Expires: 2001-07-07
Abstract
Abstract Ceramic materials suitable for use in varistors, enabling the same to function both as such and as capacitors. The ceramic compositions comprise a major proportion of SrTiO 3 , the balance being (1) one or more of Nb 2 O 5 , Ta 2 O 5 , W0 3 , La 2 O 3 , CeO 2 , Nd 2 0 3 , Pr 6 O 11 , Dy 2 0 3 , Y 2 O 3 , and Sm 2 0 3 , for making the compositions semiconductive, and (2) one or more of V 2 O 5 , Cr 2 O 3 , CuO, Cu 2 O, MoO 3 , and MnO 2 , for improving the nonlinear volt-ampere characteristic of the compositions. If desired, for improving the coherency of bodies molded from the composition, there can be added one or more of GeO 2 , ZnO, B 2 0 3 , and PbO. For use as varistors the mixture of the above ingredients, all in finely divided form and made coherent with a binder, is molded into desired shape under pressure. The moldings are first fired in a nonoxidative atmosphere and then further heated in an oxidative atmosphere. Electrodes can be formed as by silver painting.
Inventors
- 👤 Yamaoka Nobutatsu
- 👤 Tsukada Akira
- 👤 Sasazawa Kazuo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 10:49
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/47; H; H01; H01C; H01C7/00; H01C7/10; H01C7/105; H01C7/108; H01C7/115
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
145 words
A semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for varistors, consisting essentially ot: (a) from about 90.000 to about 99.989% SrTiO 3 ; (b) from about 0.001 to about 5.000% of at least one metal oxide, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 0 5 , WO 3 , La 2 O 3 , CeO 2 , Nd203, Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; and (c) from about 0.010 to about 5.000% of at least one other metal oxide, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu 2 O, MoO 3 , and MnO 2 .
Claim 2
Dependent Claim
145 words
A semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for varistors, consisting essentially ot: (a) from about 90.000 to about 99.989% SrTiO 3 ; (b) from about 0.001 to about 5.000% of at least one metal oxide, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 0 5 , WO 3 , La 2 O 3 , CeO 2 , Nd203, Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; and (c) from about 0.010 to about 5.000% of at least one other metal oxide, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu 2 O, MoO 3 , and MnO 2 .
Claim 3
Dependent Claim
191 words
A semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for varistors, consisting essentially of: (a) from about 86.000 to about 99.979% SrTi0 3 ; (b) from about 0.001 to about 5.000% of at least one metal oxide, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , WO 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; (c) from about 0.010 to about 5.000% of at least one other metal oxide, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu 2 0, MoO 3 , and MnO 2 ; and (d) from about 0.010 to about 4.000% of at least one still other metal oxide, for improving the coherency of bodies molded from the composition, selected from the group consisting of GeO 2 , ZnO, B 2 O 3 , and PbO.
Claim 4
Dependent Claim
191 words
A semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for varistors, consisting essentially of: (a) from about 86.000 to about 99.979% SrTi0 3 ; (b) from about 0.001 to about 5.000% of at least one metal oxide, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , WO 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; (c) from about 0.010 to about 5.000% of at least one other metal oxide, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu 2 0, MoO 3 , and MnO 2 ; and (d) from about 0.010 to about 4.000% of at least one still other metal oxide, for improving the coherency of bodies molded from the composition, selected from the group consisting of GeO 2 , ZnO, B 2 O 3 , and PbO.
Claim 5
Dependent Claim
227 words
A process for the fabrication of coherent bonded bodies of a semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for use in varistors, which comprises: . (a) providing a mixture of: (1) from about 90.000 to about 99.989% SrTi0 3 in finely divided form; (2) from about 0.001 to about 5.000% of at least one metal oxide in finely divided form, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , XO 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm203; (3) from about 0.010 to about 5.000% of at least one other metal oxide in finely divided form, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu20, MoO 3 , and MnO 2 ; and (4) a binder; (b) molding the mixture into bodies of desired shape under pressure; (c) firing the bodies in a temperature range of from about 1300 to about 1500° C in a nonoxidative atmosphere; and (d) heating the fired bodies in a temperature range of from about 800 to about 1300° C in an oxidative atmosphere.
Claim 6
Dependent Claim
227 words
A process for the fabrication of coherent bonded bodies of a semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for use in varistors, which comprises: . (a) providing a mixture of: (1) from about 90.000 to about 99.989% SrTi0 3 in finely divided form; (2) from about 0.001 to about 5.000% of at least one metal oxide in finely divided form, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , XO 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm203; (3) from about 0.010 to about 5.000% of at least one other metal oxide in finely divided form, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu20, MoO 3 , and MnO 2 ; and (4) a binder; (b) molding the mixture into bodies of desired shape under pressure; (c) firing the bodies in a temperature range of from about 1300 to about 1500° C in a nonoxidative atmosphere; and (d) heating the fired bodies in a temperature range of from about 800 to about 1300° C in an oxidative atmosphere.
Claim 7
Dependent Claim
274 words
A process for the fabrication of coherent bonded bodies of a semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for use in varistors, which comprises: (a) providing a mixture of: (1) from about 86.000 to about 99.979% SrTi0 3 in finely divided form; (2) from about 0.001 to about 5.000% of at least one metal oxide in finely divided form, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , W0 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; (3) from about 0.010 to about 5.000% of at least one other metal oxide in finely divided form, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu20, Mo03, and MnO 2 ; (4) from about 0.010 to about 4.000% of at least one still other metal oxide in finely divided form, for improving the coherency of the bodies of the composition, selected from the group consisting of Ge0 2 , ZnO, B 2 O 3 , and PbO; and (5) a binder; (b) molding the mixture into bodies of desired shape under pressure; (c) firing the bodies in a temperature range of from about 1300 to about 1500° C in a nonoxidative atmosphere; and (d) heating the fired bodies in a temperature range of from about 900 to about 1300° C in an oxidative atmosphere.
Claim 8
Dependent Claim
274 words
A process for the fabrication of coherent bonded bodies of a semiconductive ceramic composition with a nonlinear volt-ampere characteristic, particularly well suited for use in varistors, which comprises: (a) providing a mixture of: (1) from about 86.000 to about 99.979% SrTi0 3 in finely divided form; (2) from about 0.001 to about 5.000% of at least one metal oxide in finely divided form, for making the composition semiconductive, selected from the group consisting of Nb 2 O 5 , Ta 2 O 5 , W0 3 , La 2 O 3 , CeO 2 , Nd 2 O 3 , Pr 6 O 11 , Dy 2 O 3 , Y 2 O 3 , and Sm 2 O 3 ; (3) from about 0.010 to about 5.000% of at least one other metal oxide in finely divided form, for improving the nonlinear volt-ampere characteristic of the composition, selected from the group consisting of V 2 O 5 , Cr 2 O 3 , CuO, Cu20, Mo03, and MnO 2 ; (4) from about 0.010 to about 4.000% of at least one still other metal oxide in finely divided form, for improving the coherency of the bodies of the composition, selected from the group consisting of Ge0 2 , ZnO, B 2 O 3 , and PbO; and (5) a binder; (b) molding the mixture into bodies of desired shape under pressure; (c) firing the bodies in a temperature range of from about 1300 to about 1500° C in a nonoxidative atmosphere; and (d) heating the fired bodies in a temperature range of from about 900 to about 1300° C in an oxidative atmosphere.
Claim 9
Dependent Claim
26 words
A process according to claims 3 or 4, wherein the mixture is molded at pressures ranging from about 500 to about 2000 kg/ cm 2 .
Claim 10
Dependent Claim
18 words
A process according to claims 3 or 4, wherein the molded bodies are fired in a reductive atmosphere.
Claim 11
Dependent Claim
23 words
A process according to claim 6, wherein the atmosphere is about 95 volume % molecular nitrogen and about five volume % molecular hydrogen.
Claim 12
Dependent Claim
14 words
A process according to claims 3 or 4, wherein the binder is polyvinyl alcohol.
References Cited (Backward Citations)
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