Composite material for positive temperature coefficient thermistor, ceramic for positive temperature coefficient thermistor and method for manufacturing ceramics for positive temperature coefficient thermistor
First Claim
1. A method for manufacturing the ceramic for use in a PTC thermistor comprising providing a BaTiO3-containing composite material containing a semiconducting additive, firing the composite material in a neutral or reducing atmosphere and then heat-treating the fired material in an oxidative atmosphere, wherein the composite material comprises a principal component containing about 30 to 97 mol % of BaTiO3;
- about 1 to 50 mol % of PbTiO3;
about 1 to 30 mol % of SrTiO3; and
about 1 to 25 mol % of CaTiO3, wherein the total content of BaTiO3 PbTiO3 SrTiO3 and CaTiO3 is 100 mol %; and
relative to 100 moles of the principal component, as additives, about 0.1 to 0.3 moles of Sm as Sm in a compound containing Sm;
about 0.01 to 0.03 moles of Mn as Mn in a compound containing Mn; and
0 to about 2.0 moles of Si as Si in a compound containing Si.
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Accused Products
Abstract
A ceramic for the PTC thermistor having a resistivity at room temperature of 5 Ω·cm or less, static withstanding voltage of 60 V/mm or more and temperature resistance coefficient of 9.0 %/° C., having small dispersion of the resistance, is composed of principal components of about 30 to 97 mol % of BaTiO3, about 1 to 50 mol % of PbTiO3, about 1 to 30 mol % of SrTiO3 and about 1 to 25 mol % of CaTiO3 (the total content of them being 100 mol %), as well as about 0.1 to 0.3 mole of Sm, about 0.01 to 0.03 mole of Mn and 0 to about 2.0 mole of Si relative to 100 moles of the principal components, the composite material being preferably heat-treated in an oxidative atmosphere after being fired in a reducing or neutral atmosphere for obtaining the ceramic.
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Citations
10 Claims
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1. A method for manufacturing the ceramic for use in a PTC thermistor comprising providing a BaTiO3-containing composite material containing a semiconducting additive, firing the composite material in a neutral or reducing atmosphere and then heat-treating the fired material in an oxidative atmosphere, wherein the composite material comprises a principal component containing about 30 to 97 mol % of BaTiO3;
- about 1 to 50 mol % of PbTiO3;
about 1 to 30 mol % of SrTiO3; and
about 1 to 25 mol % of CaTiO3, wherein the total content of BaTiO3 PbTiO3 SrTiO3 and CaTiO3 is 100 mol %; and
relative to 100 moles of the principal component, as additives, about 0.1 to 0.3 moles of Sm as Sm in a compound containing Sm;
about 0.01 to 0.03 moles of Mn as Mn in a compound containing Mn; and
0 to about 2.0 moles of Si as Si in a compound containing Si. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- about 1 to 50 mol % of PbTiO3;
Specification
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- Resources
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Current AssigneeMurata Manufacturing Co Limited
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Original AssigneeMurata Manufacturing Co Limited
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InventorsYamamoto, Noriyuki, Okamoto, Tetsukazu, Hirota, Toshiharu, Nabika, Yasuhiro
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Primary Examiner(s)Group, Karl
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Application NumberUS09/360,313Publication NumberTime in Patent Office935 DaysField of Search338/22.R, 338/225.D, 252/520.21, 252/520.22, 501/137, 501/138, 501/139, 264/617, 264/676US Class Current501/137CPC Class CodesH01C 17/30 adapted for bakingH01C 7/025 Perovskites, e.g. titanates
