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Composite material for positive temperature coefficient thermistor, ceramic for positive temperature coefficient thermistor and method for manufacturing ceramics for positive temperature coefficient thermistor

  • US 6,346,496 B2
  • Filed: 07/23/1999
  • Issued: 02/12/2002
  • Est. Priority Date: 07/24/1998
  • Status: Expired due to Term
First Claim
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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.

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