Central Glass Company, Limited

Takamitsu Eonomoto

Noboru Murata

Naoki Okada

Hiroshi Ueda

Midori Kawahara

A modified lead barium titanate ceramic which has a fundamental composition of (Ba.sub.1-x-y Sb.sub.y Pb.sub.x)TiO.sub.3, where x is not greater than 0.9 and usually not smaller than 0.6 and y is from 0.001 to 0.1, and has a high positive temperature coefficient of resistivity (PTCR) over a range of temperature higher than about 350.degree. C. at the lower boundary, is produced by using a metal salt of an organic acid such as lead titanate salt of oxalic acid as the source of Pb and by adding at least one of BaCO.sub.3, SiO.sub.2, BN and TiO.sub.2 to the raw materials of the above fundamental composition. After thermally decomposing the organic acid metal salt the mixture of the raw materials including the additive(s) is compacted and sintered. By this method the sintering is achieved with good reproducibility and with little dissipation of lead, and the obtained titanate ceramic is good and durable in the PTCR characteristics and hence is useful as the material of a PTC thermistor functioning at medium-to-high temperatures.

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Ube, Japan

Takamitsu Eonomoto