Matsushita Electric Industrial Co., Ltd.

Masanori Fujimura

Tomizo Matsuoka

Yoshihiro Matsuo

Shigeru Hayakawa

Mitsuhiro Yamamoto

Tokuji Nishino

Mitsuaki Kimoto

A ceramic capacitor for operating at a suppressed self heat-generation and a low loss even in high voltage operating conditions, including a dielectric ceramic element assembly having two surfaces and made of a material selected from the group consisting of a dielectric composition of CaTiO &mdash;La O &mdash;TiO system, a dielectric composition of CaTiO &mdash;La O &mdash;TiO &mdash;SrTiO system, a dielectric composition of SrTiO &mdash;CaTiO system, a dielectric composition of SrTiO &mdash;CaTiO &mdash;Bi O &mdash;TiO system, a dielectric composition of SrTiO &mdash;PbTiO &mdash;PbTiO system, and a dielectric composition of SrTiO &mdash;PbTiO &mdash;Bi TiO &mdash;CaTiO system; and an electrode made mainly of Zn located on each of the two surfaces of the dielectric ceramic element.

Ceramic capacitor

A PTC thermistor composition comprising BaTiO.sub.3, TiO.sub.2, one oxide selected from the group consisting of Nb.sub.2 O.sub.5 and Y.sub.2 O.sub.3, Al.sub.2 O.sub.3, SiO.sub.2, Li.sub.2 CO.sub.3, MnO.sub.2 and one oxide selected from the group consisting of Sb.sub.2 O.sub.3 and Bi.sub.2 O.sub.3, and process for the production thereof are provided. Said process is characterized by the addition of TiO.sub.2 and Nb.sub.2 O.sub.5 to BaTiO.sub.3 before calcination and the addition of Al.sub.2 O.sub.3, SiO.sub.2, Li.sub.2 CO.sub.3, MnO.sub.2 and Sb.sub.2 O.sub.3 after the calcination. This PTC thermistor composition has a high breakdown voltage, a large electric current at the initial moment of a voltage application which current decreases rapidly with continuing voltage application, low specific resistivity and, good stability of resistivity.

PTC thermistor composition and method of making the same

A PTC thermistor composition containing barium oxide and titanium oxide as a base material, a semiconducting element to make the base material semiconductive and hafnium dioxide, and if necessary, an additive element. Due to the use of hafnium dioxide, the thermistor composition contributes to a large positive temperature coefficient of resistance. This invention also provides a novel method of making the thermistor composition, in which the addition of hafnium is carried out at the step of milling which comes after the step of calcining. By this method, hafnium can be very effectively used.

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Hirakata, Japan

Masanori Fujimura