Abstract: Provided is a semiconductor ceramic and a semiconductor ceramic element each having a room temperature specific resistance of 3 &OHgr;·cm or lower and a resistance temperature characteristic of 9%/° C. or more. The semiconductor ceramic is characterized in that the ratio R1/(R1+R2), in which R1 is the transgranular resistance value of the crystal particles and R2 is the intergranular resistance value of the crystal particles and R1+R2 is the overall resistance value representing the sum of R1 and R2, is about 0.35 to 0.85.

Abstract: A semiconductor ceramic device comprises a body composed of a semiconductor ceramic having a positive resistance-temperature coefficient primarily composed of barium titanate and electrodes provided on the body, in which the resistance-temperature coefficient is 9%/° C. or more, resistivity is 3.5 ∩·cm or less, and withstand voltage is 50 V/mm or more. As the semiconductor ceramic forming the body provided in a thermistor having positive resistance-temperature characteristics, a semiconductor ceramic having a positive resistance-temperature coefficient is used, in which the semiconductor ceramic has an average particle diameter of about 7 to 12 &mgr;m and comprises barium titanate as a major component and sodium in an amount of about 70 ppm or less on a weight basis.

Abstract: A semiconductor ceramic composed of barium titanate, lead titanate, strontium titanate, and calcium titanate as primary components, includes samarium oxide as a semiconductor-forming agent in the primary components, and the average diameter of crystalline particles of the semiconductor ceramic is about 7 to 12 &mgr;m. The semiconductor ceramic has a resistivity at room temperature not greater than 3.5 &OHgr;cm, a withstand voltage not less than 50 V/mm, a resistance-temperature coefficient &agr;10-100 not less than 9%/°C. and also has less variability of resistance.

Abstract: A ceramic for the PTC thermistor having a resistivity at room temperature of 5 &OHgr;·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.

Abstract: A ceramic for the PTC thermistor having a resistivity at room temperature of 5 &OHgr;·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.