Sintered varistor material with small particle size

摘要

A varistor material having a non-linear coefficient of at least 30 and a varistor voltage of at least 800 V/mm is disclosed. The varistor is produced by a method including commingling an admixture of ZnO and a manganese compound while preventing the admixture from contacting with a surface containing an element belonging to group IIIb of the Periodic Table. The resulting mixture is calcined and then pulverized while preventing the contact with a IIIb element-containing surface to obtain a pulverized product having a content of impurity compounds of a IIIb element of not greater than 20 ppm by weight. The pulverized product is molded and sintered at such a temperature as to obtain the varistor formed from particles with an average particle size of not greater than 5 mu m.