Kabushiki Kaisha Toshiba

Yasunori Kasuga

Hideyasu Ando

Toshiya Imai

Takeshi Udagawa

Ando Hideyasu

A current-voltage non-linear resistor () comprises a sintered body () of a mixture whose chief constituent is zinc oxide and including as auxiliary constituents at least bismuth (Bi), antimony (Sb), manganese (Mn), cobalt (Co) and nickel (Ni). Also, the average grain size of the mixture is no more than 0.4 &#x3bc;m; and the average grain size of the zinc oxide grains in the sintered body () is no more than 7.5 &#x3bc;m and the standard deviation based on the grain size distribution of zinc oxide grains in the sintered body () is no more than 15% of the average grain size of the zinc oxide grains.

Current-voltage non-linear resistor and method of manufacture thereof

A ZnO varistor powder can be obtained with high operating voltage and excellent current-voltage nonlinear resistance characteristics. In the ZnO varistor powder, the main ingredient is zinc oxide (ZnO); and at least bismuth (Bi), cobalt (Co), manganese (Mn), antimony (Sb), nickel (Ni), and aluminum (Al), calculated as BiO, COO, MnO, SbO, NiO, and Al, are contained as accessory ingredients in amounts of 0.3 to 1.5 mol % BiO, 0.3 to 2.0 mol % CoO, 0.3 to 3 mol % MnO, 0.5 to 4 mol % SbO, 0.5 to 4 mol % NiO, and 0.0005 to 0.02 mol % Al. ZnO content is greater than or equal to 90 mol %; the bulk density is greater than or equal to 2.5 g/cc; the powder is a spherical powder in which the 50% particle diameter in the particle size distribution is 20 &#x3bc;m to 120 &#x3bc;m.

ZnO varistor powder

A voltage nonlinear resistor has a voltage nonlinear resistive body including zinc oxide, and a side face high-resistance layer provided on the side face of the resistive body. The high-resistance layer contains zinc in an amount of 1.0 to 25% by weigh in terms of its oxide (ZnO), boron in an amount of 1.0 to 10% by weight in terms of its oxide (B O ), silicon in an amount of 0.1 to 5% by weight in terms of its oxide (SiO ), aluminum in an amount of 0.05 to 3% by weight in terms of its oxide (Al O ), and barium in an amount of 0.05 to 3% by weight in terms of its oxide (BaO), with bismuth being substantially the balance in terms of its oxide (Bi O ).

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Tokyo, Japan

Yasunori Kasuga