Fabrication and properties of multilayer Sr0.7Ba0.3TiO3 ceramic varistors

The fabrication and properties of the multilayer Sr_0.7Ba_0.3TiO₃ ceramic varistors made from low-fire Sr_0.7Ba_0.3TiO₃-based ceramic materials doped with small amounts of additives such as Nb₂O₅ and Li₂CO₃ are described. After being sintered at 1100° C in a reducing atmosphere and annealed at 900° C in air, the varistors exhibited the following characteristics: varistor voltage V_1mA, 10 v; nonlinear coefficientα, 15. The varistor voltage was almost unchanged against a supplied surge energy of 300 J/cm³. The varistors had excellent capacitor characteristics. The capacitance and loss factor were 80 nF and 2%, respectively.