소결시간에 따른 ZPCCD계 바리스터의 전기적 특성 및 안정성

The electrical properties and stability of the varistors composed of ZnO-Pr 6 O 11 -CoO-Cr₂O₃-Dy₂O₃ system were investigated with sintering time in the range of 1~3 h at 1350℃. As the sintering time was increased, the varistor voltage and leakage current increased, but the nonlinear exponent decreased. The varistors sintered for 1 h exhibited excellent nonlinearity, with a nonlinear exponent of 55.3 and a leakage current of 0.1 μA, whereas presented relatively low stability. The varistors sintered for 2 h exhibited not only high nonlinear exponent of 46.3, low leakage current of 0.3 ㎂, low dielectric dissipation factor of 0.0431, but also the highest stability, in which the variation rates of varistor voltage, nonlinear exponent, leakage current, dielectric constant, and dielectric dissipation factor were -3.0%, -4.1%, +3056.2%, +5.1%, and -12.5%, respectively, after DC accelerated aging stress state of 0.95 V 1mA /150℃/24 h. On the whole, the nonlinearity and stability of these varistors are greatly affected by the sintering time.