AC & DC Electrical Characterization of PTC <TEX>$BaTiO_3$</TEX> and Electrodes

,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 28(2); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(2): 101.

PTC $BaTiO_3$ 및 전극의 직류 및 교류 특성

전표용, 최경만

포항공과대학교 재료금속공학과

AC & DC Electrical Characterization of PTC $BaTiO_3$ and Electrodes

ABSTRACT

0.2 mo1% La doped BaTiO3 samples were prepared by a wet chemical process (Pechini process) and electrical conductivity were measured from annealing temperatures(800-110$0^{circ}C$) to room temperature continuously. 2 probe I-V characteristics showed that Pt electrodes were non-ohmic below about 80$0^{circ}C$ for Ladoped sample. I-V curves showed varistor behavior and breakdown voltages showed PTC-like behavior. AC complex impedance of 0.2 La and 0.05 Mn mo1% doped BaTiO3 samples with three different electrodes (electroless Ni, Pt, Ag electrodes) were measured with temperature variation. Complex impedance plots showed that the samples with electroless Ni electrodes have negligible electrode resistance. Samples with Ag or Pt paste electrodes showed large electrode resistance. PTC effect, which is defined as the ratio of maximum resistance to minimum resistance, was found to be less than 10 for 0.2 mo1% La doped dense sample however greater than 105 with codoping of 0.05 mo1% Mn and 0.2 mol% La.