TIME-DEPENDENT CHANGE IN ELECTRICAL-RESISTIVITY OF POLYCRYSTALLINE YSZ AND CSZ

Time-dependent change in the electrical resistivity of polycrystalline YSZ (10 mol % Y2O3) and CSZ (17 mol % CaO) was investigated by use of 4-terminal dc resistance-time data obtained from bridge -shaped samples at 1100°-1350°C in air. The change in resistivity consists of the bulk resistance change and the grain boundary resistance change, and the bulk resistance change is completed in a short time as compared to the grain boundary resistance change. The changes in both resistances can be expressed by exponential functions of time, respectively. For example, the expression for the increase in resistivity is as follows: ρ{variant}(t)=A-B1exp(-K2t)-B2exp(-K2t), where A, B1, K1, B2 and K2 are positive constants, t is the time elapsed, and the subscripts 1 and 2 are used to designate the relations to the bulk resistance and the grain boundary resistance, respectively. © 1990.