The Aging Characteristics in Perovskite-Type Ferroelectric Ceramics

Abstract

The aging characteristics of the physical constants have been studied under various biasing and temperature conditions for the ceramics of BaTiO₃ and Pb(Zr-Ti)O₃ system. The change of the dielectric constant is assumed to be divided into two parts: one is the increase due to the 90°-back-rotation of domains in connection with the dielectric anisotropy and the other is the decrease mainly due to the 180°-back-reversal in relation to the domain clamping effect. The aging of the dielectric constant has been calculated under the above assumption using the measured values of electrostriction and polarization. The calculated values agree well with the observed ones both in BaTiO₃ and Pb(Zr-Ti)O₃ families ceramics, and the aging characteristics can be explained by the present treatment. The aging rate of the dielectric constant does not increase monotonically with temperature for unpoled Pb(Zr-Ti)O₃ families ceramics, and suggests that in this case aging cannot be interpreted with a simple thermally activated process.