Dielectric Properties of Ceramics in the System (Sr _0.50 Pb _0.25 Ca _0.25 )TiO ₃ ‐Bi ₂ O ₃ ·3TiO ₂ and Their Applications in a High‐Voltage Capacitor

Abstract

The dielectric behavior of (1‐ x )(Sr 0.5 Pb 0.25 Ca 0.25 ) TiO 3 ‐x(Bi 2 O 3 ·3TiO 2 ) was studied using x=O to 8.25 mol%. Around the point at which x equals 1.56 mol%, the following phenomena were observed: (1) At −;22°C, the weak field permittivity increased substantially with a dc bias field, becoming more than twice the zero bias value at a field of 3 kV/mm; (2) the permittivity peak shifted markedly toward a high temperature under a dc bias field; (3) relaxation behavior was evident; and (4) there are large hysteresis loops at low temperatures and double hysteresis loops, which seem to be related to a field‐enforced ferroelectric phase, in a wide temperature range. We used dielectrics with an optimized composition of x =4.30 mol% in a small, highly reliable, 15‐kV high‐voltage ceramic capacitor.