Temperature and pressure dependence of dielectric properties of ceramic Pb(Fe(1/2)Ta(1/2))O(3)

Dielectric properties such as the real epsilon" and imaginary epsilon" parts of the complex permittivity and the spontaneous polarization P(N) of ceramic Pb(Fe(1/2)Ta(1/2))O(3) with the diffuse phase transition (DPT) were measured under pressures up to 6 kbar. The value of epsilon" shows a broad maximum at a temperature T(m) (mean Curie temperature). As the pressure increases, T(m) of the maximum epsilon" (epsilon"(max)) and the value of epsilon"(max) decrease, and the shape of the maximum in epsilon" around T(m) becomes broader. The pressure coefficient of T(m) is about -3.4 K/kbar. The small heat effect associated with the DPT was observed around T(m). The temperature and pressure dependence of epsilon" and P(s ) is explained in terms of a phenomenological theory using statistical treatments based on a Gaussian distribution of the local Curie temperature. The value of the standard deviation sigma describing the intensity of the DPT is 25 K and increases with increasing pressure.