Mixed conduction and chemical diffusion in a Pb(Zr0.53,Ti0.47)O3 buried capacitor structure

Impedance spectroscopy is performed on a buried capacitor structure composed of a PZT-0.75% Nb ceramic with platinum electrodes. The ionic and electronic conductivities (sigma(ion),sigma(elec)) are extracted from the impedance spectra using an equivalent circuit based on the premise of mixed conduction. In the temperature range 500-700 degrees C, a change in local pO(2) mainly affects sigma(elec), suggesting that the samples are ionically compensated, i.e., [V-O(center dot center dot)]=[V-Pb(')]. The chemical diffusion coefficient, D approximate to, is obtained by a conductivity relaxation technique assuming two-dimensional diffusion geometry. In comparison to BaTiO3, or SrTiO3, the chemical diffusivity is found to be relatively high, D approximate to=2.0x10(-4) cm(2) s(-1) (700 degrees C, in air).