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

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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 (σion,σelec) are extracted from the impedance spectra using an equivalent circuit based on the premise of mixed conduction. In the temperature range 500–700 °C, a change in local pO2 mainly affects σelec, suggesting that the samples are ionically compensated, i.e., [VO••]=[VPb″]. The chemical diffusion coefficient, D̃, 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, D̃=2.0×10−4 cm2 s−1 (700 °C, in air).