Mixed conduction and chemical diffusion in a Pb(Zr_(0.53),Ti_(0.47))O_3 buried capacitor structure

摘要

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 (σ_(ion),σ_(elec)) are extracted from the impedance spectra using an equivalent circuit based on the premise of mixed conduction. In the temperature range 500-700 ℃, a change in local pO_2 mainly affects σ_(elec), suggesting that the samples are ionically compensated, i.e., [V_o~(··)] = [V_(pb)'']. The chemical diffusion coefficient, D, is obtained by a conductivity relaxation technique assuming two-dimensional diffusion geometry. In comparison to BaTiO_3, or SrTiO_3 the chemical diffusivity is found to be relatively high, D=2.0 × 10~(-4) cm~2 s~(-1) (700 ℃, in air).