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

Abstract

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).

Resistance variation in donor-doped PZT stacks with Cu inner electrodes under high field stress

“…These values are also within the extrapolated range of chemical diffusion coefficients reported in Ref. [45] for a similarly doped though differently prepared PZT (about 10 −6 cm 2 /s).…”

“…In our study, the relaxation is also much slower than the conductivity decrease and the activation energy of τ 2 is of the order of 1.1 eV. This is close to the value of about 1.2 eV, which can be evaluated from chemical diffusion data of a similarly doped PZT material [45].…”

“…Such a detailed understanding is not available for many other perovskite-type electroceramics. For example, it is still far from being quantified under which doping, pressure and temperature conditions ionic or electronic conduction prevails in PZT and related materials [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45], and also to what extent grain boundaries are either highly resistive or represent highly conductive paths for charge transport. Only recently, it was shown that in donor-doped PZT very pronounced oxygen tracer diffusion along grain boundaries may take place [46,47].…”

Synergistic effect of rare-earth elements on the dielectric properties and reliability of BaTiO 3 -based ceramics for multilayer ceramic capacitors

“…[37][38][39] in the inset illustration. The model is composed of an electronic rail which corresponds to the grain and grain boundary impedance in the high frequency region, and an ionic rail that includes a Warburg impedance (W s ) in the low frequency region.…”

“…The presence of the low frequency arc in the complex impedance spectra indicates an ionic space charge polarization [35,36]. Such a response occurs due to the particular charged defects, in this case oxygen vacancies, being blocked at the electrodes, whereas the electronic conduction is reversible [36][37][38].…”