0000000000530816
AUTHOR
M. Belkaoumi
Space-charge relaxation in perovskites.
We report a dielectric anomaly in several perovskites at intermediate frequencies 10\ensuremath{\le}f\ensuremath{\le}${10}^{7}$ Hz in the temperature range 400 \ifmmode^\circ\else\textdegree\fi{}C \ensuremath{\le}T\ensuremath{\le}800 \ifmmode^\circ\else\textdegree\fi{}C. We have found this dielectric maximum in more than 100 samples of various shapes and textures. This anomaly is shown to arise from a Debye dielectric dispersion that slows down following an Arrhenius law. We have established a link between this dielectric relaxation and the conductivity. We propose that it can be achieved through a space-charge model that quantitatively agrees with the experimental results in the lower temp…
Electron-relaxation-mode interaction in BaTiO3:Nb.
Dielectric relaxation was previously reported in ${\mathrm{BaTiO}}_{3}$ and ${\mathrm{BaTiO}}_{3}$:Fe single crystals at radio frequencies [M. Maglione et al., Phys. Rev. B 40, 11 441 (1989)]. We have measured the dielectric dispersion in four ${\mathrm{BaTiO}}_{3}$:Nb samples (${\mathit{x}}_{\mathrm{Nb}}$0.3 at. %) as a function of frequency (10f${10}^{9}$ Hz) and temperature (20T450 K). The electronic conductivity of ${\mathrm{BaTiO}}_{3}$:Nb enhances drastically the relaxation step at all temperatures. In the rhombohedral phase of ${\mathrm{BaTiO}}_{3}$:Nb (T180 K), an unusual slowing down of the relaxation motion is measured. The relaxation time increases to more than ${10}^{\mathrm{\en…