Failure Mechanisms in Ferroelectric and Nonlinear Dielectrics

摘要

Breakdown fields in single-crystal SrTiO3 have been measured over a temperature range of -195C to 100C and the results are compared with the predictions of Frohlich's theory. Measurements are consistent with the theory on magnitude and temperature dependence of breakdown field except at the lower temperatures where the disturbing effects of electrostrictive strain are considerable. A marked variation of dielectric and resistive properties of SrTiO3 samples is observed to be dependent upon the sample's history and a qualitative explanation of the effect is proposed. Bulk diffusion constants in annealed and unannealed SrTiO3 have been measured directly. The diffusivity is found to be dependent upon dislocation density but is several orders of magnitude too low to explain the rapid oxidation rates observed in SrTiO3. Alternative explanations of this discrepancy are put forward. (Author)