Dislocation response to electric fields in strontium titanate: A mesoscale indentation study

Abstract

Dislocations in perovskite oxides have drawn increasing research interest due to their potential of tuning functional properties of electroceramics. Open questions remain regarding the behavior of dislocations concerning their stability under strong externally applied electric fields. In this study, we investigate the dielectric breakdown strength of nominally undoped SrTiO3 crystals after the introduction of high-density dislocations. The dislocation-rich samples are prepared using the Brinell scratching method, and they consistently exhibit lower dielectric breakdown strength as well as a larger scatter in the breakdown probability. We also study the impact of electric field on the introduction and movement of dislocations in SrTiO3 crystals using Brinell indentation coupled with an electric field of 2 kV/mm. No changes on the dislocation plastic zone size, depth, and dislocation distribution are observed under this electric field. Based on the charge state of the dislocations in SrTiO3 as well as the electrical and thermal conductivity modified by dislocations, we discuss the forces induced by the electric field to act on the dislocations to underline the possible mechanisms for such dislocation behavior.

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