In-situ observation of needle domain evolution in barium titanate single crystals

We report in-situ optical observations of the ferroelastic switching in a barium titanate single crystal under compressive stress. Optical micrographs were captured in two regions showing distinct arrangements of domains. Coarsely spaced needle domains in a matrix consisting of a differently oriented large single domain were found to retreat under the application of compressive stress of around 1–2 MPa. However, a comb of closely spaced needle domains was found to be more stable, retreating only slightly under a similar magnitude of applied load. The observations show that the pattern of needle domains influences the ferroelastic switching process and the observed coercive stress can depend strongly on domain arrangement.