Ferroelectric properties and phase-transition dynamics of Bi₄Ti₃O₁₂-based single crystals

Abstract

The domain structure in the single crystals of (Bi₄Ti₃O₁₂:BiT) and vanadium-containing BiT was investigated by optical microscope combined with Micro-Raman spectroscopy. The strong anisotropy of the soft mode(s) at 25-30 cm^-1 was observed and the intensity of the soft mode along a axis was much higher than that along b axis. The complex 90-deg domain structure was determined in a-b plane of single crystals. The mobility of the domain wall in V-containing BIT was much higher than that in BIT, and the speed of domain wall motion near Curie temperature (=675°C) was roughly estimated to be 20μm/s, which was four times as high as that in BIT.