Ferroelastic Phase Transition of BiVO4 Single Crystals with Prominent W-Domain Walls by Stress-Strain Hysteresis Measurements

The phase transition of BiVO4 crystals with prominent W-domain walls was investigated by carrying out stress-strain hysteresis measurements. The change in the strain under a stress of 0.4 MPa was determined, and the non-linear behavior of the strain below T-C was found to be due to the switching of the ferroelastic domains. Above T-C, the strain has a minimum value, which indicates the presence of a paraelastic phase. A configuration of domain boundaries with two orientations separated by parallel lines was observed with polarizing microscopy in the ferroelastic phase, and these domain walls are not present in the paraelastic phase. Further, the stress-strain hysteresis loop has a shape typical of a ferroelastic phase below T-C, and above T-C has a shape indicative of a paraelastic phase. These results show that BiVO4 crystals undergo a ferroelastic phase transition near T-C = 255 degrees C.