BiVO₄: X-ray diffraction study of the thermal expansion

Abstract

The unit cell dimensions of bismuth vanadate have been measured in the temperature range 290 to 680 K using the X-ray Bond-type diffractometer. A ferroelastic, tetragonal-to-monoclinic phase transition at 525 K has been confirmed. Anomalies in the unit-cell parameters observed in an interval of about 50 K around the phase transition are connected with a creation of numerous tiny ferroelastic domains. The thermal expansion is nonlinear and fitted by the fourth-order polynomial. The components of the thermal expansion tensor, expressed in the principal axes system, have been calculated as a function of temperature.