Thermal behavior of borate BaBiBO4

The thermal behavior of barium and bismuth borate BaBiBO4 is studied by X-ray powder and single-crystal diffraction in a wide temperature range, as well as by the methods of differential scanning calorimetry and dielectric spectroscopy. Thermal expansion is anisotropic, which is caused by the orientation of BO3 boron-oxygen groups. With increasing temperature, the degree of anisotropy of thermal expansion increases up to negative. In the temperature range of 700–800 K, an anomaly of the dielectric properties is observed, accompanied by the change of the temperature dependence of the coefficients of thermal expansion and the heat capacity.