Thermodynamic and spectroscopic studies on the phase transition of BaHf(PO4)2

We have studied the thermal properties of BaHf(PO4)2 during the heating from the room temperature up to 1600 K by thermal analysis and drop calorimetry and up to 835 K by Raman spectroscopy. A phase transition appears at about 791 K during heating and at 744 K during cooling. For the high-temperature polymorph we determined the crystal class and the most likely space groups based on Raman spectroscopic data. The enthalpy of the transition was derived from the high-temperature heat capacity measurements.