High‐Temperature Phase Relations in the Lu2O3–Ta2O5 System

The compounds formed from the Lu2O3-Ta2O5 system in the composition range 25-60 mol% Ta2O5 were prepared by solid-state reaction from 1350 degrees C to 2058 degrees C, and the phase transitions were investigated by X-ray diffraction (XRD). Cubic Lu3TaO7, M-LuTaO4, M-LuTaO4, O-Ta2O5, and T-Ta2O5 are observed. With the temperature increase, there is an irreversible phase transition from M to M-LuTaO4 near 1770 degrees C in the composition of 30-52 mol% Ta2O5, and another phase transition from T-Ta2O5 to O-Ta2O5 at about 1685 degrees C when the ratio of Ta2O5 is >52 and 60 mol%. A phase diagram of the Lu2O3-Ta2O5 system in the range 0-100 mol% Ta2O5 was constructed. These results are helpful to explain the phase transition of Lu2O3-Ta2O5 system and design the preparation technique of LuTaO4 single crystal or ceramic scintillator, which may be applied in the fields of nuclear medicine and high-energy physics.