Research on the phase decomposition of LuxY1−xAlO3:Ce crystals at high temperatures

Cerium-doped lutetium ortho-aluminate LuAlO3:Ce crystal is a good scintillator with excellent properties, while the single crystal is very difficult to grow and the phase decomposition mechanism remains unknown. In this paper, based on the analyses of high-temperature DTA and X-ray diffraction (XRD), it is supposed that LuAlO3:Ce melts at 1905 °C, it tends to decompose when the temperature goes above 1200 °C, and the decomposition products are Lu3Al5O12:Ce and Lu4Al2O9:Ce. This decomposition is an irreversible endothermic reaction. This phenomenon is suggested to be caused by the unfitness of the radius of Lu3+ ion for the perovskite-type structure of LuAlO3, and this is the intrinsic cause for the instability of LuAlO3:Ce. Introducing ions with larger radius (such as Y3+) into LuAlO3:Ce crystal may increase its phase stability.