Research on phase transition behavior of lutetium orthoborate LuBO₃

Abstract

Cerium-doped lutetium orthoborate LuBO₃ : Ce crystal is a promising scintillator with excellent properties, but the single crystal is difficult to grow because of the phase transition. In this article, the reported high-temperature (HT) vaterite phase was proved to exist at a low temperature (below 1200°C). Moreover, the real HT phase of LuBO₃ was identified for the first time. The observed HT phase structure of LuBO₃ was isostructural with the hexagonal structure of YbBO₃ with space group P6₃22(182). The temperature dependence of the lattice constant and unit cell of the above phase structures were also investigated. The relative stability of calcite phase of LuBO₃ could associate with fitness of the radius of Lu³⁺ ion for the six-coordination structure.

Keywords:

• lutetium orthoborate
• scintillation crystals
• phase transition
• thermal stability
• Czochralski method

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant No. 50902145), the Natural Science Foundation of Shanghai (Grant No. 09ZR1435800), and the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. SCX200701).