文摘
Water molecule-driven reversible phase transitions up to 450 °C have been observed for the first time in a novel selenite crystal, LiSc(SeO3)2·H2O, through single-crystal-to-single-crystal (SCSC) transformations. Single crystal X-ray diffraction suggests that LiSc(SeO3)2·H2O (P2/c) transforms to LiSc(SeO3)2·0.5H2O (P1̅), LiSc(SeO3)2·0.25H2O (P1̅), and α-LiSc(SeO3)2 (I–42d) at 170–190, 200–230, and 240–450 °C, respectively. The structural evolution is attributable to the different positions of Li+ cations within the eight-membered ring (8-MR) channel, in which the amount of water molecules plays a key role in determining the coordination environment and the subsequent location of Li+ cations. Further heating of the crystal to 500 °C results in a remarkably stable β-LiSc(SeO3)2 (R3̅).