LiSc(SeO<sub>3</sub>)<sub>2</sub>·<i>x</i>H<sub>2</sub>O (0 ≤ <i>x</i> ≤ 1): New Selenites Revealing Water Molecule-Driven Extremely High Temperature Single-Crystal-to-Single-Crystal Transformations
作者:Seung Yoon Song、Kang Min Ok
DOI:10.1021/acs.cgd.6b00519
日期:2016.6.1
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).
首次观察到水分子驱动的可逆相变可达450°C,发生在一种新型硒酸盐晶体LiSc(SeO3)2·H2O中,通过单晶到单晶(SCSC)转变。单晶X射线衍射表明,LiSc(SeO3)2·H2O(P2/c)在170-190°C转变为LiSc(SeO3)2·0.5H2O(P1̅),在200-230°C转变为LiSc(SeO3)2·0.25H2O(P1̅),在240-450°C转变为α-LiSc(SeO3)2(I–42d)。结构演化归因于Li+阳离子在八元环(8-MR)通道内的不同位置,其中水分子的数量在决定配位环境及随后的Li+阳离子位置方面起到关键作用。进一步加热晶体至500°C会导致形成一个极为稳定的β-LiSc(SeO3)2(R3̅)。