Hydrothermal Single Crystal Growth and Structural Investigation of the Stuffed Tridymite Family as NLO materials
Hydrothermal Single Crystal Growth and Structural Investigation of the Stuffed Tridymite Family as NLO materials
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DOI：
10.1016/j.jallcom.2022.164634
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发表时间：
2022-03
影响因子：
6.2
通讯作者：
R. Terry;Daniel Vinton;C. McMillen;Xiangfeng Chen;Lin Zhu;J. Kolis
中科院分区：
文献类型：
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作者：
R. Terry;Daniel Vinton;C. McMillen;Xiangfeng Chen;Lin Zhu;J. Kolis
研究了填充鳞石英的结构、晶体生长和非线性光学性质。式ABCO 4的填充鳞石英，其中A分别是碱金属离子和BandCare第13族和第14族金属离子，形成了广泛的一系列结构，所有这些结构都是基于母体鳞石英（SiO2）结构的对称性破缺。在所有情况下，碱金属离子都存在于由金属离子四面体的六元环形成的平行于轴的通道中。通过B/C位的有序排列、四面体的交错和重叠、四面体相对于轴的上/下取向以及六元环的扭曲，可以形成大量的结构。这些对称性破缺步骤可以混合和匹配形成许多不同的结构，并且几乎都在极性无心空间群中。中心对称晶体形成的主要原因是B/C位的无序。当位置有序时，大多数结构是偏心的，具有极轴。大多数产品的高质量单晶可以使用高压水热法生长。初步的NLO实验表明，化合物是偏心的，但具有低的NLO转换，这是预期由于低极化率的构建块。极高比例的偏心结构类型，以及将结构与非常大且灵活的鳞石英结构类的系统变化相关联的能力，表明这可以作为设计具有许多其他有用物理性质的晶体的起点。
The structures, crystal growth and preliminary NLO properties of a broad class of compounds known as the stuffed tridymites are investigated. The stuffed tridymites of the formulaABCO4, where A are the alkali metal ions andBandCare Group 13 and 14 metal ions, respectively, form an extensive series of structures, all of which are based on symmetry breaking of the parent tridymite (SiO2) structure. In all cases the alkali ion resides in channels running parallel to thec-axis formed from six-membered rings of tetrahedra of the metal ions. A large array of structures can be formed though combinations of ordering of theB/Csites, staggered and eclipsed tetrahedra, up/down orientations of the tetrahedra relative to thec-axis, and distortions of the six-membered rings. These symmetry breaking steps can be mixed and matched to form many different structures, and nearly all are in polar acentric space groups. The primary cause of centrosymmetric crystal formation is disorder of theB/Csites. When the sites are well ordered most of the structures are acentric with polar axes. High quality single crystals of most products can be grown using a high pressure hydrothermal method. Preliminary NLO experiments indicate that the compounds are acentric, but have low NLO conversions, which is expected due to the low polarizability of the building blocks. The extremely high percentage of polar acentric structure types, and the ability to correlate the structures to systematic variations of the very large and flexible tridymite structural class, suggests that this can serve as a starting point for designing crystals with many other useful physical properties.