Song Seung Yoon, Ok Kang Min
Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Republic of Korea.
Inorg Chem. 2015 May 18;54(10):5032-8. doi: 10.1021/acs.inorgchem.5b00653. Epub 2015 Apr 27.
Four new stoichiometrically equivalent quaternary scandium selenites, ASc(SeO3)2 (A = Na, K, Rb, and Cs) have been hydrothermally synthesized using A2CO3, Sc(NO3)3·xH2O (or ScO3), and SeO2 as starting materials. All four materials share similar bond networks that are composed of corner-shared distorted ScO6 octahedra and SeO3 trigonal pyramids. However, each material reveals different frameworks and centricities. Detailed structural analysis suggests that the structural variation is attributed to the difference in size and subsequent coordination number for the alkali metal cations. Powder second-harmonic generation (SHG) measurements on noncentrosymmetric (NCS) RbSc(SeO3)2 show that the compound has an SHG efficiency similar to that of (NH4)H2PO4. The observed SHG efficiency is due to the remaining net polarization after cancellation of oppositely aligned moments for SeO3 and ScO6 groups. Thorough characterizations such as spectroscopic, thermal, and elemental analyses for the new materials are presented as are dipole moment and out-of-center distortion calculations.
以A₂CO₃、Sc(NO₃)₃·xH₂O（或ScO₃）和SeO₂为原料，水热合成了四种化学计量比等效的新型钪亚硒酸盐ASc(SeO₃)₂（A = Na、K、Rb和Cs）。这四种材料都具有相似的键网络，由角共享的扭曲ScO₆八面体和SeO₃三角锥组成。然而，每种材料都呈现出不同的结构框架和中心对称性。详细的结构分析表明，结构变化归因于碱金属阳离子的尺寸差异以及随之而来的配位数差异。对非中心对称（NCS）的RbSc(SeO₃)₂进行的粉末二次谐波产生（SHG）测量表明，该化合物的SHG效率与(NH₄)H₂PO₄相似。观察到的SHG效率是由于SeO₃和ScO₆基团相反排列的矩抵消后剩余的净极化。本文还介绍了对新材料进行的诸如光谱、热和元素分析等全面表征，以及偶极矩和离中心畸变计算。
