Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR. China.
Dalton Trans. 2011 Apr 14;40(14):3610-5. doi: 10.1039/c0dt01756f. Epub 2011 Mar 4.
The new compound BaAl(4)Se(7) has been synthesized by solid-state reaction. It crystallizes in the non-centrosymmetric space group Pc and adopts a three-dimensional framework built from AlSe(4) tetrahedra and with Ba(2+) cations in the cavities. The material has a large band gap of 3.40(2) eV. It melts congruently at 901 °C and exhibits a second harmonic generation (SHG) response at 1 μm that is about half that of AgGaS(2). From a band structure calculation, BaAl(4)Se(7) is a direct-gap semiconductor with strong hybridization of the Al 3s, Al 3p, and Se 4p orbitals near the Fermi level. The calculated birefractive index is about 0.05 for wavelength longer than 1 μm and major SHG tensor elements are: d(15) = 5.2 pm V(-1) and d(13) = 4.2 pm V(-1).
新型化合物 BaAl(4)Se(7) 通过固态反应合成。它在非中心对称空间群 Pc 中结晶，采用由 AlSe(4)四面体和空腔中的 Ba(2+)阳离子构建的三维框架。该材料具有 3.40(2) eV 的大带隙。它在 901°C 下完全熔化，并在 1 μm 处表现出二次谐波产生 (SHG) 响应，约为 AgGaS(2)的一半。从能带结构计算来看，BaAl(4)Se(7)是一种直接带隙半导体，在费米能级附近，Al 3s、Al 3p 和 Se 4p 轨道的杂化很强。计算得出的双折射指数对于波长大于 1 μm 的光约为 0.05，主要的 SHG 张量元素为：d(15)=5.2 pm V(-1)和 d(13)=4.2 pm V(-1)。
