Synthesis, structure and theoretical studies of a new ternary non-centrosymmetric β-LaGaS3
Synthesis, structure and theoretical studies of a new ternary non-centrosymmetric β-LaGaS3
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DOI：
10.1016/j.jssc.2009.11.030
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发表时间：
2010-02
影响因子：
3.3
通讯作者：
Peng Li;Longhua Li;Ling Chen;Li‐Ming Wu
中科院分区：
文献类型：
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作者：
Peng Li;Longhua Li;Ling Chen;Li‐Ming Wu
新的三元β-LaGaS3是由元素的化学计量混合物在1100℃下通过常规固相反应合成的，并在820℃下进行热处理。该化合物代表了一种新的结构类型，它结晶于非中心对称的正交空间群PNa21(No33)中，a=10.405(1)？，b=21.984(2)？，c=6.0565(5)？，Z=12，其特征是由La3+阳离子分隔的波状GaS4四面体链。讨论了标题化合物与其同分异构体单斜晶系α-LaGaS_3的结构差异。借助于WIEN2k程序，计算了两种LaGaS3的吸收光谱、电子结构以及折射率、吸收系数和反射率。计算得到的β-LaGaS_3的带隙和吸收边与实验测量结果吻合较好。检测到β-LaGaS_3的弱非线性光学响应。
New ternary β-LaGaS3has been synthesized from the stoichiometric mixture of elements by a conventional solid-state reaction at 1100°C and annealed at 820°C. This compound represents a new structure type that crystallizes in a non-centrosymmetric orthorhombic space group Pna21(No.33) with a=10.405(1)Å, b=21.984(2)Å, c=6.0565(5)Å, and Z=12, and features the wavy GaS4tetrahedron chains that are separated by La3+cations. Detailed structural differences between the title compound and its isomer, monoclinic α-LaGaS3, are discussed. With the aid of WIEN2k package, the absorption spectra and electronic structures as well as the refractive indexes, absorption coefficients and reflectivities of two types of LaGaS3have been calculated. The calculated band gap and the absorption edge of β-LaGaS3agree well with the experimental measurements. And a weak NLO response of β-LaGaS3has been detected.