Sun Mengran, Zhang Xingyu, Xing Wenhao, Li Zhuang, Liu Wenhao, Lin Zheshuai, Yin Wenlong, Yao Jiyong
Beijing Center for Crystal Research and Development, Key Lab of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P.R. China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
Inorg Chem. 2021 Oct 4;60(19):14793-14802. doi: 10.1021/acs.inorgchem.1c02045. Epub 2021 Sep 16.
Demands for IR birefringent materials are increasing due to the rapid developments of IR laser applications. Herein, two new chain tellurides β-BaGaTe and BaGaGeTe have been discovered. β-BaGaTe crystallizes in the orthorhombic space group (no. 74) with unit cell constants of = 23.813(3) Å, = 11.9673(19) Å, and = 6.7215(9) Å, while BaGaGeTe crystallizes in the monoclinic space group 2/ (no. 14) with unit cell constants of = 13.6540(3) Å, = 9.6705(2) Å, and = 23.1134(7) Å. The structure of β-BaGaTe can be considered to be the antiparallel arrangement of one-dimensional (1D) [GaTe] chains formed by edge-sharing GaTe tetrahedra, which are separated by Ba cations. In the crystal structure of BaGaGeTe, two kinds of 1D chains, namely chain 1 [(GaGe)Te] and chain 2 [(GaGe)Te], are stacked alternately and put together by the coulomb force with Ba cations. In addition, First-principles calculations indicate that β-BaGaTe has a large birefringence, ∼0.325 at 2050 nm, derived from the superposition of the polarizabilities of GaTe tetrahedra, implying that it has potential as an IR birefringent material. This work may provide some guidance for exploring new IR birefringent crystals.
由于红外激光应用的快速发展，对红外双折射材料的需求正在增加。在此，发现了两种新的链状碲化物β-BaGaTe和BaGaGeTe。β-BaGaTe结晶于正交空间群（编号74），晶胞常数为 = 23.813(3) Å， = 11.9673(19) Å， = 6.7215(9) Å，而BaGaGeTe结晶于单斜空间群2/ （编号14），晶胞常数为 = 13.6540(3) Å， = 9.6705(2) Å， = 23.1134(7) Å。β-BaGaTe的结构可被认为是由边共享GaTe四面体形成的一维（1D）[GaTe]链的反平行排列，这些链被Ba阳离子隔开。在BaGaGeTe的晶体结构中，两种1D链，即链1 [(GaGe)Te]和链2 [(GaGe)Te]，交替堆叠并通过与Ba阳离子的库仑力结合在一起。此外，第一性原理计算表明β-BaGaTe具有较大的双折射，在2050 nm处约为0.325，这源于GaTe四面体极化率的叠加，这意味着它有潜力成为一种红外双折射材料。这项工作可能为探索新型红外双折射晶体提供一些指导。
