Bera Tarun K, Jang Joon I, Ketterson John B, Kanatzidis Mercouri G
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2009 Jan 14;131(1):75-7. doi: 10.1021/ja807928d.
The strongly anisotropic thioarsenates A(3)Ta(2)AsS(11) are stabilized in a polysulfide flux. All compounds contain the same parallel (1)/(infinity)[Ta(2)AsS(11)(3-)] polymeric anionic chains, but the size of the alkali-metals has a profound effect on the packing of the chains. The K(+) or Rb(+) favor noncentrosymmetric packing of the chains, whereas the larger Cs(+) favors the centrosymmetric packing. The chains feature the combination of two asymmetric units [Ta(2)S(11)] and [AsS(3)] and exhibit strong nonlinear optical (NLO) second harmonic generation (SHG) response. Polycrystalline samples exhibit is up to approximately 15 times stronger SHG than that of commercially used AgGaSe(2).
强各向异性硫代砷酸盐A(3)Ta(2)AsS(11)在多硫化物熔剂中得以稳定。所有化合物都含有相同的平行(1)/(∞)[Ta(2)AsS(11)(3-)]聚合阴离子链，但碱金属的大小对链的堆积有深远影响。K(+)或Rb(+)有利于链的非中心对称堆积，而较大的Cs(+)则有利于中心对称堆积。这些链具有两个不对称单元[Ta(2)S(11)]和[AsS(3)]的组合，并表现出强烈的非线性光学（NLO）二次谐波产生（SHG）响应。多晶样品的SHG比商业使用的AgGaSe(2)强约15倍。
