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The noncentrosymmetric structure is one prerequisite of a nonlinear optical (NLO) material. Here, a sulfate Cs2Ca2(SO4)3 with a noncentrosymmetric structure was synthesized by high‐temperature solid‐state reaction, and its crystals were grown by spontaneous crystallization. Single‐crystal X‐ray diffraction indicates that Cs2Ca2(SO4)3 features a three‐dimensional framework constituted by corner‐sharing CaO6 octahedra and SO4 tetrahedra. Optical characterizations suggest that Cs2Ca2(SO4)3 is transparent down to 200 nm and exhibits a moderate second‐order NLO response of about 0.6 × KH2PO4. Electronic band structure calculations were performed to elucidate the optical origin. Furthermore, the title compound has good thermal stability of up to about 1000 K, which is greatly higher than those of NLO sulfates reported recently. This work may shed useful light on the development of new NLO sulfates with high thermal stability. [ABSTRACT FROM AUTHOR]

The noncentrosymmetric structure is one prerequisite of a nonlinear optical (NLO) material. Here, a sulfate Cs2Ca2(SO4)3 with a noncentrosymmetric structure was synthesized by high‐temperature solid‐state reaction, and its crystals were grown by spontaneous crystallization. Single‐crystal X‐ray diffraction indicates that Cs2Ca2(SO4)3 features a three‐dimensional framework constituted by corner‐sharing CaO6 octahedra and SO4 tetrahedra. Optical characterizations suggest that Cs2Ca2(SO4)3 is transparent down to 200 nm and exhibits a moderate second‐order NLO response of about 0.6 × KH2PO4. Electronic band structure calculations were performed to elucidate the optical origin. Furthermore, the title compound has good thermal stability of up to about 1000 K, which is greatly higher than those of NLO sulfates reported recently. This work may shed useful light on the development of new NLO sulfates with high thermal stability. [ABSTRACT FROM AUTHOR]

A series of noncentrosymmetric sulfides Ln8Sb2S15 (Ln = La, Pr, Nd) were prepared from stoichiometric mixtures of the elements at 1223 K in an evacuated silica tube. The compounds Ln8Sb2S15 with Ln = La and Nd are isostructural to Pr8Sb2S15 and crystallize in the tetragonal noncentrosymmetric space group I41cd. Their structure contains discrete [SbS3]3- trigonal pyramids separated by Ln3+ cations and S2- anions. La8Sb2S15 shows second harmonic generation with intensities 1.2 times that of the commercially used IR NLO (nonlinear optics) material AgGaS2 (at 2.05 μm laser). It exhibits excellent thermal stability up to 663 °C. Studies with UV/Vis-NIR diffuse reflectance spectroscopy show that La8Sb2S15 has an optical gap of around 2.3 eV, and a DFT study indicates a direct band gap with an electronic transfer excitation of S 3p electrons to a La 5d orbital. [ABSTRACT FROM AUTHOR]

The noncentrosymmetric borate CsCdBO3 was synthesized by a solid-state reaction, and its structure was determined by single-crystal X-ray diffraction. The crystal structure is a complicated three-dimensional network composed of CdO6 octahedra, CsO6 octahedra, and BO3 triangles. Interestingly, CsCdBO3 crystallizes in the cubic space group P213, which is quite rare for borate-containing anisotropic polarized planar BO3 groups. Furthermore, the IR spectrum confirms the presence of BO3 groups. Second harmonic generation (SHG) measurements on powder samples reveal that the SHG response of CsCdBO3 is approximately 0.5 × KDP (KH2PO4). Thermal analysis and UV/Vis/NIR diffuse reflectance spectroscopy data, as well as electronic band structure calculations, are also reported. [ABSTRACT FROM AUTHOR]