Two new cesium selenites containing TaO₆ or TiO₄F₂ octahedra, namely, Cs(TaO₂)₃(SeO₃)₂ (1) and Cs(TiOF)₃(SeO₃)₂ (2), have been prepared using standard high temperature solid-state method and hydrothermal reaction, respectively. Compound 1 crystallizes in P3̅m1 and features an unusual [(TaO₂)₃(SeO₃)₂]⁻ sandwich-like double layer in which two [Ta(1)O₃(SeO₃)]^3– layers are bridged by central Ta(2)O₆ octahedra via corner-sharing, whereas Cs(TiOF)₃(SeO₃)₂ with a polar space group P6₃mc features an interesting hexagonal tungsten oxide (HTO) layered topology and presents a strong second harmonic generation (SHG) of about 5 × KDP (KH₂PO₄), which is much larger than those of A(VO₂)₃(QO₃)₂ (A = K, Tl, Rb, Cs, or NH₄; Q = Se, Te) with a similar HTO layered structure. Cs(TiOF)₃(SeO₃)₂ is also type-I phase matching. The SHG of above-mentioned HTO materials can be enhanced greatly with the replacement of VO₆ octahedra by TiO₄F₂ octahedra. Furthermore, thermal stabilities, UV–vis diffuse reflectance spectra, infrared spectra, relationship between crystal structure and SHG, and theoretical calculations were also reported.

中文翻译：

---

铯（TAO ₂）₃（SEO ₃）₂和Cs（TIOF）₃（SEO ₃）₂：结构和二次谐波变化引起由不同d ⁰ -TM协调八面体

使用标准品制备了两种新的含TaO ₆或TiO ₄ F ₂八面体的硒化铯，分别为Cs（TaO ₂）₃（SeO ₃）₂（1）和Cs（TiOF）₃（SeO ₃）₂（2）。高温固态法和水热反应。化合物1个结晶在P 3米1，并设有一个不寻常的[（TAO ₂）₃（SEO ₃）₂ ] ^-夹心状双层结构，其中两个[Ta（1）O ₃（SeO ₃）] ^3–层通过中心Ta（2）O ₆八面体通过角共享桥接，而Cs（TiOF）₃（SeO ₃）₂极性空间群为P 6 ₃ mc的人具有有趣的六角形氧化钨（HTO）分层拓扑结构，并呈现出约5×KDP（KH ₂ PO ₄）的强二次谐波（SHG），比A的大得多。 （VO ₂）₃（QO ₃）₂（A = K，Tl，Rb，Cs或NH ₄; Q = Se，Te）具有类似的HTO分层结构。CS（TIOF）₃（SEO ₃）₂也I型相位匹配。通过用TiO ₄ F ₂八面体代替VO ₆八面体，可以大大提高上述HTO材料的SHG 。此外，还报道了热稳定性，紫外可见漫反射光谱，红外光谱，晶体结构与SHG之间的关系以及理论计算。