Key Laboratory of Optoelectronic Materials Chemistry and Physics and ∥State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou, Fujian 350002, China.
J Am Chem Soc. 2014 Jun 18;136(24):8560-3. doi: 10.1021/ja504319x. Epub 2014 Jun 10.
It is challenging to explore deep-ultraviolet (deep-UV) nonlinear optical (NLO) materials that can achieve a subtle balance between deep-UV transparency and high NLO activity. Known deep-UV NLO materials are almost exclusively limited to borates, except few newly discovered phosphates despite their small NLO activities. Here we report two asymmetric phosphates, RbBa2(PO3)5 (I) and Rb2Ba3(P2O7)2 (II), which feature [PO3]∞ chains and P2O7 dimers formed by condensation of PO4 units, respectively. Remarkably, I achieves the desired balance, with the shortest deep-UV absorption edge at 163 nm and the largest NLO activity of 1.4 × KDP (KH2PO4) in deep-UV NLO phosphates. According to first-principles calculations, the enhanced macroscopic SHG response of I can be attributed to the [PO3]∞ chains which exhibit significantly larger microscopic SHG coefficients as compared with the P2O7 dimers.
探索在深紫外（深 UV）透明度和高光非线性光学（NLO）活性之间取得微妙平衡的深 UV NLO 材料颇具挑战性。已知的深 UV NLO 材料几乎完全限于硼酸盐，尽管它们的 NLO 活性很小，但除了少数新发现的磷酸盐外，几乎没有其他磷酸盐。在这里，我们报告了两种不对称的磷酸盐，RbBa2(PO3)5（I）和 Rb2Ba3(P2O7)2（II），它们分别由 [PO3]∞链和由 PO4单元缩合形成的 P2O7二聚体组成。值得注意的是，I 实现了所需的平衡，其深 UV 吸收边缘最短为 163nm，NLO 活性最大，在深 UV NLO 磷酸盐中为 1.4×KDP（KH2PO4）。根据第一性原理计算，I 的增强宏观二次谐波响应可归因于 [PO3]∞链，与 P2O7二聚体相比，其表现出显著更大的微观二次谐波系数。
