Zhang, Jian-Han Hu, Chun-Li Xu, Xiang Kong, Fang Mao, Jiang-Gao New Second-Order NLO Materials Based on Polymeric Borate Clusters and GeO<sub>4</sub> Tetrahedra: A Combined Experimental and Theoretical Study Three novel rubidium borogermanates with three types of noncentrosymmetric structures, namely, RbGeB<sub>3</sub>O<sub>7</sub>, Rb<sub>2</sub>GeB<sub>4</sub>O<sub>9</sub>, and Rb<sub>4</sub>Ge<sub>3</sub>B<sub>6</sub>O<sub>17</sub>, have been synthesized by high-temperature solid-state reactions in platinum crucibles. The structure of RbGeB<sub>3</sub>O<sub>7</sub> features a three-dimensional (3D) anionic framework composed of cyclic B<sub>3</sub>O<sub>7</sub> groups corner-sharing GeO<sub>4</sub> tetrahedra. The structure of Rb<sub>2</sub>GeB<sub>4</sub>O<sub>9</sub> shows a 3D anionic framework based on B<sub>4</sub>O<sub>9</sub> clusters connected by GeO<sub>4</sub> tetrahedra via corner sharing. The structure of Rb<sub>4</sub>Ge<sub>3</sub>B<sub>6</sub>O<sub>17</sub> is a novel 3D anionic framework composed of cyclic B<sub>3</sub>O<sub>8</sub> groups, Ge<sub>2</sub>O<sub>7</sub> dimers, and GeO<sub>4</sub> tetrahedra that are interconnected via corner sharing. Second harmonic generation (SHG) measurements indicate that RbGeB<sub>3</sub>O<sub>7</sub>, Rb<sub>2</sub>GeB<sub>4</sub>O<sub>9</sub>, and Rb<sub>4</sub>Ge<sub>3</sub>B<sub>6</sub>O<sub>17</sub> display moderate SHG responses that are approximately 1.3, 2.0, and 1.3 × KH<sub>2</sub>PO<sub>4</sub> (KDP), respectively, which are slightly smaller than those from theoretical calculations (about 3.7, 2.8, and 2.4 × KDP, respectively). GeO 4 tetrahedra;RbGeB 3O features;Ge 2O dimers;RbGeB 3O Rb 2GeB;framework;2PO;NLO;Rb 4Ge display;SHG;Theoretical StudyThree novel rubidium borogermanates;novel 3 D;KDP;KH;B 4O clusters;Rb 4Ge;GeO 4 Tetrahedra;cyclic B 3O groups;Polymeric Borate Clusters 2011-03-07
    https://acs.figshare.com/articles/dataset/New_Second_Order_NLO_Materials_Based_on_Polymeric_Borate_Clusters_and_GeO_sub_4_sub_Tetrahedra_A_Combined_Experimental_and_Theoretical_Study/2686291
10.1021/ic102451n.s002