Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People's Republic of China.
Inorg Chem. 2011 Dec 19;50(24):12402-4. doi: 10.1021/ic2020513. Epub 2011 Nov 16.
Two new noncentrosymmetric quaternary sulfides, La(2)Ga(2)GeS(8) (1) and Eu(2)Ga(2)GeS(7) (2), have been synthesized by high-temperature solid-state reactions. The structure change on going from 1 to 2 to the known Li(2)Ga(2)GeS(6) (3) nicely shows that the reduced cation charge-compensation requirement causes a decrease in the number of terminal S atoms per formula, which is a key to determining the connectivity of the GaS(4) and GeS(4) building units. Powder sample 2 exhibits a strong second-harmonic-generation (SHG) response of about 1.6 times the benchmark AgGaS(2) at 2.05 μm laser radiation, a non type I phase-matchable behavior, and a comparable transparency region. The SHG intensities of these compounds originate from the electronic transitions from S 3p states to La/Eu/Li-S, Ga-S, and Ge-S antibonding states according to Vienna ab initio simulation package studies.
La(2)Ga(2)GeS(8)（1）和 Eu(2)Ga(2)GeS(7)（2）。从 1 到 2 的结构变化很好地表明，减少阳离子电荷补偿要求导致每个化学式中终端 S 原子的数量减少，这是决定 GaS(4)和 GeS(4)结构单元连接方式的关键。粉末样品 2 在 2.05μm 激光辐射下表现出约 1.6 倍于基准 AgGaS(2)的强二次谐波产生（SHG）响应，非类Ⅰ相匹配行为和相当的透明度区域。根据维也纳从头算模拟包的研究，这些化合物的 SHG 强度源于 S 3p 态到 La/Eu/Li-S、Ga-S 和 Ge-S 反键态的电子跃迁。
