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Updated: May 27, 2026
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Published on: April 14, 2020
Structure change induced by terminal sulfur in noncentrosymmetric La2Ga2GeS8 and Eu2Ga2GeS7 and nonlinear-optical
Mei-Chun Chen1, Peng Li, Liu-Jiang Zhou
1Key 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.
Abstract:
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.
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