Eighteen new quaternary chalcogenides AGaM'Q4 (A+ = K+, Rb+, Cs+, Tl+; M'4+ = Ge4+, Sn4+; Q2- = S2-, Se2-) have been pre-pared by solid-state syntheses and structurally characterized using single-crystal X-ray diffraction techniques. These new phases crystallize in a variety of layered structure types. The tin analogues also adopt an extended three-dimensional net-work structure as polymorphs. The polymorphism and phase-stability in these cases were studied by thermal analysis and high-temperature in situ X-ray powder diffraction. All compounds are semiconductors with the colored selenides absorbing light in the infrared-green region (1.8 eV < Eg < 2.3 eV) and the mostly white sulfides absorbing light in the blue-ultraviolet range (2.5 eV < Eg < 3.6 eV). Based on third-harmonic generation (THG) measurements, the third-order nonlinear optical (NLO) susceptibilities χ(3) of the new and previously reported AGaM'Q4 compounds were determined. These measurements revealed an apparent correlation between the THG response of the sample and its band gap, rather than the crystal structure type. While low-gap materials possess higher nonlinearity in general, we found that layered orthorhombic RbGaGeS4 exhibits an impressive χ(3) value (about four times larger than that of AgGaS2) even with a large band gap and shows stability under ambient conditions with no significant irradiation damage.

中文翻译：

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分层和立方半导体 AGaM'Q4（A+ = K+、Rb+、Cs+、Tl+；M'4+ = Ge4+、Sn4+；Q2- = S2-、Se2-）和高三次谐波产生

十八种新的四元硫属化物 AGaM'Q4（A+ = K+、Rb+、Cs+、Tl+；M'4+ = Ge4+、Sn4+；Q2- = S2-、Se2-）已通过固态合成制备，并使用结构表征单晶 X 射线衍射技术。这些新相以各种层状结构类型结晶。锡类似物也采用扩展的三维网络结构作为多晶型物。通过热分析和高温原位 X 射线粉末衍射研究了这些情况下的多晶型和相稳定性。所有化合物都是半导体，有色硒化物吸收红外-绿色区域（1.8 eV < Eg < 2.3 eV）的光，大部分白色硫化物吸收蓝色-紫外范围内的光（2.5 eV < Eg < 3.6 eV）。基于三次谐波生成 (THG) 测量，确定了新的和以前报道的 AGaM'Q4 化合物的三阶非线性光学 (NLO) 磁化率 χ(3)。这些测量结果揭示了样品的 THG 响应与其带隙之间的明显相关性，而不是晶体结构类型。虽然低间隙材料通常具有更高的非线性，但我们发现，即使带隙很大，层状正交 RbGaGeS4 也表现出令人印象深刻的 χ(3) 值（大约是 AgGaS2 的四倍），并且在环境条件下表现出稳定性，没有显着的辐照损伤。