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Updated: May 5, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
A Congruent-Melt Infrared Nonlinear Optical Crystal Na4SrAs2S8
Zhihui Xiong1, Aoge Yao2, Zhixi Li1
1College of Innovation and Entrepreneurship, Chengdu Normal University, Chengdu 611130, China.
Abstract:
A quaternary metal thioarsenate infrared (IR) nonlinear optical (NLO) compound Na4SrAs2S8 was successfully prepared by a high-temperature reaction method from stoichiometric agents. It crystallizes in the tetragonal P4n2 with the unit cell parameters a = 10.0393(3) Å, c = 6.9638(3) Å, and Z = 2, with the basic structural groups of isolated AsS4 tetrahedra. Compared with benchmark IR NLO crystal AgGaS2 (AGS), the title compound exhibits balanced optical properties of large band gap (3.05 eV vs. 2.60 eV) and considerable second harmonic generation response (0.95 × AGS). Moreover, the combined powder X-ray diffraction and differential scanning calorimetry analyses demonstrate that Na4SrAs2S8 is a congruent-melting compound with a low melting point of 668 °C, which is benefical for bulk single crystal growth. Experimental and theoretical calculation results indicate that Na4SrAs2S8 is a practically usable IR NLO crystal, also motivating the exploration of thioarsenates as high-performance IR NLO candidates.
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