Synthesis and characterization of orthorhombic LiGaS ₂

In order to obtain pure and high-quality LiGaS ₂ polycrystalline material, a novel synthesis method from LiGa and S was proposed and compared with the direct synthesis method from elements. The vertical long tube quartz reactors were applied as the bottom of this reactor being the high temperature zone and the top of this reactor being the low temperature zone. The structure was characterized by the X-ray powder diffraction (XRD) and Raman spectra. The thermal behavior and optical property of samples were also studied by the simultaneous differential scanning calorimetry/thermogravimetric (TG-DTA) and ultraviolet visible diffuse reflectance spectra(UV-vis). The results show that the pure and high-quality LiGaS ₂ polycrystalline material can be obtained from the combinational method of LiGa and S. The effective force constants f _Li-S and f _Ga-S for Li-S and Ga-S interactions are determined to be 16.0 N/m and 39.6 N/m, respectively. The melting point of LiGaS ₂ is 1 020 °C and this material is stable under 1 100 °C. The ultraviolet absorption edges of white, yellow and grey samples are 323, 435 nm and 496 nm, respectively.