Abstract: BaGa4Se7 (BGSe) is currently attracting considerable attention as a new type of infrared nonlinear crystal. We explored the synthesis of BGSe polycrystalline raw materials using both the twotemperature zone method and the high-pressure-assisted method, and designed a rapid purification method with a large temperature gradient to purify the synthesized polycrystalline material firstly. And then, the phase composition and impurity concentration of BGSe polycrystals before and after purification were characterized using powder X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS) and energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction spectra are consistent with theoretical simulation results, showing no impurity peaks. ICP-MS test results also show a significant reduction in the content of metal impurities such as Fe, Al, and O impurity in the ingot after purification. The research can provide a raw material basis for the growth of high-quality single crystal.

Key words: material, polycrystalline synthesis, two-temperature zone method, high-pressure-assisted method, large temperature gradient purification, infrared nonlinear crystal