AgGa0.6In0.4Se2 polycrystalline materials were synthesized by mechanical and temperature oscillation method in a two-layer quartz ampoule using high-purity elements according to the stoichiometry with an excess of 1% Se. The melting and freezing points of the materials were determined to be 804.3 ℃ and 775.6 ℃, respectively, through thermal analysis. A crack-free AgGa0.6In0.4Se2 crystal of Φ20 mm×60 mm was grown by modified vertical Bridgman method in a two-layer carbon coated quartz ampoule with specially designed seed pocket. The crystal was with chalcopyrite structure. The lattice constants of aand cwere 0.602 32 nm and 1.118 33 nm, respectively. The reflection faces and cleavage face were (112) faces. A wafer with 2 mm thickness was cut from the as-grown crystal. Its transmittance was up to or more than 60% in a range of 0.836~19.65 μm. Its calculated band gap was about 1.48 eV. The results proved that the grown crystal was of integral structure and high quality, and it can be used for fabrication of mid-far infrared nonlinear optical devices.
