Preparation of γ-La₂S₃ polycrystalline pellet by doping Ca²⁺

γ-La₂S₃ polycrystalline pellet were prepared by hot pressing method with the γ-La₂S₃ powder synthesized by the gas-solid reaction. The phase of powders with different dopant concentration of Ca²⁺ was studied. The effect of sintering temperature and sintering time on the infrared transmittance of polycrystalline pellet were analyzed. The result show that the addition of Ca²⁺ is beneficial to obtain stable γ-La₂S₃ phase. A high purity single phase γ-La₂S₃ with the Ca/La ratio of 1:5-1:15 was obtained. The polycrystalline pellet exhibites uniform grain size and relatively higher density, the maximum infrared transmittance is approximately 40% at wavelength of 10-14 μm after sintering at 1100°C for 1 h.