Study on preparation and properties of Ba ²⁺ doped lanthanum sesquisulfide ceramics sintered by spark plasma sintering

γ-La ₂S ₃ polycrystalline ceramics were prepared by spark plasma sintering using γ-La ₂S ₃ powder as raw material synthesized by the gas-solid reaction. The effect of doping content of Ba ²⁺ on the phase composition of γ-La ₂S ₃ powder was studied. The influences of sintering temperature and resulfurization on the microstructures and infrared transmittance of γ-La ₂S ₃ polycrystalline were analyzed. The result indicated that γ-La ₂S ₃ phase could be stabilized well by doping Ba ²⁺ and pure γ-La ₂S ₃ phase could be obtained when n _La/n _Ba changed from 5 to 15. The polycrystalline ceramic sintered at 1150°C for 5 min exhibites high densities and uniform grain size, the maximum transmittance reached 42% in 10-14 μm after resulfurized in the CS ₂ atmosphere for 2.5 h.