Structural characterization of chemically synthesized cubic lanthanum sulphide (γ-La2S3)

Cubic lanthanum sulphide (γ-La2S3) belongs to the family of rare-earth chalcogenides and is a potential far-infrared (8-14 μm) transmitting material. Low-temperature chemical techniaues incorporating organometallics have been employed to synthesize ultrafine sulphide precursors (about 20 nm in size) at room temperature. The precursors transform to form cubic (γ-La2S3) powders at 1000°C. The thermal stability, phase evolution characteristics and microstructure of the fine particles have been investigated using differential scanning calorimetry, X-ray diffraction and electron microscopy. Convergent-beam electron diffraction was performed on the crystalline powders and hot-pressed ceramics and the space group was identified to be 143d.