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Non-aqueous chemical synthesis of tetragonal (β-La2S3) lanthanum sulfide powders

1993; Elsevier BV; Volume: 18; Issue: 3 Linguagem: Inglês

10.1016/0921-5107(93)90141-9

1873-4944

Prashant N. Kumta, Subhash H. Risbud,

Chalcogenide Semiconductor Thin Films

Lanthanum sulfide (La2S3) exhibits several different allotrophic forms, of which β-La2S3 is an intermediate polymorph that is stable at temperatures of 900 °C. It exhibits the tetragonal structure and could be a potential phosphor material. Traditionally, β-La2S3 has been synthesized using melt solidification and gas-solid reactions which require extended heat treatment cycles, invariably resulting in the formation of mixed phases. In this paper, low temperature non-aqueous chemical synthesis routes have been developed using inorganic and metallorganic starting materials to synthesize ultrafine (≈ 20 nm) sulfide precursors. The precursors on sulfidization at 1000 °C for 8 result in the formation of fine (≈0.5–1.0 μm) β-La2S3 particles. The physical, thermal, and microstructural chemistry of these precursors have been assessed using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron microscopy (SEM/TEM) with a view to understand the synthesis mechanism and the tetragonal phase formation.