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

✍ Scribed by Prashant N. Kumta; Subhash H. Risbud

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 981 KB
• Volume: 18
• Category: Article
• ISSN: 0921-5107
• DOI: 10.1016/0921-5107(93)90141-9

✦ Synopsis

Lanthanum sulfide (La2S3) exhibits several different allotrophic forms, of which fl-La2S 3 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, fl-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 h result in the formation of fine ( ~-0.5-1.0 pm) fl-La2S 3 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.