Preparation of ZnS and SnS Nanopowders by Modified SILAR Technique

Abstract

Nanocrystalline powders of zinc sulphide (ZnS) and tin sulphide (SnS) were prepared by modified SILAR (successive ion layer adsorption and reaction) technique. The technique involves multiple dipping of a substrate in cationic and anionic precursors. All the synthesized powders were found to contain nanocrytsalline grains. Broad humps at 26.9o for ZnS and 31.55o for SnS were observed in XRD patterns. The corresponding reflection plane was (101) in both cases. The presence of broad humps (large FWHM) confirms the presence of nanocrystalline grains. The particle size estimated using X-ray line broadening method was ~1.6 nm for ZnS and ~1.4 nm for SnS. However, instrumental broadening and strain broadening was not taken into account during particle size estimation. Large shift in bandgap energy values were observed compared to bulk values of the materials indicating quantum confinement. The bandgap energies were 4.08 eV for ZnS and 1.32 eV for SnS.