Synthesis of binary and multinary metal sulphides by precipitation and their characterisation

•CuS, In2S3, CuInS2 and CuGaS2 are synthesised by precipitation using Na2S.•Powders acquire crystallinity on heat treatment at or above 473K.•Formation of ternary sulphides is accompanied with the evolution of SO2.•Powders have>90% phase purity with no significant Na contamination.•Band gap of CuS, In2S3, CuInS2 and CuGaS2 is ∼2, 2.3, 1.3 and 2.4eV respectively.