Effects of Ni2+ concentration and vacuum annealing on structure, morphology and optical properties of Ni doped ZnS nanopowders synthesized by hydrothermal method

Ni doped ZnS nanopowders were synthesized by hydrothermal method. The as-synthesized ZnS nanopowders possessed zinc blende structure with the particle sizes of ∼20 nm, and they display a broad emission band from 400 nm to 700 nm centered at ∼540 nm. The influence of Ni 2+ doping and vacuum annealing on the structure, morphology and optical properties was investigated systematically. The results revealed that the emission peaks are blue shifted with Ni 2+ doping, and the emission peaks of 0.2, 0.4, 0.6, 0.8 and 1.0 mol% Ni 2+ doped ZnS nanopowders are centered at ∼520, ∼ 510, 500, 490 and 470 nm, respectively. While, the zinc blende phase transformed to wurtzite phase when annealing at 600 °C or higher, and the annealed samples exhibited three emission peaks positioned at ∼490, ∼547 and ∼580 nm. The results indicated that the as prepared Ni 2+ -doped ZnS nanopowders have a potential application in LED as light conversion layer.