Influence of preparative conditions for obtaining ZnS:Mn nanoparticles using ultrasound-assisted precipitation

Nanocrystalline manganese-doped zinc sulphide (ZnS:Mn) phosphor powders were prepared by ultrasound-assisted precipitation, using the simultaneous addition of reagents under controlled constant flow. The precipitation process was optimised at low temperature (40 °C), using variable concentrations of reagents, with or without diheptyl sodium sulphosuccinate as surfactant. Complementary investigations such as thermal analysis, X-ray diffraction, SEM, TEM and BET were used to characterise the phosphors. Photoluminescence spectra show a strong orange emission with a maximum centred at 590 nm due to the electronic transitions of Mn2+ ions occupying Zn2+ sites in the host lattice. Correlation of preparative conditions with morphostructural and luminescent characteristics enables us to determine the optimal conditions for the preparation of ZnS:Mn nanoparticles with crystallite size in the range of 1.4–2.8 nm. ZnS:Mn nanopowder with nanoparticle size of ~ 2.5 nm, precipitated from diluted reactant solution in the presence of 5.0 g/L of diheptyl sodium sulphosuccinate, displays the highest photoluminescence.