XAFS analysis and luminescent properties of ZnS:Mn2+ nanoparticles and nanorods with cubic and hexagonal structure

ZnS:Mn2+ nanocrystals (NCs) were synthesized by a simple solvothermal method at 180 °C in different solvents. The NCs prepared in ethanol yielded cubic nanoparticles (NPs) with diameters of 10-15 nm. The NCs prepared in ethylenediamine and water (1:1 in volume ratio) yielded hexagonal nanorods (NRs) with diameters of 8-10 nm. X-ray absorption fine structure (XAFS) measurements were carried out to probe the local environment surrounding the Mn ions in the NPs and the NRs. The results showed that Mn ions were incorporated into the ZnS lattice substituting the Zn sites. The yellow-orange emission from the Mn2+4T1-6A1 transition was observed, its intensity relative to the blue-green emission increased from NPs to NRs. The surface effect was the main factor affecting the thermal and optical stability of NCs. The fluorescence lifetime of the Mn2+ emission for the NPs and NRs was 0.662 and 0.224 ms, respectively.