Metamorphosis of the properties of the gas-phase fraction of ZnS:Mn obtained by the method of self-propagating high-temperature synthesis from the charge with a different Zn/S ratio

Performed in this work is a comparative analysis of photoluminescence, photoluminescence excitation and EPR spectra of gas-phase fraction of powdery ZnS:Mn obtained using the self-propagating high-temperature synthesis from the charge with a different Zn/S ratio. It was found that the size of particles in the synthesized materials was with in the range 10–300 nm. The size that is comparable with the Debye screening length (L). The luminescence and other characteristics of the studied material were found to differ significantly from the bulk ones. This finding has been explained by a unique energy structure of crystallites. Zn/S ratio has been shown to impact significantly on the crystallites sizes and the amount of incorporated Mn. The largest crystallite sizes and the high Mn content were observed in the powder synthesized with a stoichiometric Zn/S ratio, while the minimum particle sizes - in the powders synthesized with S excess. At sulfur excess, the size of particles is close to the Debye length, and carriers can freely migrate in the conduction band to the surface, where mainly nonradiative recombination occurs. The stoichiometric Zn/S ratio or Zn excess in the charge results in the increase of the particle sizes up to the values 2L ≤ d≤3L. Such materials are characterized by minimization of non-radiative losses. This finding opens new possibilities for ZnS application.