4 research outputs found
The factors influencing luminescent properties of ZnS:Mn obtained by the method of one-stage synthesis
Considered in this paper is the model that combines appearance of defects
responsible for self-activated (SA) emission in ZnS with its piezoelectric properties.
Being based on analysis of the luminescence spectrum, the authors demonstrate the
influence of mechanical destruction, impact of ultrasound, microwave radiation and
pulsed magnetic field on the emission efficiency for centers of luminescence connected
with intrinsic defects in ZnS:Mn prepared using the method of self-propagating hightemperature
synthesis (SHS). It has been shown that downsizing the ZnS:Mn crystals
prepared according to the above method as well as more discrete differentiation of phases
present in this material due to development and growth of inner boundaries and surface
under external actions leads to quenched SA-photoluminescence with λ ~ 400–525 n
Electroluminescence powdered ZnS:Cu obtained by one-stage synthesis
Photo- and electroluminescence properties of ZnS obtained using selfpropagating high-temperature synthesis and doped with Cu were studied in this work. It has been shown that high-temperature one-stage synthesis enables to obtain two-phase system ZnS-Cu₂₋xS with the maximum radiation 515 nm for photo- and electroluminescence. Since the synthesis process is non-equilibrium, impurities distribute nonuniformly in the bulk of microcrystals. Additional annealing and introducing the Ga coactivator lead to more non-uniform distribution of impurities in the bulk of microcrystals. It causes the increase in the intensity of the blue band in photoluminescence spectra and shift of the maximum of electroluminescence toward longer wavelengths. It is probable that this increase in the intensity of the blue band in photoluminescence spectra is caused by formation of the radiative centers Cui₋CuZn
Effect of heating rate on oxidation process of fine-dispersed ZnS:Mn obtained by SHS
The influence of annealing at 350 °C in air atmosphere on the luminescent characteristics of powdered ZnS: Mn obtained by self-propagating high-temperature synthesis has been studied. It was shown that variation in material heating rate due to changes in the annealing temperature results in different behavior of oxidative processes. It has been ascertained that the slow heating of powdered ZnS:Mn, compared with the rapid one in the presence of oxygen, promotes active oxidation of ZnS and formation of Frenkel pairs, increases mileage of defects acting as sensitizers, and their localization near Mn²⁺. The model which explains the observed changes in the luminescence and PLE spectra has been presented