Analysis of the Influence of the Structure of ZnS:Cu,Br Phosphors on Luminescent Characteristics Using Percolation Theory

During the synthesis of ZnS:Cu,Br phosphors (zinc sulfide activated by copper and bromine ions), a composite wurtzite–sphalerite structure is formed, and the luminescence intensity and the content of luminescence centers in the form of donor–acceptor pairs of Cu_Zn–Br_S reach a maximum at a certain proportion of the wurtzite phase in the phosphor. This is confirmed by the study of the phase composition of the synthesized phosphors and changes in the radioluminescence spectra. The observed result is proposed to be explained using the concepts of percolation theory, taking into account that the formation of a luminophore matrix of a composite wurtzite–sphalerite composition promotes an increase in the diffusion rate of the activator and coactivator ions (Cu⁺ and Br^–) along the interphase boundary and the formation of glow centers. It is shown that radiation exposure, which promotes the formation of structural defects in the initial ZnS matrix, additionally increases the luminescence intensity. The use of this approach allows the creation of materials with the optimal nanostructure and high target characteristics.