Synthesis and photoluminescent characteristics of yellow ZnS:Cu,Cl phosphor

Abstract

A yellow ZnS:Cu,Cl phosphor has been prepared using two firing steps. Firing ZnS in the presence of activator CuSO₄ and the flux BaCl₂, MgCl₂ and NaCl in the mole percentage ratio of 13.8: 39.9:46.2 at 1150°C for 5 h in N₂ atmosphere produces a wurtzite structure of the ZnS matrix with the particle size above 25 <i>μ</i>m<i>.</i> The phosphor shows photoluminescence emitting light at 540 nm, but does not show any electroluminescence property at this stage.

Second step firing at 750°C in the presence of CuSO₄ and MgCl₂, not only increases the photoluminescent brightness but also produces electroluminescence. The morphology of the ZnS matrix changes from wurtzite to sphalerite after second firing. Sphalerite structure for ZnS:Cu,Cl phosphor is essential for producing electroluminescence.