Preparation and photoluminescent properties of zinc oxide phosphor

ZnO green phosphors have been prepared by thermal oxidation of zinc sulfide under the assistant of ammonium chloride in air atmosphere. Their emission spectra under excitation wavelength at 350 nm show only one green emission peak at around 510 nm. However, the luminescence intensity and excitation peak position of ZnO phosphors are observed to vary significantly with oxidation temperature. The promotion of ammonium chloride for the green emission is explained by the participating of chloride in the replacement process of sulfur by oxygen due to its similar ion radius (rCl-=1.81Å) to that of sulfur ion (rS2-=1.84Å), which is beneficial to the formation of defects including interstitial zinc and oxygen vacancies.