Photoluminescence of ZnS:Tb phosphors fritted with different fluxes

ZnS:Tb phosphor powders were prepared by solid-state synthesis. Without addition of flux, only emission from the host luminescence was observed. There is no the characteristic luminescence of Tb for ZnS:Tb without the additions of fluoride fluxes or chloride fluxes. For ZnS:Tb with LiF, NaF and KF additions, characteristic luminescence of Tb emerges, which corresponds to the transitions of 5D4 → 7FJ. The highest peak is located at 548 nm. For ZnS:Tb with additions of NaCl and KCl fluxes, both the characteristic luminescence of Tb and the luminescence of the host material were observed. However, only the host luminescence was shown in the spectrum for ZnS:Tb fritted with LiCl. It is difficult to observe the characteristic luminescence of Tb. The microstructure of ZnS:Tb fritted with chlorine fluxes show well crystallized uniform grains. However, with fluoride fluxes, huge crystalline grains with irregular morphology were obtained.