Effects of the host lattice and doping concentration on the colour of Tb3+cation emission in Y2O2S:Tb3+ and Gd2O2S:Tb3+ nanometer sized phosphor particles

Abstract

Y₂O₂S and Gd₂O₂S phosphor lattices activated with a range of Tb³⁺ concentrations have been successfully prepared as nanoparticles and their emission properties have been characterized using SEM, XRPD, photoluminescence spectroscopy and cathodoluminescence. ⁵D₃–⁵D₄ cross relaxation processes between Tb³⁺ cations were observed in both Y₂O₂S and Gd₂O₂S as a function of Tb³⁺ concentration. In the Y₂O₂S host lattice, the predominant emission colour shifts from blue to green with increased Tb³⁺ concentration. In contrast, green emission is always predominant in Gd₂O₂S at Tb³⁺ concentrations from 0.1 mol% to 5 mol%. This finding is explained in accordance with previous reports on the bulk materials that found the Gd₂O₂S lattice has a lower charge transfer state than the Y₂O₂S host lattice.