Heat-treatment-induced luminescence degradation in Tb3+-doped CePO4 nanorods

CePO4:Tb nanorods were synthesized via a simple wet-chemical route. The as-synthesized CePO4:Tb nanorods present high photoluminescence efficiency due to an efficient energy transfer form Ce3+ to Tb3+. However, heat treatment at 150 °C in air leads to a significant decrease of photoluminescence. X-ray photoelectron spectroscopy and excitation spectra revealed the oxidation of Ce3+ to Ce4+ in the heat-treatment process, which should be responsible for significant photoluminescence degradation due to the breakage of Ce3+→Tb3+ energy transfer. This conclusion is further supported by atmosphere and size effects of photoluminescence of CePO4:Tb under the heat treatment.