Defects and symmetry influence on visible emission of Bi3+ Co-doped CeO2: Eu3+ phosphor

A new red phosphor, Bi3+ co-doped CeO2:Eu3+, was synthesized by a hydrothermal co-precipitation method. XRD, TEM, Raman, XPS, luminescence spectra, energy transfer mechanism, and the decay time of Bi3+ co-doped CeO2:Eu3+ phosphor were systematically investigated in detail. Influence of Bi3- substitutions on Eu3+ surroundings and associated luminescence performance was researched. It is found that co-doping of Bi3+ promoted the increase of oxygen vacancies in the lattice. In addition, Bi3+-doped CeO2 deviates the known strongly dependency of oxygen vacancies defect association energy, and Bi3+ tend to interact with oxygen vacancies at the nearest-neighbor position to inhibit the defect formation of Ce3+ oxidation states. Therefore, the presence of Bi3+ effectively enhance the emission intensity of Eu3+ under the excitation at 365 nm, even when oxygen vacancies in the lattice are increased. The results indicate that, Bi3+ co-doping effectively increases oxygen vacancies and enhances the luminescence intensity of CeO2:Eu3+, which promotes its potential applications in biology and medicine.