LAUSR

Abstract A series of Bi2O3:Ho3+ (0.2–5 mol% Ho) phosphors with a crystalline monoclinic phase was synthesized using a co-precipitation route. The particle morphology and size were determined using a field emission scanning electron microscope (FESEM). The FESEM showed that the synthesized material consisted of needle-like particles. The oxidation state of the Bi as well as oxygen vacancies were investigated using X-ray photoelectron spectroscopy. It was found that Bi3+ was the dominant oxidation state in the samples, although Bi2+ was also detected. The doped Bi2O3 revealed a decrease in bandgap with an increase in Ho3+ concentration. The photoluminescence (PL) revealed that Ho3+ was the emitting centre in the samples. The 5F4/5S2→5I8 transition was responsible for the most intense emission in the visible region, whereas the near infrared emissions resulted from the 5S2→5I6, 5I6→5I8 and 5S2→5I5 transitions. A superior catalytic activity and a high PL intensity were observed due to the presence of a higher number of oxygen vacancies and defects. The 4 mol% Ho3+ doped sample was found to have the optimum doping concentration for both the PL intensity and photocatalysis activity. The results revealed that Bi2O3:Ho3+ can be potentially used for solid state displays as well as a photocatalyst under UV–visible light exposure.