Luminescence properties of Eu3+‐ and Tb3+‐doped δ‐Bi2O3 stabilized by Th4+ substitution

Abstract

AbstractThe extent of incorporating Eu3+ and Tb3+ for bismuth in the oxygen‐deficient fluorite structured Bi0.50Th0.50Oy has been examined together with the comprehension of their luminescence characteristics. The samples were synthesized by solution combustion method from which doping limits of Eu3+ and Tb3+, respectively, in the fluorite structure was determined. Uniform distribution of constituent elements was confirmed from elemental mapping. Doping Eu3+ and Tb3+‐ions introduced compressive strain and oxygen vacancies in the system. Raman spectra of doped samples confirmed the fluorite structure and revealed the existence of oxygen vacancies in them. While Tb‐doped samples showed a systematic decrease in band gap with increase in dopant concentration, such systematic variation was not observed for Eu‐doped samples. Conclusions about the local site symmetry around Eu3+ and Tb3+ ions in the defect fluorite structure have been drawn from the photoluminescent spectral analysis of doped samples. Energy transfer from Bi3+ to Eu3+ and Tb3+‐has been observed in these samples. The Judd‐Ofelt analysis has been carried out to understand luminescence characteristics in these samples.