Site symmetry dependence on luminescence emission of Y2O3:Eu3+ dispersed in silica matrix

Abstract

ABSTRACT Lanthanide ion (Ln3+) doped Y2O3 materials are used in making display devices. Ln3+ ions can occupy C2 and S6 sites in Y2O3. In many reported papers, Ln3+ ions occupy more C2 site leading to enhanced luminescence intensity of electric dipole transition as compared to that of magnetic dipole transition. In this study, we have prepared Eu3+ ion doped Y2O3 particles dispersed in silica (SiO2) using urea hydrolysis at 165°C. Among the prepared samples lower heated sample show cubic phase Y2O3 wherease 1400oC show α-Y2Si2O7 and all the samples show the luminescence characteristics of Eu3+. In Y2O3:Eu-SiO2, the as-prepared, 500 and 900°C heated samples show the higher luminescence intensity for the electric dipole transition than that of magnetic dipole transition and it is opposite upon annealed at 1400°C. It confirms that Eu3+ ions in as-prepared, 500 and 900°C heated samples occupy C2 site (asymmetric environment), whereas in 1400°C heated sample, they occupy the S6 site (symmetric environment). However, microparticles of the Y2O3:Eu sample annealed at 1400°C show that Eu3+ ions occupy more C2 site as compared to the S6 site. This study suggests that occupancy of C2 and S6 sites in Y2O3 by Eu3+ ions can be varied by surrounding medium as well as heat-treatment temperature.