Optical and spectroscopic properties of Eu2O3 doped CaBAl glasses

Abstract

Eu2O3 doped CaBAL glasses (x Eu2O3) - (25-x) CaO - (50) B2O3 - (15) Al2O3 - (10) CaF2 (x=0, 5, 1, 2, 3, 4, 5, 10wt%) were prepared by using conventional melt-quenching and studied by means of density measurements, refractive index, optical absorption, luminescence and radiative lifetime. The results are discussed in terms of Eu2O3 content. The incorporation of Eu2O3 leads to an increase in the electronic polarizability and the refractive index. A linear increase with Eu2O3 content was observed in the optical absorption coefficient at 394nm. The luminescence spectra present typical Eu3+ emission and do not present quenching up to 10wt%. The luminescence ratio R/O I(5D0→7F2)/I(5D0→7F1) presents an increase with Eu2O3 doping; it indicates a reduction in local symmetry around the Eu3+ ions. The CIE 1931 diagram presents a red shift and an increase of color purity with Eu2O3 addition. The luminescence as a function of temperature shows an increase of 25% in the luminescence intensity for the Eu0.5 sample, at 592nm. The radiative lifetime at 614nm shows an exponential decay due to the reduction of the interionic distance Eu3+ - Eu3+ and the increase of the ion-ion interaction.