Dependence of Eu3+ photoluminescence properties on structural transformations in diopside-based glass-ceramics
Résumé
Herein, diopside based glass-ceramics (GCs) were produced by sintering of glass powder compacts at 850 °C for 300 h. A special attention was paid on understanding the influence of structural transformations upon substituting strontium for calcium on the Eu3+ emission behavior. X-ray diffraction and Raman spectra showed the formation of diopside (CaMgSi2O6) in Sr-free glasses. Introduction of Sr led to the appearance of Sr-akermanite (Sr2MgSi2O7), whose formation increased continuously with increasing Sr/Ca ratio. The photoluminescence spectra exhibited intense 5D0 →7Fj transitions of Eu3+ ions. The intensity parameters (Ω2 and Ω4) and the Eu–O ligand behavior were determined using the Judd-Ofelt (JO) theory from the emission spectra as a function of various Sr concentrations. The as obtained JO intensity parameters Ω2 (5.31–5.21 pm2) and Ω4 (4.89–5.84 pm2) indicated the ligand behavior of the Eu–O bonds and a high asymmetrical and covalent environment around Eu3+ ions in the present host matrix. In comparison with other Eu3+-doped GCs, diopside based GCs containing high fraction of SrO exhibited adequate photoluminescence for optical lighting and display devices.