Luminescence properties of Eu, RE³⁺ (RE = Dy, Sm, Tb) co-doped oxyfluoride glasses and glass–ceramics

Eu, RE³⁺ (RE = Dy, Sm, Tb) co-doped SiO₂–CaF₂–Al₂O₃–CaO oxyfluoride glasses have been prepared by the melt quenching method. By heating the precursor glasses at 670 °C for 1 h, glass–ceramics containing CaF₂ nanocrystallites were obtained. DTA and XRD measurements were performed. Excitation spectra of the prepared samples as well as photoluminescence spectra at the excitation of 355 nm and 450 nm were measured, CIE colour coordinates and colour rendering indexes were found. In the glass–ceramics the presence of Eu²⁺ ions was observed by a broad emission band in the 400–500 nm spectral range. The most promising doping combinations for white light luminophores within our research are europium–dysprosium and europium–terbium, which allow obtaining white light both in glasses and glass–ceramics under 355 nm excitation. Heat treatment of glasses can be considered as a tuning mechanism to obtain white light because of the heat treatment dependent Eu²⁺ emission.