From Structure to Luminescent Properties of BO-BiO-SrF Glass and Glass-Ceramics Doped with Eu Ions.

Glass-ceramics with the composition BO-BiO-SrF were synthesized by the conventional melt-quenching technique and subsequent crystallization of the parental glasses. The temperature at which the ceramization was carried out was selected based on differential scanning calorimetry (DSC) analysis. The structure of the studied materials and the formation of SrF nanocrystals were confirmed by the Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. It was found that the amount of strontium fluoride introduced into the parental borate-bismuth glass has a significant impact on the growth of SrF nanocrystals. In particular, the influence of the crystalline SrF phase on luminescence intensity and kinetics was studied using EuO-doped samples. An increase in luminescence intensity was observed in the samples in which SrF nanocrystals were formed. This is most likely related to the fact that some of the Eu ions were (after annealing of the glass) located in the crystalline structure of strontium fluoride. This was confirmed both by the luminescence lifetime obtained based on the luminescence decay curves and the calculated Judd-Ofelt parameters, Ω and Ω. The results achieved confirm that the glasses and glass-ceramics described in this work could be considered as a new phosphor for light-emitting diodes (LEDs).