Crystallization of Ag Nanoparticles in Borate–Bismuth Glass and Its Influence on Eu3+ Luminescence

The aim of this study was to investigate the possibility of Ag nanoparticle crystallization in B2O3–Bi2O3 glass using a heat treatment method and to investigate the possible influence of the obtained nanoparticles on the emission intensity of Eu3+ ions. Borate–bismuth glasses with different B2O3:Bi2O3 molar ratios of 50:50, 60:40 and 70:50 with Ag and Eu3+ ions were successfully synthesized. The structure of the glasses was studied using XRD and FTIR methods. The XRD results exhibited a characteristic amorphous halo, confirming the absence of long-range order in the samples. The glass transition temperatures of various compositions, required to select the annealing temperature, were measured using DTA analysis. The strong maximum in the UV–Vis spectrum of the sample with the highest Bi2O3 content clearly indicated the presence of Ag nanoparticles in the glass. Moreover, a color change was observed for this sample, from slightly yellow to red. The presence of Ag nanoparticles was further confirmed via TEM and XPS studies. However, with a high content of Ag nanoparticles in the matrix, their positive effect on luminescence intensity was not observed. The obtained results show that B2O3–Bi2O3 glass and glass ceramics, with Ag nanoparticles and rare-earth (Re) ions, could be considered as a new phosphor for light-emitting diodes (LEDs).