Spectroscopic properties of holmium ion in PbO–B₂O₃–SiO₂–Al₂O₃ glass system

The glasses of the composition 30PbO–60B₂O₃–5.5SiO₂–(4.5 − x) Al₂O₃–xHo₂O₃ (with x varied from 0 and 2 mol%) were prepared. Density (ρ), refractive index (n), and average molecular weight (M) were calculated from experimental measurements of these glasses. The spectra of optical absorption besides the photoluminescence were recorded at room temperature in the wavelength range of 300–2200 nm and 450–2200 nm, respectively. Using the optical absorption spectra the oscillator strengths were estimated and found to be in good agreement with the theoretical values evaluated using optical absorption spectra. Glasses doped with 0.5 mol% holmium had the highest bonding parameter, while those doped with 2.0 mol% holmium had the lowest. From this observation, it was concluded that holmium ions are in a more covalent environment in H₂₀ glasses. The overall analysis of the luminescence spectral results indicated maximal luminescence efficiency of the glasses with 0.5 mol%.