Judd–Ofelt analysis and physical properties of erbium modified cadmium lithium gadolinium silicate glasses

Erbium doped 50SiO₂ -30Li₂O- 1Gd₂O₃- (19 − x) CdO and x Er₂O₃ glass system, where (0 ≤ x ≥ 2.5), mol%, has been prepared by the conventional melt quenching technique. The physical, structural and optical properties are explained by analyzing the data obtained from X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–Visible (UV–Vis-NIR) and photoluminescence results. X-ray powder diffraction patterns show broad peaks which conform glassy nature of the sample. FTIR spectroscopy reveals the presence of SiO₄, CdO₄ and Er–O vibration groups in the glass samples. The optical absorption spectra in the wavelength range of 200–2500 nm were measured and the optical band gaps, Urbach energy, Electronegativity (χ) Electron Polarizability (α°), and Optical basicity (˄) were determined. The optical absorption spectra of Er³⁺ ions in these glasses show eleven bands and are assigned to the transitions from ground state to excited levels. It was found that the optical band gap increases from 3.19 to 3.51 eV with the increase in Er₂O₃ concentration. The strong sharp peak belongs to Er⁺³ emission is investigated in photoluminescence spectra at ordinary condition (1 atm. and at room temperature). It excites by wavelength of 385 nm and gives pale green color at 559 nm. Judd–Ofelt theory has been used to analyze the spectra arising from erbium ions doped 50 SiO₂ -30 Li₂O- 1Gd₂O₃- (19 − x) CdO and x Er₂O₃. The intensity parameters Ω_2,4,6 of the present complex and lifetimes of selected levels are theoretically calculated as well.