STRUCTURAL AND OPTICAL CHARACTERISTICS OF Eu2+ IONS IN SODIUM-LEAD-ZINC-LITHIUM-BORATE GLASS SYSTEM

Structural and optical properties of Eu3+-doped sodium-lead-zinc-lithium-borate glasses (65−x)B2O315Na2O10PbO5ZnO5Li2OxEu2O3 (where x = 0, 0.05, 0.1, 0.5, 1.0, 2.0 and 4.0) have been measured and analyzed by varying the Eu3+ ion concentrations. The physical parameters such as polaron radius, field strength and inter nuclear distance have been determined from measurements of densities and refractive indices. The structural properties of the prepared borate glasses were analyzed based on X-ray diffraction (XRD) and FTIR instruments. The diffraction spectra show no characteristic peaks in these glasses, which indicates the amorphous nature of the glasses. The infrared spectrum of the Eu3+-doped sodium-lead-zinc-lithium-borate glass systems show three disparate regions for active absorption band around 830–860 cm−1, 1020–1040 cm−1 and 1170–1180 cm−1. The electronic transitions in the UV–vis and NIR regions are assigned to the 7F0 → 5D4, 7F0 → 5G2, 7F0 → 5L6, 7F0 → 5D3, 7F0 → 5D2, 7F0 → 5D1, 7F0 → 5D07F1 → 5D07F0 → 7F6 and 7F1 → 7F6 levels centered at 362 nm, 380 nm, 395 nm, 414 nm, 465 nm, 533 nm, 583 nm, 590 nm 2092 nm and 2202 nm respectively. Five transition bands of luminescence spectra have been observed by using an excited wavelength of 395 nm. The luminescence intensity ratio (R) of 5D0 → 7F2 (electric dipole) transition to 5D0 → 7F1 (magnetic dipole) transition has been determined to obtain the strength of the covalent/ionic bond between the Eu3+ ions and the surrounding ligands. Radiative life time and emission color of the glasses were estimated and compared with other literature data by varying Eu3+ concentrations. The experimental lifetime of the 5D0 level was found to increase with increasing Eu3+ ion content, suggesting higher non-radiative energy transfer among Eu3+ ions in the glasses.