Luminescence spectra and structure of Er3+ doped alkali borate and fluoroborate glasses

Abstract

Trivalent erbium (Er3+) ion doped alkali borate and fluoroborate glasses were prepared and their structural and spectroscopic properties have been studied through XRD, FTIR, optical absorption and luminescence spectral measurements. The FTIR spectral studies reveal the presence of BO3, BO4 structural units and the strong OH− bonds in the title glasses. The absorption spectra were used to determine the bonding parameters (β¯,δ) of the prepared glasses. Judd—Ofelt intensity parameters (Ωλ, λ=2, 4 and 6) have been calculated from the optical absorption spectra and are used to predict the important radiative properties like radiative transition probability (A), stimulated emission cross-section (σPE) and branching ratios (βR) for the excited state transitions such as 2H9/2→4I15/2 and 4S3/2→4I15/2 of the Er3+ ions in the prepared glasses. Optical band gap energy (Eopt) values through direct, indirect allowed transitions and the Urbach energy (ΔE) values of the prepared Er3+ glasses have also been determined and compared with similar studies. The spectral characteristics of the Er3+ ions due to compositional changes have been examined and reported in the present work.