Spectral characterisation of Sm3+ ions doped Oxy-fluoroborate glasses for visible orange luminescent applications

Abstract

Oxy-fluoroborate (OFB) glasses doped with different concentrations of Sm3+ ions have been prepared using conventional melt quenching technique and characterised for their lasing potentialities using spectroscopic techniques such as FTIR, optical absorption, emission and emission decay measurements. The FTIR spectrum has been recorded to determine the various functional groups present in the OFB base glass. From the absorption spectra, the bonding parameters (δ) were evaluated to find the bonding nature present between Sm3+ ions with its neighbouring ligands. The Judd–Ofelt intensity (J–O) parameters (Ωλ, where λ=2, 4, and 6), measured from the experimental oscillator strengths of the absorption spectral futures, are used to evaluate the radiative parameters for the fluorescent transitions 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 of Sm3+ ions in OFB glasses. The asymmetric ratio has been evaluated to understand the local disorder of Sm3+ ions in the glass network. The experimental lifetimes (τexp) measured from the decay curves are coupled with radiative lifetimes (τrad) to measure quantum efficiency (η) of the prepared glasses. The experimental lifetimes (τexp) for 4G5/2 emission state decrease with increase in Sm3+ ion concentration due to energy transfer. In order to elucidate the nature of energy transfer mechanism, the non-exponential decay curves are well fitted to the Inokuti–Hirayama model for S=6, which indicates that the energy transfer mechanism is of dipole–dipole type. The branching ratio (βR), stimulated emission cross-section (σse) and quantum efficiency (η) values measured for the most intense emission transition 4G5/2→6H7/2 (598nm) optimise the concentration of Sm3+ ions as 1mol% to produce bright visible orange lasing emission from these OFB glasses.