Phonon sideband and Judd–Ofelt analyses of trivalent europium doped fluoroborosilicate glasses for red emitting device applications

Abstract

Present study reports the characterization of Eu3+ ions doped fluoroborosilicate glasses (FBSEU) with chemical composition 10BaO + 10ZnF2 + 10K2O + 20SiO2 + (50 − x) B2O3 + xEu2O3 (x = 0.1,0.5,1,1.5 and 2 mol%) synthesized using melt quenching technique. XRD and FTIR analyses were carried out to obtain the structural characteristics. Through Differential Scanning Calorimetry (DSC) analysis, the glass transition temperature (Tg) of the sample was determined. To study the luminescence properties and local structural evolution, absorption, photoluminescence emission and excitation spectra were recorded and analysed. For evaluating the Eu3+-ligand bond within the host, bonding parameter was calculated and is found to be covalent. The phonon energy of the prepared sample was calculated from PSB (phonon side band) spectrum and is obtained as 990 cm−1. The glasses show strong red emission via 5D0 → 7F2 transition with 392 nm excitation. Judd–Ofelt (JO) analysis was implemented using the emission spectra to assess the radiative properties such as radiative transition probabilities (A), radiative lifetime (τR), branching ratios (βR), etc. A higher branching ratio (64%) recommends the present glassy system for laser applications. The luminescent lifetime was calculated from the decay curve analysis (2.87 ms) and compared with theoretically predicted values (4.2 ms) using JO theory. Quantum efficiency of the sample was also determined experimentally and theoretically. The emission intensities were characterized using CIE chromaticity diagram and the FBSEU glasses gives red emission with excellent colour purity.