Luminescence and phonon sideband analysis of Eu3+ doped alkali fluoroborate glasses for red emission applications

Abstract

Trivalent europium (Eu3+) doped alkali fluoroborate glasses (KBZFB) with molar composition 10K2O + 10BaO + 10ZnF2+(70 − x)B2O3 + xEu2O3 (x = 0.1, 1.0, 2 and 2.5 mol%) have been prepared by melt quenching technique. The structural aspects were explored through XRD, FTIR and Raman analyses. The spectroscopic properties were investigated using optical absorption, photoluminescence and decay curve analyses. Under 393 nm excitation, Eu3+ doped KBZFB glasses give intense red emission (612 nm) of Eu3+ ions corresponding to 5D0→7F2 transition. Judd–Ofelt theory has been employed to evaluate the phenomological intensity parameters. Radiative properties like radiative transition probabilities (A), radiative life time (τR) and branching ratios (βR) were also calculated. Phonon sidebands were observed in the excitation spectra on the high energy side of the pure electronic transition 7F0 → 5D2. The phonon energy (ℏω) and the electron–phonon coupling constant (g) were derived from the phonon sideband spectra. The luminescence decay was analyzed and the lifetime of the samples has been estimated. The experimental lifetime is compared with theoretical value and better quantum efficiency is obtained. The emission intensities were characterized using CIE chromaticity diagram and the prepared glasses offer pure intense red emission which is useful for various photonic applications.