Optical characteristics of Eu3+ doped alumino borophosphate glass containing Al3+, Zn2+, Li2+, Sr2+ and Ba2+ ions

Europium (Eu3+) doped alumino borophosphate glass (ABP) containing Al3+, Zn2+, Li2+, Sr2+, and Ba2+ was formed by melt quenching method. FT-IR spectroscopy in the range 400–4000 cm−1 was used to describe the vibrational spectrum of the glass sample in order to define the various structural units. The optical absorption spectra of the glass revealed two weak bands due to 7F0 → 5L6 and 7F0 → 5D2 transition of Eu3+ in the UV–Vis range. The direct and indirect band-gap energies were calculated using Tauc's plot. The refractive index (n) of the prepared glass medium was measured to be decreases as the wavelength increases, and it is varying from 2.25 to 2.07 over the visible region. A photoluminescence spectrum was obtained on non-irradiated glass sample, and the spectra analysis indicated emission peaks (at 593 nm, 615 nm, 653 nm and 703 nm) attributable to the presence of Eu3+. The photo-luminescence decay profile of 5D0 → 7F2 (614 nm) of Eu3+ was also performed to investigate the effect of excitation wavelengths. The luminescence colours of the prepared glass sample were entirely fall on red region (x = 0.648 and y = 0.336) with the dominant wavelength 610 nm in the CIE 1931 chromaticity map. Using CIE chromaticity coordinates, the excitation purity (Pe), colour purity (Pcolour), colorimetric purity (Pcol) and Colour correlated temperature (CCT) were also evaluated. After irradiating the glass with γ-rays at a dosage of 2 kGy, the structural changes caused by the reduction of Eu3+ into Eu2+ ion in the glass matrix was examined using the EPR spectrum as well as its thermo-luminescence characteristics was also studied in the temperature range 300–650 K. The glow curve could be well defined as a superposition of five peaks in the temperature range, and the peaks were explained by second-order kinetics.