Enhancement of 5D0→7F2 red emission of Eu3+ incorporated in lead sodium phosphate glass matrix

Abstract

Characteristics of absorption energy bands and luminescence emissions of 1% Eu2O3 embedded in 10% PbO +40% Na2O + 49% P2O5 glass matrix have been reported here. The absorption spectra at room temperature have been recorded in the ultraviolet–visible region. We have assigned eight energy bands which occur due to the transition from the ground multiplet 7F0 as well as 7F1. Amongst them the strongest and sharp absorption peak is noticed at 393 nm corresponding to 7F0 → 5L6 transition. The excitation spectra show that the intensity of the 5L6 band is the strongest. Applying excitation at 393 nm, the luminescence emissions of the Eu3+ glass have been analyzed. Among seven emission peaks in the visible, the intense and most prominent emission is found at 612 nm in the red region due to 5D0→7F2 transition. The decay rates for this transition exhibits single exponential characteristics. The radiative parameters such as branching ratio (βm), effective bandwidth (Δλeff), luminescence intensity ratio R = (5D0 → 7F2)/(5D0 → 7F1), and decay lifetime (τm) are measured and compared with other similar host glasses. The color chromaticity coordinates of the emission are characterized by CIE1931 (Commission Internationale de l’Eclairage) diagram. Upon excitation at 393 nm in this glass the chromaticity coordinates are estimated as (0.634, 0.346) which show red emission. It reveals high color purity of 95.3% and correlated color temperature (CCT) value of 2180 K. The result of our present work indicates that the red light emission of Eu3+ is highly enhanced in lead sodium phosphate glass matrix in comparison to other host matrices reported in the literature.