Spectroscopic investigation and local structure of Eu3+ ions in lead phosphate glasses for optical device applications

Abstract

Phosphate-based glasses are promising materials which are being employed for broad range of applications whereas Eu3+ is an efficient activator due to its predominant 5D0 →7F2 emission (red region). In this direction, an attempt has been made to investigate the effect of Eu3+ ions doped lead phosphate glasses (PPbKANEu: P2O5+PbO+K2O+Al2O3+Na2O+Eu2O3) to explore possible photonic device applications. Optical absorption, excitation, photoluminescence and decay rates are used to characterize the PPbKANEu glasses. The photoluminescence spectrum of Eu3+:PPbKAN glasses exhibit emission channels from the first excited (5D0) to the ground (7FJ (J =0–4)) multiplets. To determine the local site symmetry of surrounding Eu3+ ions, the relative fluorescence intensity ratio of 5D0→7F1 versus 5D0→7F2 emission channels has been analyzed. The emission spectrum of PPbKANEu glasses exhibits a comprehensive lifting of degeneracy of 5D0→7F2 and 5D0→7F1 emission channels. By considering C2v symmetry for Eu3+ ions, the second (B02= −406 and B22=−158) and fourth (B04=980, B24=297 and B44=926 cm–1) rank crystal–field (CF) characteristics were estimated along with CF strength factor (S= 402 cm–1). The lifetime of 5D0 state is estimated to be 2.09, 2.23, 2.21 and 2.21 ms for 0.1, 0.5, 1.0 and 2.0 mol% of Eu3+ ions, respectively. The analysis of the decay times reveals that the lifetime of 5D0 state is less affected by the concentration of the Eu3+ ion. The results are compared and discussed with reported values and confirm the potentiality of the PPbKANEu glasses for optical device applications in visible regions.