White luminescence and energy transfer studies in Tb3+-Eu3+ co-doped phosphate glasses

Abstract

Europium and Terbium co-doped phosphate glasses with a chemical composition of 80NaH2PO4–18Na2CO3–2Al2O3, which have been named PNA, were well produced with melt-quenching technique. We studied the structural and optical properties of the material. According to the XRD pattern, all the samples have an amorphous structure. After adding Tb3+, it was revealed that the photoluminescence (PL) intensity of the 5D0 →7F2 transition increased. It was observed that the Tb3+ ion functions as a sensitizer for the Eu3+ ion, and significantly enhances the spectroscopic features of Eu-doped PNA. We demonstrated the possibility of excitation transfer from Tb3+ to Eu3+. The radiative lifetime (τR) calculated from Judd-Ofelt (J-O) theory, and the, empirically discovered, measured lifetimes (τmes) were compared for Eu-doped PNA and (Eu; Tb) co-doped PNA. The results reveal that the quantum efficiency (η) was found to increase after adding Tb3+ from 87 to 94% for the 5D0 →7F2 transition. The energy transfer was identified and explained both experimentally using the excitation and emission spectra and theoretically using the J-O theory. The results of the CIE chromaticity coordinates of (Eu, Tb) co-doped PNA were found in the white region, which suggests a significant promise in field emission displays.