Multicolor emission in [formula omitted] clusters and Eu3+ activated ZnO–P2O5 glasses achieved under near ultraviolet light excitation

Abstract

The structural and photoluminescence properties of zinc phosphate glasses activated with Agmn+ clusters and Eu3+ are studied. The addition of Ag+ and Eu3+ does not significantly modify the glassy structural properties evaluated by X-ray diffraction (XRD) patterns and Raman spectroscopy. The only change observed by Raman spectroscopy, is ascribed to the creation of molecular oxygen. The photoluminescence spectra, recorded under near ultraviolet (NUV) light excitation, display the feature broad band attributed to Agmn+ clusters. With the Eu3+ addition, Eu3+ bands located at 578, 591, 611, 652 and 701 nm, appear on the Agmn+ cluster emission, achieving the highest intensity at 0.8 mol% of Eu3+. This behavior is accompanied by a gradual reduction of the Agmn+ cluster emission. Sinks related to Eu3+ absorption on Agmn+ cluster emission and shortening of Agmn+ cluster: S1 → S0 and T1,T2 → S0 emission decays, suggest respectively the existence of radiative and non-radiative energy transfers from Agmn+ clusters to Eu3+. The Burstein model points out that the non-radiative energy transfer processes are predominantly mediated by electric dipole-dipole interaction for the Agmn+ :S1 → S0 transition. The emission tonality, estimated from the CIE1931 chromaticity coordinates and correlated color temperature (CCT) can be tuned from the cold white region to the warm white one, with effective quantum yield measurements up to 48%, depending on the excitation wavelength and Eu3+ doping content. Emission tonalites out of the white light region (orange-pink, purple-pink and pink) are obtained at higher amounts of Eu3+ (0.8 and 1.0 mol%) as well.