Temperature influence on NaLaF4:Er3+ green luminescence

Er3+ doped NaLaF4 is a promising material for up-conversion luminescence applications due to low phonon energy and multisite nature of the crystalline lattice. In this work, luminescence processes in NaLaF4:Er3+ materials have been studied at different temperatures. Spectra and decay kinetics of the green luminescence were measured under excitation to F-4(7/2) state. Analysis of the green luminescence excitation spectra, the luminescence spectra and the luminescence decay kinetics at different temperatures reveals that the observed single green luminescence spectra at room temperature are related to overlapping of the green luminescence excitation bands from erbium ions located at non-equivalent lattice sites. In addition, spectroscopic data obtained from the green and the infrared luminescence spectra at different temperatures suggest that both S-4(3/2) and H-2(11/2) states are involved in energy transfer between erbium ions, leading to concentration quenching of the green luminescence. (C) 2016 Elsevier B.V. All rights reserved.