Temperature and concentration quenching of Tb3+ emissions in Y4Al2O9 crystals

Spectroscopic properties of trivalent terbium (Tb3+) activated Y4Al2O9 (abbreviated YAM) crystals were studied. Concentration and temperature dependent emission spectra and fluorescence dynamics profiles have been investigated in YAM: Tb3+ in order to understand better processes responsible for quenching of the terbium D-5(3) and D-5(4) emissions. Decays were modelled using Inokuti-Hirayama approach to obtain information on the energy transfer mechanism. The cross-relaxation transfer rates were experimentally determined as a function of temperature and Tb3+ concentration. The investigation revealed strong influence of cross-relaxation process on D-5(3) emission quenching. The two different processes responsible for the increase of fluorescence quenching with growing temperature were observed, both related to thermal activation energy. For temperatures above 700 K, the temperature dependence of the emission intensity ratio (D-5(3)/D-5(4)) becomes linear and the decay times are rapidly decreasing monotonously with increasing temperature, what is confirming the potential of Y4Al2O9: Tb3+ material in high temperature luminescence thermometry. (C) 2012 Elsevier B.V. All rights reserved.