Enhancement of green emission from Tb3+: GdOBr phosphors with Ce3+ ion co-doping

A strong green emission ((D4 -->F5)-D-5-F-7) has been observed from Tb3+ (1 .0 mol%) doped into GdOBr powder phosphors upon excitation with an UV-wavel ength (226 nm). To this phosphor, different amounts of Ce3+ (from 0.1 to 1. 5 mol%) have been added to further improve the green emission efficiency of Tb3+-doped GdOBr. It has been found that the optimum concentration, 0.2 mo l% of Ce3+ results in a twofold enhancement of the green emission intensity . The green emission from Tb3+ could not be increased at higher Ce3+ concen trations due to the Ce3+-Ce3+ ion interactions, i.e., the concentration que nching effect. The mechanism involved in the energy transfer between the Ce 3+ and Tb3+ has been explained with an energy level diagram. (C) 2001 Elsev ier Science Ltd. Al rights reserved.