Cathodoluminescence properties of yttrium aluminum garnet doped with Eu2+ and Eu3+ ions

摘要

Yttrium aluminium garnet (YAG) doped with Eu2+ and Eu3+ ions is very interesting as a phosphor for conversion of light-emitting diode light for white light sources. The europium ion occupies the structural position of yttrium in yttrium aluminium garnet and has valence state Eu3+. Our sample was doped with Zr4+, which is why some of the europium ions had valence state Eu2+. As a rule, luminescence of Eu3+ ions is observed in the orange and red range of spectrum. The luminescence of Eu2+ in yttrium aluminum garnet is characterized by an intensive broad band with maximum of intensity at about 560 nm (green color). In this work, we studied the intensity and decay time dependences on europium concentration, and the influence of excitation power density on the cathodoluminescence of the sample. The most interesting result is the change of visible cathodoluminescence color in dependence on the density of the exciting power.