Eu -Activated Gd V O : Energy Transfer, Luminescence, and Temperature-Dependence Characteristics.

A new phosphor of the type Gd Eu V O (x=0-1.0) was synthesized through the solid-state reaction ceramics method. A pure phase formation was verified by using X-ray powder diffraction measurements. The luminescence of Gd V O :Eu was investigated through optical and laser excitation spectroscopy. The luminescence curves were investigated in the temperature region 10 to 300 K. Gd V O shows a self-activated luminescence under excitation with UV- and near-UV light. The spectra, the decay lifetimes, and the thermal stability of Gd Eu V O (x=0.005-1.0) strongly depend on both the Eu concentration and the temperature. The tunable luminescence is realized by controlling the Eu -doping level to adjust the host energy-transfer efficiency from the VO groups to the Eu activators. At low Eu concentrations (<30 mol %), the intensity and lifetime show an unusual change with an increase of the temperature from 10-300 K, that is, the luminescence experiences a straightforward enhancement. The energy transfer from the VO group to the Eu ions could be accelerated with an increase of the temperature resulting in an unusual enhancement of the Eu luminescence and lifetime. However, the emission of the Eu ions decreased for highly Eu-doped samples (>30 mol %) with an increase of the temperature. The luminescence mechanism was discussed on the basis of the charge-transfer band of the Eu ions, the doping concentration, and the proposed microstructures in the lattices.