Effect of Ba2+ doping on the photoluminescence of YVO4: Eu3+ phosphor and first principles calculations

In this work, YVO4: Eu3+ phosphors with and without Ba2+ doping (having the formula of Y1-x-y (EuxBay)VO4) were prepared by the high-temperature solid-state reaction method, and their photoluminescence and relevant physical mechanism were studied. A large enhancement in the photoluminescence of the YVO4: Eu3+ phosphors by Ba2+ doping has been observed. When the Ba2+ doping concentration is at 3 at%, the YVO4: Eu3+ phosphors have the strongest photoluminescence. It has been found that the Ba2+ doping extends the luminescence decay lifetimes of YVO4: Eu3+. In addition, the Ba2+ doping also makes the charge transfer state absorption band of VO43− blue shifted and widens the 5D0→7F2 emission of Eu3+. The underlying mechanism for these results has been investigated using the first principles calculations. It has been shown that the Ba2+ doping increases the bandgap value of YVO4 and causes the energy level of the Eu-d orbit to split, and the individual atomic orbitals move toward higher energy after Ba2+ doping. A higher energy transfer efficiency from VO43− to Eu3+ has been predicted by the first principles calculations. The theoretical calculation results explain the photoluminescence enhancement of YVO4: Eu3+ by Ba2+ doping, and the mechanism has been revealed.