Effects of pressure on the emission of CaWO4:Eu3+ phosphor

•Pressure has great influence on the fluorescence intensity and the energy levels of CaWO4:Eu3+.•Raman experiments further confirm the scheelite to wolframite structure transformation.•The mechanism for the effects of pressure on the emission has been discussed.

CaWO4:Eu3+ (Ca0.925Eu0.05WO4) and CaWO4 phosphors were synthesized by solid state method. Here, the pressure effect on the photoluminescence of CaWO4:Eu3+ has been investigated with a diamond anvil cell up to 20 GPa at room temperature. It is observed that pressure has a great influence on the fluorescence intensity and the energy levels. With increasing pressure, the spectral features shift towards lower energies, and the 7F1 multiplet will split into three Stark levels due to the removal of the degeneracy by the crystal-field interaction. In addition, the emission intensity of the 5D0 → 7F1 transition decreases significantly. Raman experiments further confirm the scheelite to wolframite structure transformation presents at around 10 GPa. Upon release of pressure, this high-pressure phase transforms back to the original scheelite phase, and continuously remains stable to ambient conditions.