Comparing the luminescence processes of YVO4:Eu and core-shell YVO4@YF3 nanocrystals with bulk-YVO4:Eu

Comparative analysis of bulk, non-coated and core-shelled nanocrystalline YVO₄:Eu was performed by means of time-resolved luminescence and VUV excitation luminescence spectroscopy techniques. Nanocrystalline YVO₄:Eu samples – both as-prepared and YF₃ core-shelled – have been synthesized by means of a microwave-assisted synthesis in ionic liquids, which allows to obtain 10–12 nm nanoparticles with high crystallinity. The results show noticeable differences between bulk and nanocrystalline YVO₄:Eu in photoluminescence experimental data, which explains by influence of the nanocrystal surface. A YF₃ core-shell layer around YVO₄:Eu nanoparticles partially recovers the intensity of the Eu³⁺ emission. It is demonstrated that the Eu³⁺ luminescence recovery is achieved at the expense of the suppression of the intrinsic emission but not due to the passivation of surface loss centers in core-shelled nanocrystals. It is also shown that surface loss processes are the reason of the degradation of energy transfer efficiency from the host lattice to Eu³⁺ under high-energy excitations in vacuum ultraviolet spectral range.