The Influence of Defects on the Luminescence of Trivalent Terbiumin Nanocrystalline Yttrium Orthovanadate

Terbium-doped YVO4has been considered anonluminescent solid since thefirst classic studies on rare-earth-doped phosphors in the 1960s. However, we demonstrate thatdefect engineering of YVO4:Tb3+nanoparticles overcomes themetal-metal charge transfer (MMCT) process which is respon-sible for the quenching of the Tb3+luminescence. Tetragonal(Y1-xTbx)VO4nanoparticles obtained by colloidal precipitationshowed expanded unit cells, high defect densities, and intimatelymixed carbonates and hydroxides, which contribute to a shift of theMMCT states to higher energies. Consequently, we demonstrateunambiguously for thefirst time that Tb3+luminescence can beexcited by VO43--> Tb3+energy transfer and by direct populationof the5D4state in YVO4. We also discuss how thermal treatmentremoves these effects and shifts the quenching MMCT state tolower energies, thus highlighting the major consequences of defect density and microstructure in nanosized phosphors. Therefore,ourfindings ultimately show nanostructured YVO4:Tb3+can be reclassified as a UV-excitable luminescent material

Automated summary

By defect engineering of YVO4:Tb3+ nanoparticles, it is possible to overcome the quenching process and achieve luminescence. The microstructure and defect density of nanoparticles play a crucial role in the performance of phosphors.