Controlling Nanoscale Compositional Inhomogeneities to Enhance Tb3+ Luminescence in YVO4 Nanocrystals.

Controlling chemical homogeneity during aqueous coprecipitation of oxide nanoparticles remains challenging due to unintended byproducts that impact the microstructure and functionality of the final materials. Hence, precise tuning of structural, optical, and catalytical properties requires not only accurate knowledge of how such impurities evolve under annealing, but also effective strategies for defect engineering. Here, we demonstrate how hydroxylation and carbonation affect the internal structure and optical properties of YVO4 nanoparticles synthesized using different vanadate precursors. The use of highly basic Na3VO4 promotes unintentional carbonation, leading to Y/V nonstoichiometry and formation of the yttrium-rich Y8V2O17 secondary phase upon annealing. Combined in situ and ex situ characterizations further reveal that CO32- and OH- species embedded in the particle structure induce thermally driven nanovoids and reshape the local defect structure of the solids. More importantly, we expand defect engineering in YVO4:Tb3+ nanoparticles by intentional hydroxylation and carbonation to enhance luminescence intensities. Adjusting these compositional defects enables us to modulate the energy of metal-metal charge transfer (MMCT) deactivation pathways, resulting in up to 13-fold higher emission intensity compared to chemically pure YVO4:Tb3+. These findings establish defect incorporation as an effective route for tailoring the optical response of rare-earth vanadate nanoparticles, opening new opportunities for advanced photonic and luminescent sensing applications.