Fabrication of REVO4 films via sacrificial conversion from layered rare-earth hydroxide (LRH) films: the investigation of the transition mechanism and their photoluminescence

摘要

Rare-earth orthovanadate REVO4 (RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Y) films were directly synthesized within 2 hours by sacrificial conversion from electrodeposited layered rare-earth hydroxide (RE2(OH)(5)NO3 center dot nH(2)O) films at pH similar to 10, without subsequent heat treatment. Detailed characterization of the products was achieved by combined X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence excitation and photoluminescence. The mechanisms of phase and morphology evolution from Y-2(OH)(5)NO3 center dot nH(2)O to YVO4 were unveiled through systematic investigations into the influences of the concentration of the anion sources (Na3VO4) and the reaction temperature. The effects of lanthanide contraction on the phase structure and particle morphology of the REVO4 films were also clarified. Additionally, the photoluminescence of RE3+ activators (RE = Eu, Dy, and Eu and Dy) was elaborated with YVO4 as a representative host lattice, and the color-tunable emission and energy transfer from Dy3+ to Eu3+ were also investigated. Electrodeposition combined with a hydrothermal anion exchange technique established in this study led to the rapid synthesis of REVO4 films, and it might have wide implications for the generation of other types of inorganic functional films.

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