LAUSR

Yb3+/Ho3+ co-doped Y6WO12 nanocrystals with different concentrations of Ho3+ ions have been synthesized through a facile hydrothermal method followed by a subsequent heat treatment. The nanostructures, morphologies, and up-conversion luminescent properties of the as-prepared Y6WO12:Yb3+/Ho3+ nanocrystals were investigated by powder x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectra. XRD results indicate that all the diffraction peaks of the samples match well with the cubic phase of Y6WO12. SEM images demonstrate that the samples consist of spherical-like nanoparticles ranging in size from about 30 nm to 50 nm, which increases slightly with the increase of sintering temperature. Under the excitation of a 980 nm diode laser, the as-prepared nanocrystals show bight red and green luminescence, which is attributed to the transition of 5F5 → 5I8 and 5F4, 5S2 → 5I8 of Ho3+, respectively. With the elevation of the heat treatment temperature from 700°C to 900°C, the up-conversion emission intensity goes up significantly. Additionally, the decay lifetimes data follow a bi-exponential nature. Both the emission intensity (red and green) and their corresponding decay lifetimes increase with increasing Ho3+ concentration, maximizing at 1.0 mol.%, and then decrease, which is mainly attributed to the concentration quenching effect.