Study on optical temperature sensing properties of YVO4:Er3+, Yb3+ nanocrystals

Abstract

The YVO4: Er3+, Yb3+ phosphors with various particle sizes were prepared by a precipitation method and the crystal structure and microscopic image were characterized by means of X-ray Diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The up-conversion luminescent spectra of Er3+, Yb3+ co-doped YVO4 nanocrystals with different particle sizes have been measured. It can be found that the red-green upconversion emission intensity ratio increases with the decrease of the particle size. Furthermore, the temperature sensing properties of YVO4: Er3+, Yb3+ phosphors with different particle sizes were studied based on the change of emission intensities from two thermally coupled 2H11/2 and 4S3/2 levels of Er3+. It shows that in a relatively wide range of sensing temperature (293–603K), the temperature sensing sensitivity of nanosized materials is somewhat higher than that of bulk material. The sensing sensitivity of the sample increases with decreasing particle size, and a relative high sensitivity of 1.112×10−2K−1 was obtained for the sample with a particle size of 20nm, which is about 17.3% higher than the bulk sample. Finally, physical mechanism for the size-dependence of temperature sensing sensitivity was explained and predicted.