LAUSR

Abstract In order to explore nano-thermometer used in biomedical field, Nd3+/Yb3+/Er3+ tri-doped YPO4 phosphors with uniform rice-like nano-architecture were obtained through a facile hydrothermal procedure. The crystalline composition, particle size and morphology of the samples were detected by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Meanwhile, the up-conversion luminescence (UCL) spectra and energy transfer processes were systematically explored. Furthermore, the thermometric behaviors of YPO4: Nd3+/Yb3+/Er3+ and YPO4: Yb3+/Er3+ were discussed by a comparable method based on the temperature-dependent fluorescence intensity ratio (FIR) from thermal coupling levels of Er3+ (2H11/2/4S3/2 → 4I15/2) upon 808 or 980 nm excitation, and the maximum absolute sensitivity in three-doping system reached 0.0029 K-1 when the temperature is 493 K. Results indicate that Nd3+/Yb3+/Er3+ tri-doped YPO4 phosphors have great potential applications for ratio-metric optical thermometer in biological tissue.