Optical temperature sensor based on upconversion luminescence of Er3+doped GdTaO4phosphors

For the development of optical temperature sensor, a series of GdTaO(4)phosphors with various Er3+-doping concentrations (0, 1, 5, 10, 25, 35, 50 mol%) were synthesized by a solid-state reaction method. The monoclinic crystalline structure of the prepared samples was determined by X-ray diffraction (XRD). Under excitations of 980 and 1550 nm lasers, the multi-photon-excited green and red upconversion (UC) luminescence emissions of Er(3+)were studied, and the critical quenching concentration of Er3+-doped GdTaO(4)phosphor was derived to be 25 mol%. By changing the pump power of laser, it was found that the two-photon and three-photon population processes happened for the UC emissions of Er3+-doped GdTaO(4)phosphors excited by 980 and 1550 nm lasers, respectively. Furthermore, based on the change of thermo-responsive green UC luminescence intensity corresponding to the H-2(11/2) -> (4)I(15/2)and(4)S(3/2) -> (4)I(15/2)transitions of Er(3+)with temperature, the optical temperature sensing properties of Er3+-doped GdTaO(4)phosphor were investigated under excitations of 980 and 1550 nm lasers by using the fluorescence intensity ratio (FIR) technique. It was obtained that the maximum absolute sensitivity (S-A) and relative sensitivity (S-R) of Er3+-doped GdTaO(4)phosphors are as high as 0.0041 K(-1)at 475 K and 0.0112 K(-1)at 293 K, respectively. These significant results suggest that the Er3+-doped GdTaO(4)phosphors are a promising candidate for optical temperature sensor.

Automated summary

A series of GdTaO(4)phosphors with different Er3+ doping concentrations were synthesized and studied for their upconversion luminescence properties and temperature sensing capabilities, revealing high potential for optical temperature sensing applications.