A study on temperature sensing performance based on the luminescence of Eu3+ and Er3+ co-doped YNbO4

Abstract

Eu³⁺ and Er³⁺ co-doped YNbO₄ powder phosphors were synthesized by a traditional high-temperature solid-state reaction method. A laser of 487.6 nm wavelength was selected to be the excitation source which can pump Eu³⁺ ions from its thermally populated low-lying ⁷F₂ ground state to the excited state ⁵D₂ and lift the Er³⁺ ions from their ⁴I_15/2 to ⁴F_7/2 states. Fluorescence intensity ratio (FIR) between the ⁵D₀ → ⁷F_J emissions of Eu³⁺ and ⁴S_3/2 → ⁴I_15/2 emissions of Er³⁺ ions is remarkably dependent on temperature because of the dramatic increase of Eu³⁺ luminescence against a slight quenching of Er³⁺ luminescence with the rise of temperature. This temperature sensitive FIR can be favorably employed for temperature sensing, owing to this novel scheme of ⁵D₂ excitation, instead of ⁵D₀, from ⁷F₂ and utilizing Er³⁺ luminescence as a reference for FIR measurements. This sample is also prominent for its excellent signal-to-noise ratio and is a promising candidate for an optical temperature sensor.