Er3+ doping YbTaO4 phosphors: Upconversion luminescence and temperature sensing characteristics

Trivalent erbium (Er 3+ ) doped trivalent ytterbium (Yb 3+ ) stoichiometric upconversion (UC) phosphors YbTaO 4 (YbTaO 4 :Er 3+ ) synthesized using the high temperature solid-state reaction method. The phase structure was analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM) and XRD Rietveld refinement methods. The vibration of the bonds was revealed through Fourier transform infrared (FT-IR) spectroscopy. The multi-photon UC green and red luminescence were investigated upon excitation with a 980 nm semiconductor laser , and the critical quenching concentration of Er 3+ in the YbTaO 4 stoichiometric host was derived as high as 15 at.%. The power-dependent UC emission spectra confirmed a two-photon population process for the UC green and red emissions. Furthermore, the temperature-dependent UC emission spectra were measured in the range of 300–570 K, and the optical temperature sensing performance of YbTaO 4 :Er 3+ was demonstrated using the fluorescence intensity ratio (FIR) technique. The maximum absolute sensing sensitivity (S A ) and relative sensing sensitivity (S R ) of YbTaO 4 :Er 3+ were determined as 0.0038 K -1 (@450 K) and 0.0102 K -1 (@300 K), respectively. These results suggest that Er 3+ doped YbTaO 4 stoichiometric phosphors hold great promise as upconversion materials for optical temperature sensing applications.