Improved upconversion luminescence and temperature sensing in Mo6+-doped LuNbO4: Er3+ phosphor under 1550 nm excitation

LuNbO4: Mo6+, Er3+ phosphors were prepared via a solid-state reaction and characterized by x-ray diffraction (XRD) and upconversion luminescence (UCL) as well as temperature-dependent UC spectra. Under 1550 nm excitation, the characteristic UCL of the Er3+ ion, which originates from a three-photon process, is observed. An obvious UC enhancement can be found when the Mo6+ ions are doped, which may be attributed to the lower symmetry around Er3+. The optical thermometry behavior was studied as well. It is found that the maximum sensitivity is improved from 0.0053 K-1 to 0.0069 K-1 and the temperature revolution increases from 1.0 K to 0.7 K. Therefore, this work will provide a path for improving UCL and sensing sensitivity in Er3+-doped systems at an excitation of 1550 nm.