Er3+, Yb3+ co-doped Sr3(PO4)2 phosphors: A ratiometric luminescence thermometer based on Stark levels with tunable sensitivity

Novel precise thermometers are increasingly important due to the development of electronic and optoelectronic devices. Up-converting Sr-3(PO4)(2):Er3+,Yb3+ phosphor, exhibiting anti-Stokes luminescence has been developed as an optical temperature sensor. The basic physicochemical properties of the synthesized material, i.e. crystal structure, morphology, diffuse reflectance spectrum, up-conversion (UC) emission and the corresponding chromaticity diagram were systematically studied. The UC luminescence properties of the micron-sized particles synthesized are strongly temperature-dependent, from 303 to 623 K. By using a single material, the selection of different Stark sublevels results in various temperature sensitivities. Using band intensity ratio of Er3+ Stark components H-2(11)/2(1)/S-4(3/2(1)), the relative sensitivity of 0.88% K-1 at 303 K was obtained.