Preparation and Research on the Optical Temperature Sensing Properties of Ho³⁺ doped NaY(MoO₄)₂ Phosphors

Abstract

In this work, NaY(MoO4)2: 5 % Ho3+ were synthesized successfully with sodium citrate as chelating agent by hydrothermal method. As X‐ray diffraction graphs showed, the samples were body‐centered quadrilateral structure. The Field‐emission Scanning Electron Microscope pictures demonstrated the morphology of the experimental samples changed with different amounts of sodium citrate. The temperature‐dependent emission spectra (293‐563 K) revealed different thermal quenching trends of the emission peaks from different energy levels (5F4/5S2→5I7, 5F4/5S2→5I8 and 5F5→5I8). The two groups of fluorescence intensity ratios (FIR) could be applied to temperature measurement (5F4/5S2→5I8 to 5F5→5I8 and 5F4/5S2→5I7 to 5F5→5I8). As sodium citrate content increased, the maximum values of relative sensitivity of the samples increased, among which the greatest one was 0.316 % K−1 (Cit3−/Re3+=2). In addition, the FIR had good repeatability in heating, cooling and heating again process that indicated the temperature sensing properties of the sample were steady. Since it was possible to characterize temperature with two sets of FIR, the samples could play a self‐calibrating character. Summing up the above, the NaY(MoO4)2 : 5 % Ho3+ phosphors were promising optical temperature sensing materials.