Synthesis and Characterization of Er3+-Doped SrNb2O6 Phosphor for FIR Based Thermometer

A new optical thermometer material—Er3+-doped SrNb2O6—based on the fluorescence intensity ratio was synthesized and investigated by both theoretical calculation and experimental measurement, combining X-ray diffractometry (XRD), XRD Rietveld refinement, scanning electron microscopy, X-ray photon emission spectroscopy, photoluminescence (PL) and PL excitation of qualitative and quantitative analysis, to develop a novel green-emitting phosphor with excellent thermometry sensitivity. The Er3+ ions occupied 4e sites of SrNb2O6, and the stable activator occupation induces luminescence properties of emissions at 525, 531, and 550 nm. The SrNb2O6: Er3+ phosphor possesses an outstanding thermal sensitivity in the measurement region of 298–523 K, where Sa and Sr can achieve 6.15 × 10−3 K−1 and 1093.2711/T2, respectively, at 323 K. The optical thermal properties originated from the thermal excitation and formation of quashing thermal equilibrium between 2H11/2 and 4S3/2 levels, leading to photons on 4S3/2 → 4I15/2 transfer process thermally populate onto 2H11/2 → 4I15/2 transfer process. This work will lay a foundation for further exploration of activator suitability in columbite phosphors, making it practicable to foreseeably improve thermal sensitivity and PL for emergent applications in optical thermometer.