Dual optical thermometry in the near-infrared: temperature-driven luminescence in Yb³⁺/Er³⁺‐doped NaYF₄ phosphor

A dual-modal luminescence thermometer is developed based on its attention in scientific research and daily life using erbium and ytterbium co-doped sodium yttrium tetrafluoride phosphors which were synthesized by the microwave-assisted combustion technique. The structural information of the synthesized phosphors were learnt using the powder X-ray diffraction technique. The micro-particulate nature and the homogeneous distribution of particles were confirmed through SEM and EDX studies. The optical bandgap was found to be 4.92 eV from the UV–Vis–NIR absorption spectroscopy. The optical properties were studied by recording the photoluminescence spectra for NaYF₄:3 mol% Yb³⁺, y mol% Er³⁺ samples, and their colorimetric and photometric properties were additionally investigated. The prepared phosphors exhibit the relative sensitivities of 1.08 %K⁻¹, 1.26 %K⁻¹, 0.11 %K⁻¹ as obtained through the FIR (TCL), FIR (NTCL), and chromaticity coordinates, respectively. The photoluminescent performances certify that phosphor has a wide range of possible application in display technique, temperature sensing in addition to IR detection.