Strategies for designing low thermal quenching upconverting temperature sensors

Abstract

The Er³⁺/Yb³⁺:NaGd(WO₄)₂ phosphors and the phosphor-in-glass (PIG) have been synthesized employing a typical approach to investigate their structural, morphological and optical properties. Several PIG samples containing different amounts of NaGd(WO₄)₂ phosphor have been manufactured by sintering the phosphor and glass [TeO₂–WO₃–ZnO–TiO₂] frit together at 550 °C, and its impact on the luminescence characteristics has been extensively studied. It has been noticed that the upconversion (UC) emission spectra of PIG under 980 nm excitation display similar characteristic emission peaks to the phosphors. The maximum absolute sensitivity of the phosphor and PIG is 17.3 × 10⁻³ K⁻¹ @ 473 K and the maximum value of relative sensitivity is 10.0 × 10⁻³ K⁻¹ @ 296 K and 10.7 × 10⁻³ K⁻¹ @ 298 K, respectively. However, thermal resolution at room temperature has been improved in the case of PIG as compared to the NaGd(WO₄)₂ phosphor. As compared to the Er³⁺/Yb³⁺ codoped phosphor and glass, the less thermal quenching of luminescence has been observed in PIG.