Comprehensive luminescence analysis of YTaO4:Er3 +/Yb3+/Tm3+ co-doped phosphor for optical thermometry and color tunable device applications

Abstract

This study comprehensively investigated the structural, morphological and luminescence properties of YTaO₄ (YTO) phosphors tri-doped with rare earth ions. X-ray diffraction (XRD) confirmed the phase purity and crystallinity of the synthesized samples, while field emission scanning electron microscopy (FE-SEM) revealed comprehensive surface morphology and particle size distribution. The upconversion (UC) mechanisms in the Yb³⁺, Er³⁺ and Tm³⁺ doped system showed that varying Tm³ ⁺ content effectively modulates blue, green, and red emissions through energy transfer processes. The phosphors' thermometric behavior was evaluated in the 301–470 K range, with a maximum relative sensitivity of 0.93 % K⁻¹ being achieved by utilizing thermally coupled levels (TCLs) (²H_11/2 and ⁴S_3/2) of Er³⁺ ions in the as-prepared YTO:Er³⁺/Yb³⁺/Tm³⁺ phosphor. The color tunability of the prepared phosphors was explored through changes in dopant concentration, laser power, and temperature variations. These findings demonstrate the potential of YTaO₄: Er³⁺/Yb³⁺/Tm³⁺ phosphors for color-tunable luminescence and non-contact temperature sensing applications.