Luminescent Properties and Optical Temperature Sensing Performance of CaTa₂O₆:Pr³⁺ Phosphors Under Blue-Light...

Pr³⁺-activated phosphors are promising for non-contact optical thermometry under blue-light excitation. In tantalate hosts, Pr³⁺-Ta⁵⁺ intervalence charge transfer (IVCT) states may introduce thermally activated nonradiative pathways involving the ³P₀ and ¹D₂ levels, thus affecting their thermal quenching behavior and thermometric performance. However, the concentration- and temperature-dependent luminescence of CaTa₂O₆:Pr³⁺ remains unexplored. In this study, CaTa₂O₆:Pr³⁺ phosphors were synthesized via the solid-state reaction method, and a phosphor-in-glass (PiG) composite was fabricated by co-sintering the mixture of the phosphor and the precursor glass (PG) powder. The structural characteristics and the luminescence properties of CaTa₂O₆:Pr³⁺ phosphors under 450 nm excitation were investigated. The IVCT band was confirmed in the excitation spectrum. Optimal Pr³⁺ concentrations were 2 mol% for ³P_J and 0.7 mol% for ¹D₂ emissions. With Pr³⁺/Zr⁴⁺ or Pr³⁺/Sn⁴⁺ co-doping, the emission intensity was enhanced by 1.34 and 1.31 times, respectively. The PiG exhibited similar spectral profiles. An FIR mode based on ³P₁→³H₅/³P₀→³F₂ transitions achieved maximum relative sensitivities of 1.09% K^-1 for the phosphor and 1.18% K^-1 for the PiG at 298 K. These findings suggest that CaTa₂O₆:Pr³⁺-based materials are potential candidates for luminescence thermometry.