Achieved High-Sensitivity Single-Band Ratiometric Optical Thermometry by Manipulating the Intervalence Charge-Transfer Band Position.

Abstract

Currently, optical thermometry has received widespread attention because of its noncontact and wide temperature range, but most of them are based on the application of dual-band optical ratiometric thermometry, so the development of a single-band ratiometric (SBR) optical thermometry, which is easier to analyze and use, is particularly important. In this work, the position of the intervalence charge-transfer (IVCT) band for Na₂Gd_2-xLa_xTi₃O₁₀:Pr³⁺ (x = 0, 0.5, 1.0, 1.5, 2.0) was modulated using Gd/La substitution, enhancing the thermal response difference of Pr^{3+ 1}D₂ → ³H₄ under charge-transfer band (CTB) and IVCT band excitation, thereby achieving high-sensitivity SBR optical thermometry, and the maximum relative sensitivity (S_r-max) reached 2.95% (at 298 K). In addition, this series of phosphors has high-color-purity red emission, indicating that it has potential for multifield applications.