Dual‐FIR Channel Thermometer Using Ca ₂ YZr ₂ Al ₃ O ₁₂

ABSTRACT

Developing fluorescence intensity ratio (FIR) optical thermometers with low cost, high sensitivity, and wide measurement range is a key bottleneck in this field, which poses severe challenges to conventional thermosensitive materials. In this work, we synthesized a series of Ca ₂ YZr ₂ Al ₃ O ₁₂ :Bi ³⁺ ,Tb ³⁺ phosphors with both dual‐band emission and anti‐thermal quenching (ATQ) behavior and achieved dual‐FIR channel optical thermometry. Specifically, the dual‐band emission of Bi ³⁺ ions originates from the ³ P ₁ → ¹ S ₀ transition (A‐band) and the Bi ³⁺ –Zr ⁴⁺ charge‐transfer transition (D‐band), while the ATQ behavior of Tb ³⁺ ions is attributed to the synergistic effect of electron–phonon coupling and crystal field. Notably, owing to severe TQ behavior of Bi ³⁺ emission at low‐temperature region, the FIR ₃₀₉ detection channel exhibits highly sensitive temperature sensing from 293 to 433 K ( S _r ≥ 1% K ⁻¹ ). In contrast, the FIR ₂₇₅ channel with Tb ³⁺ ATQ behavior is more suitable for high‐temperature region detection, exhibiting a maximum S _r value of 2.14% K ⁻¹ (at 473 K) and a highly sensitive detection range of 413–573 K. Obviously, the combined temperature detection range (293–573 K) of the dual‐FIR channel is two times that of single FIR ₃₀₉ channel. Moreover, the outstanding temperature measurement performance of the dual‐FIR channel optical thermometer is vividly demonstrated through the optical fiber temperature detection platform. These promising findings offer a new perspective for developing optical thermometers with exceptional performance.