Effect of Ga/Al Ratio on Photoluminescence and Optical Temperature Sensing of GAGG:Pr Ceramics
Guangzhi Dong, Rulang Bai, Huanhuan Su, Chaoke Lv, Bilin Zhang, Tao Wang, Wanqi JieABSTRACT
Accurate temperature monitoring is crucial for experiments and industry. Among various approaches, fluorescence‐based temperature measurement using the fluorescence intensity ratio (FIR) technique has attracted considerable interest owing to its contactless operation and immunity to electromagnetic disturbances. Rare‐earth‐doped oxide ceramics are especially promising in optical thermometry applications under extreme conditions. In the present work, a series of Gd 3 Al 5‐ x Ga x O 12 :Pr (GAGG:Pr) ceramics with different Ga/Al ratios (1:4, 2:3, 1:1, 3:2, and 4:1) was synthesized. Increasing the Ga/Al ratio induced lattice distortion and caused the XRD diffraction peaks to shift toward smaller angles. The substitution of Al 3+ by Ga 3+ reduces the characteristic phonon energy and alters the relative EPR signal intensity associated with oxygen‐vacancy‐related F + centers. A systematic blue shift of the photoluminescence emission peaks and composition‐dependent variations in the FIR thermometric response were observed. Increasing temperature induces the gradual thermal quenching of Pr 3+ emission and temperature‐dependent changes in the lattice vibrations. The FIR method confirmed that the temperature sensitivity parameters could be effectively modulated by compositional engineering. For ceramics with a Ga/Al molar ratio of 1:4, the maximum absolute sensitivity within the studied temperature range is S a = 5.68 × 10 −3 K −1 . The pronounced dependence of optical transmittance, PL intensity, resistance to thermal quenching, and FIR sensitivity on composition reveals the trade‐offs in performance among the studied ceramic materials and provides a basis for selecting the Ga/Al molar ratio based on functionality.