Antioxidation and High-Resolution Ultrasonic Temperature Sensor Based on Cr<sup>3+</sup>:MgAl<sub>2</sub>O<sub>4</sub> Single Crystal Fiber
Tao Wang, Jian Zhang, Lu Yang, Gao Wang, Na Zhang, Siyuan Wang, Yuqing Yin, Zhitai Jia, Xutang Tao
Abstract
High-quality pure MgAl2O4 and Cr3+:MgAl2O4 crystal fibers were grown using laser heating pedestal growth method successfully. The antioxidation ultrasonic temperature sensors (UTSs) were designed using MgAl2O4 single crystal fibers (SCFs) as the acoustic waveguide for the first time. The ultrasonic velocity and the unit sensitivity were investigated, which illustrate that the MgAl2O4 SCF-UTS is more sensitive compared with the YAG SCF-UTS because of the order–disorder phase transition of the spinel. Furthermore, due to the lattice distortion induced by doping ions, the unit sensitivity was further optimized by 18% when using Cr3+:MgAl2O4 crystal fiber as the probe, and the achieved unit sensitivity of 43.94 ns·C1–·m–1 is the record for SCF-UTS. This work represents a feasible approach for high-resolution temperature sensing through the ultrasonic technique and crystal design and optimization.