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·C^1–·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.

中文翻译：

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Cr ³⁺：MgAl ₂ O ₄单晶纤维的抗氧化高分辨率超声波温度传感器

利用激光加热基座生长法成功地生长了高质量的纯MgAl ₂ O ₄和Cr ^{3 +}：MgAl ₂ O ₄晶体纤维。首次使用MgAl ₂ O ₄单晶纤维（SCFs）作为声波导来设计抗氧化超声温度传感器（UTSs）。研究了超声速度和单位灵敏度，表明MgAl ₂ O ₄与YAG SCF-UTS相比，SCF-UTS更为敏感，因为尖晶石的有序-无序相变。此外，由于掺杂离子引起的晶格畸变，当使用Cr ^{3 +}：MgAl ₂ O ₄晶体光纤作为探针时，单位灵敏度进一步优化了18％，达到了43.94 ns·C ^1– ·的单位灵敏度。m ^–1是SCF-UTS的记录。这项工作代表了通过超声技术以及晶体设计和优化进行高分辨率温度感测的可行方法。