Design and Directional Growth of (Mg1−xZnx)(Al1−yCry)2O4 Single‐Crystal Fibers for High‐Sensitivity and High‐Temperature Sensing Based on Lattice Doping Engineering and Acoustic Anisotropy

Abstract

AbstractHigh‐performance temperature sensors for the harsh environment are vital components for meeting the increasing demands for the development of existing and emerging technologies. In this study, specifically oriented (Mg1−xZnx)(Al1−yCry)2O4 single‐crystal fibers (SCF) are grown by the laser‐heated pedestal growth technique and used as acoustic waveguides for ultrasonic temperature sensors (UTS) for the first time. The anisotropic sensor performance of the MgAl2O4 SCF‐UTS are investigated under a longitudinal wave and transverse wave conditions, and the [110]‐oriented MgAl2O4 SCF‐UTS is found to have the highest sensitivity and resolution among all the MgAl2O4 SCF‐UTS. On this basis, a unit sensitivity of 40.38–67.50 ns °C−1 m−1 and a resolution of 1.24–0.74 °C are achieved for the [110]‐oriented (Mg0.9Zn0.1)(Al0.995Cr0.005)2O4 SCF‐UTS in the range of 20–1200 °C, both of which represent the best sensor performance achieved by a SCF‐UTS to date. The positive temperature‐dependent sensor performance, accompanied by a high working temperature (≈2000 °C) and outstanding anti‐oxidation, indicates that the [110]‐oriented (Mg0.9Zn0.1)(Al0.995Cr0.005)2O4 SCF‐UTS is a promising candidate for ultra‐high temperature sensors. This study demonstrates a feasible strategy for the rational design of high‐performance temperature sensors through a combination of crystal design, acoustic anisotropy, and lattice doping engineering.