Temperature and Irradiation Behavior of Piezoelectric Materials for Nuclear Reactor Sensors

Piezoelectric materials are promising candidates for in-situ monitoring of extreme conditions, including nuclear reactor power and very high temperature. Surface acoustic wave (SAW) devices are ultrasonic sensors that utilize this property and provide a signature signal at a designed frequency. In this work, SAW devices were designed and constructed for two piezoelectric materials, AlN and LiNbO₃. Resulting experiments demonstrated that these signals shift due to reactor power changes (0-300 kW) and temperature changes (20-500^oC). The response signal for AlN device shifted from 180.8 MHz at 20^oC to 173.9 MHz at 400^oC (0.018 MHz/^oC). The response for LiNbO₃ device shifted from 124.4 MHz at 20^oC to 117.4 MHz at 500^oC (0.015 MHz/^oC). The magnitude of these frequency shifts is similar to other published works.