A Lithium Niobate High-Temperature Sensor for Energy System Applications

Temperature monitoring for energy generation systems plays an important role for the control of overall safety and efficiency. To run the energy system at optimum operating conditions, it is important to measure the real-time temperature. Furthermore, harsh environment temperature sensing is desired, since most sensors in energy systems are exposed to high temperature, high pressure, and corrosive environments. Lithium niobate (LiNbO ₃ ) has high Curie temperature (1210 °C), thus making it promising to be used as a sensor material for high-temperature applications. In this paper, a study has been conducted to actively measure the temperature up to 450 °C using a pyroelectric ceramic LiNbO ₃ as a sensor material. A 1 cm × 1 cm sample of LiNbO ₃ ceramic with 0.2 cm thickness was prepared as a sensor. The LiNbO ₃ sensor and a K-type thermocouple were placed inside a tube furnace to sense the temperature. Different temperature setting conditions were applied to the sensor, including slow heating rate, high heating rate, and steady-state conditions for prolonged time period to validate readability and repeatability of the sensor. Temperatures were calculated using current generated from the sensor upon heating or cooling. The calculated temperature from the sensor was compared with the temperature measured by the K-type thermocouple. A range of deviation from 2% to 11% was found between the temperature measured by LiNbO ₃ and thermocouple.