1-3 connectivity lithium niobate composites for high temperature operation

Area of Science:

• Materials Science
• Acoustics
• Non-Destructive Testing

Background:

• Lithium niobate (LiNbO3) possesses a high Curie temperature, making it suitable for high-temperature applications.
• Its low electro-mechanical coupling coefficients have historically limited its use in ultrasonic transducers.
• Advances in signal processing mitigate the impact of low electro-mechanical coupling.

Purpose of the Study:

• Investigate the potential of LiNbO3 composites for high-temperature ultrasonic transducers.
• Evaluate suitability for non-destructive testing (NDT) in elevated temperature environments.
• Develop and characterize novel LiNbO3 composite materials.

Main Methods:

• Fabrication of 1-3 connectivity LiNbO3 composites using the dice and fill method.
• Incorporation of LiNbO3 into room temperature vulcanising (RTV) sealant and cement matrices.
• Characterization via electrical impedance measurements at ambient and elevated temperatures.

Main Results:

• Successfully fabricated LiNbO3 composites with RTV (up to 350°C) and cement (up to 1600°C) matrices.
• Achieved good signal-to-noise ratio in transmit-receive tests on steel specimens at room temperature.
• Demonstrated high-temperature operation up to 180°C (RTV) and 360°C (cement), withstanding temperature cycling without degradation.

Conclusions:

• LiNbO3 composites are viable for high-temperature ultrasonic transducer applications.
• These materials offer a potential solution for previously unsolved NDT problems at elevated temperatures.
• The developed composites exhibit robust performance under thermal stress and cycling.