High Temperature Characteristics of Bi4Ti3O12/Aluminum Oxide Ultrasonic Transducers

Abstract

In this study, lead-free Bi <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> TbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> (BiT)/aluminum oxide(AO) was fabricated. The sample was spray-coated with a BiT/AO sol-gel complex on a titanium substrate (thickness 3mm) to obtain a film thickness of 50µm. Then, the polarization treatment was performed at room temperature, and the top electrode was prepared with a silver paste. The maximum temperature test was performed using the sample. BiT/AO showed high temperature durability up to 670 °C. The result was high temperature durability comparable to other BiT-based ultrasonic transducers. The top electrode was automatically made by sputtering to improve human error and high temperature characteristics during the manufacture of the top electrodes. The material used was copper. As a result of the maximum temperature test, it showed the same high temperature durability as silver paste. However, as the temperature rose, the sensitivity dropped sharply. Therefore, sputtered copper is not the best method for hot top electrode materials. The top electrode needs to be improved with a different material.