Analysis of excitation of bulk acoustic waves by interdigital transducer at an interface of piezoelectric crystal and liquid

The interdigital transducer (IDT) deposited at an interface of piezoelectric crystal and liquid can generate bulk acoustic waves (BAWs) into the interior of solid and liquid. And this phenomenon may be applied in some practical issues. In this article, the relationship between the excitation efficiency of BAWs by IDT and the orientation of piezoelectric crystal has been analyzed by defining an effective permittivity at the interface. The numerical results show the orientation of piezoelectric crystal with the most efficient excitation of BAWs by IDT. Moreover, the case in which IDT generates BAWs only into the interior of liquid has also been illustrated.