Roundtrips of SAW along multiple routes on a single crystal LiNbO3 ball

Propagation of SAW was investigated on a single crystal LiNbO₃ (lithium niobate) ball. There were ten specific routes, on which roundtrips of SAW are observed, and one or more specific routes, on which multiple reflections of bulk waves are observed. The temperature coefficient of ten types of SAW was about 80 ppm/°C at 25°C, and it was different from that of the bulk wave, which was 50 ppm/°C. We then investigated the relationship between the observed roundtrips of SAW and the calculated electromechanical coupling constant. In the direction where the roundtrip of SAW occurs, the electromechanical coupling constant is large, but the roundtrips of SAW occur in not all directions with large electromechanical coupling constant.