Loss mechanisms in piezoelectrics: how to measure different losses separately

Losses in piezoelectrics are considered in general to have three different mechanisms: dielectric, mechanical, and piezoelectric losses. This paper deals with the phenomenology of losses first, then how to measure these losses separately in experiments. We found that heat generation at off-resonance is caused mainly by dielectric loss tan /spl delta/´ (i.e., P-E hysteresis loss), not by mechanical loss, and that a significant decrease in mechanical Q/sub m/ with an increase of vibration level was observed in resonant piezoelectric ceramic devices, which is due to an increase in the extensive dielectric loss, not in the extensive mechanical loss. We propose the usage of the antiresonance mode rather than the conventional resonance mode, particularly for high power applications because the mechanical quality factor Q/sub B/ at an antiresonance frequency is larger than Q/sub A/ at a resonance frequency.