ABSTRACT
The loss mechanisms in piezoelectric materials are of three fundamental types: dielectric, mechanical and electromechanical. We will consider first the phenomenology of losses and then examine the methods by which the individual losses are measured. It is generally observed that the generation of heat in a piezoelectric material is due mainly to the intensive dielectric loss, tanδ' (that associated with dielectric hysteresis) when driven off-resonance, while the heating is due primarily to the intensive mechanical loss, (that associated with elastic hysteresis) when the component is driven at resonance. Further, a significant decrease in the mechanical quality factor, Qm, accompanied by an increase in vibration is observed for piezoelectric ceramic devices driven at resonance. This effect is due entirely to an increase in the extensive dielectric loss. When subjected to a pulse drive, both off-resonance and resonance effects are manifested simultaneously, and the combined action of the dielectric and mechanical loss mechanisms is observed.
