Relationship between Mechanical Loss and Phases of Physical Constants in Lead-Zirconate-Titanate Ceramics

Mechanical loss in lead-zirconate-titanate (PZT) based piezoelectric ceramics was studied by introducing three complex physical constants: a complex elastic, a dielectric, and a piezoelectric constant. The elastic and dielectric losses had finite values, while the piezoelectric loss was negligibly small. More than 60% of the mechanical loss at resonance under a relatively low vibration-velocity was the elastic-origin component, and the rest was the dielectric-origin component. The dielectric-origin component rose sharply, however, as the vibration-velocity increased and became dominant at high vibration-velocity. The mechanical loss was reduced by doping Fe2O3 into the PZT, which was apparently caused by pinning of the ferroelectric domain wall.