“…There are primarily two types of dopants for PZT, i.e. the donor type (soft type), and the acceptor type (hard type) (Jaffe et al, 1971). The former is mainly caused by substitution of higher valence ions for the A site Pb or B site Zr and Ti, and correspondingly higher piezoelectric coefficient (d 33 ), planar electromechanical coupling factor (K p ), relative permittivity (ε r ), loss tangent (tgδ), P r values and a lower mechanical quality factor (Q m ) value are obtained.…”