Effects of Zr/Ti ratio on structural, dielectric and piezoelectric properties of Mn- and (Mn, F)-doped lead zirconate titanate ceramics

摘要

The influence of the Zr/Ti ratio on the piezoelectric properties of (Mn and 1 at. percent F)-doped PZT and Mn-doped PZT ceramics is investigated. Lead zirconate titanate ceramics (PZT) are prepared from chemical route based on co-precipitation of oxalates and hydroxides. Structural analysis (XRD) and measurement of electrical properties were carried out. Scanning electron microscopy is used to determine the grain size of the materials. The valency states of Mn in fluorinated PZT ceramics are studied by Electron Spin Resonance (ESR). From the experimental results, the F-0 substitution increases the piezoelectric activity at the morphotropic phase boundary (MPB) and the Q_m in the rhombohedral region. In the (Mn, F)-co-doping case, the high-piezoelectric activity found at the MPB is due to an electron transfer mechanism that involved the three valency states of manganese whereas the improvement of Q_m can be explained by the valence state of manganese and the dipole defect concept.