Defect Dipole Thermal-stability to the Electro-mechanical Properties of Fe Doped PZT Ceramics

The accepted doping ion in Ti 4+ -site of PbZr y Ti 1-y O 3 (PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor (Q m ), since the acceptor coupled by oxygen vacancy becomes defect dipole, which prevents the domain rotation.In this field, a serious problem is that generally, Q m decreases as the temperature (T) increases, since the oxygen vacancies are decoupled from the defect dipoles.In this work, Q m of Pb 0.95 Sr 0.05 (Zr 0.53 Ti 0.47 )O 3 (PSZT) ceramics doped by 0.40% Fe 2 O 3 (in mole) abnormally increases as T increases, of which the Q m and piezoelectric coefficient (d 33 ) at room temperature and Curie temperature (T C ) are 507, 292 pC/N, and 345 , respectively.The maximum Q m of 824 was achieved in the range of 120-160 , which is 62.52% higher than that at room temperature, while the dynamic piezoelectric constant (d 31 ) was just slightly decreased by 3.85%.X-ray diffraction (XRD) and piezoresponse force microscopy results show that the interplanar spacing and the fine domains form as temperature increases, and the thermally stimulated depolarization current shows that the defect dipoles are stable even the temperature up to 240 .It can be deduced that the aggregation of oxygen vacancies near the fine domains and defect dipole can be stable up to 240 , which pins domain rotation, resulting in the enhanced Q m with the increasing temperature.These results give a potential path to design high Q m at high temperature.