Dielectric Relaxor and Conductivity Mechanism in Fe-Substituted PMN-32PT Ferroelectric Crystal

Abstract

Fe-substituted PMN-32PT relaxor ferroelectric crystals were grown by a high-temperature flux method. The effects of charged defects on the dielectric relaxor and conductivity mechanism were discussed in detail. The Fe-substituted PMN-32PT crystal showed a high coercive field (Ec = 765 V/mm), due to domain wall-pinning, induced by charged defect dipoles. Three dielectric anomaly peaks were observed, and the two dielectric relaxation peaks at low temperature were associated with the diffusion phase transition, while the high temperature one resulted from the short-range hopping of oxygen vacancies. At temperature T ≤ 150 °C, the dominating conduction carriers were electrons coming from the first ionization of oxygen vacancies. For the temperature range from 200 to 500 °C, the conductivity was composed of the bulk and interface between sample and electrode, and the oxygen vacancies were suggested to be the conduction mechanism. Above 550 °C, the trapped electrons from the Ti3+ center were excited and played a major role in electrical conduction. Our results are helpful for better understanding the relationship between dielectric relaxation and the conduction mechanism.

Electrophysical Properties of PMN-PT-Ferrite Ceramic Composites

“…These broad peaks shift towards higher temperatures with increasing frequency of the measurement field. This phenomenon may be associated with the imposition of a number of factors, for instance, as a result of relaxation processes as well as an increase in electrical conductivity in composite samples at high temperatures [36,37,38,39,40].…”

Synthesis and Characterization of Ferroelectrics

“…It is found that such segregation differently influences the electrical properties of the investigated system. While the electrical properties along the axial direction strongly depend on the PbTiO 3 content, the electrical properties along the radial direction are mainly determined by the ratio of Nb and Mg. Another technological route is presented by Li et al [5]. The authors investigated dielectric and conductivity mechanisms of Fe-substituted PMN-32PT crystals.…”