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Relaxor-PbTiO3 (PT-based) ferroelectric single crystals are important for many piezoelectric applications because of their outstanding performances. In order to expand their usage and avoid the failure during application, frequency dependence of coercive fields EC for [001]- and [011]-poled rhombohedral Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals was investigated from the frequency of 1 Hz to 300 kHz by using hysteresis loop measurement (frequency: from 1 Hz to 2 kHz) and a critical value method (frequency: from 5 to 300 kHz). The results showed that the coercive field EC, remnant polarization Pr, and saturation polarization Ps strongly depended on the crystal orientation and frequency. Compared with the [001]-poled crystals, the [011]-poled PIN-PMN-PT single crystals possessed higher EC, Pr, and Ps at the same testing frequencies. With increasing frequency from 1 Hz to 300 kHz, the coercive fields EC of the [001]- and [011]-poled PIN-PMN-PT single crystals increased from 4.0 and 4.8 kV/cm to 11.5 and 14.9 kV/cm, respectively. Moreover, the frequency dependence of the coercive fields was found to be consistent with the growth kinetics model, where the coercive fieldsEC were proportional to ƒβ. This work benefits to the design of piezoelectric devices based on PIN-PMN-PT single crystals operated at high frequencies and high driving fields. [ABSTRACT FROM AUTHOR]

Flexoelectricity yields electric polarization through graded strains and exists in various kinds of solid dielectrics but usually with a weak coupling response. In this letter, several Bi-doped Pb(Mg2/3Nb1/3)O3-xPbTiO3 (PMN-xPT) ferroelectric ceramics were prepared and the interplay of their piezoelectricity and flexoelectricity was systematically investigated. The largest flexoelectric response (∼300 μC/m) was 30 times larger than that of pure PMN-PT and was observed in the Bi-doped PMN-32PT, where the after poling piezoelectric coefficients were also the largest (990 pC/N) among all the compositions. This suggests that the apparent flexoelectricity in ferroelectrics is highly related to the bulk piezoelectricity. Therefore, introducing a local structural heterogeneity is considered as a feasible approach to achieve an ultrahigh piezoelectric response while also providing an ultrahigh flexoelectricity. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed. [ABSTRACT FROM AUTHOR]

The property degradation observed in thin Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) crystals is believed to relate to large domains and subsequent clamping induced by the surface boundary. In this work, the properties were investigated as function of domain size, using controlled poling. The degraded piezoelectric and dielectric properties of thin PMN–PT were found to increase significantly with decreasing domain size. Furthermore, the fine domain structure was found to be stable at 3kVcm−1 after 7.0×105 negative-pulse cycles. These properties make PMN–PT crystals suitable for high-frequency (>20MHz) ultrasound transducers. [Copyright &y& Elsevier]