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Alternating current poling (ACP) was performed on Gen III relaxor-PT Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (Mn: PIN-PMN-PT) single crystals with the poling direction of [001]. Experimental results proved that ACP could bring property enhancement to both k31 and k33 mode crystals. Compared to those from traditional direct current poling (DCP), ACP with the optimized conditions (20 kV/cm, 0.1 Hz, and 20 cycles) enhanced the dielectric and piezoelectric properties of k31-mode mode crystals by more than 30%, where the enhanced free dielectric constant and piezoelectric coefficient d33 reached 5300 and 1750 pC/N, respectively. Furthermore, replacing DCP with ACP could increase the advantages of Gen III relaxor-PT. The coupling factors k31 and k33 were enhanced to 0.472 and 0.915, the mechanical quality factor Qm was enhanced by 17%, and the depoling temperature was raised by 17 °C to 123 °C. In the following mechanism study, in situ x-ray diffraction (XRD) combined with the temperature-dependent dielectric constant measurement proved the introduction of the monoclinic phases after ACP, while piezoresponse force microscopy (PFM) observation showed "2R"-like "2M" domain morphologies in ACP single crystals. Both these intrinsic and extrinsic factors are believed to be the keys to the mechanisms of property enhancement behind ACP. This study proved that ACP is an effective property enhancement method suitable for Gen III relaxor-PT single crystals and will promote its applications in high-temperature and high-power devices. [ABSTRACT FROM AUTHOR]

Alternating current (electric field) poling (ACP) was applied on [001]-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) single crystal samples with dimensions of 5 × 1.25 × 1.25 mm3 (with electrodes on the 1.25 × 1.25 mm2 surfaces), and the influence of ACP frequency (fACP) was studied. Compared to those from traditional direct (electric field) poling samples, the piezoelectric coefficient (d33) and free dielectric constant (εT33/ε0) of ACP samples could gain up to a 67% increase to 3200 pC/N and 10 500, respectively. The influence of fACP was studied on two main aspects: saturated properties and dynamic saturation process. In general, ACP samples with lower fACP had higher saturated d33, εT33/ε0, and coupling factor k33, as well as lower dielectric loss and faster saturation speed. The ACP dynamics during the saturation process were studied by measuring the polarization-vs-electric field hysteresis loops (P-E loops). The P-E loops illustrated that the coercive field of ACP samples could be further tuned from 1.84 kV/cm to 3.03 kV/cm by changing fACP (0.1–10 Hz). This work demonstrated the enormous potential of ACP optimization in relaxor-PT single crystal-based low-frequency transducer applications. [ABSTRACT FROM AUTHOR]

Diffuse scattering and relaxor behavior in Na0.5Bi0.5TiO3 (NBT) and NBT-5.6 at. %BaTiO3 (NBT-5.6%BT) were investigated. X-ray diffraction revealed two types of diffuse scattering in NBT: (i) broad and (ii) asymmetric L-shaped. After modification with 5.6%BT, the broad diffuse scattering patterns became narrow, and the asymmetric L-shaped ones were replaced by symmetric ones. The symmetric diffuse scattering in NBT-5.6%BT disappeared with increasing dc electric field (E) for E ≥ 9.5 kV/cm where the frequency dispersion in the dielectric constant disappeared. These results demonstrate that the relaxor characteristics are directly correlated with the diffuse scattering and the presence polar nano-regions. [ABSTRACT FROM AUTHOR]

Sliver-mode 0.73Pb(Mg 1/3 Nb 2/3)O 3 -0.27PbTiO 3 single crystals were poled by the alternating current electric field (ACP) along the [001] direction for low-frequency transducer applications. Under ACP with optimized conditions (2.89 kV rms , 0.1 Hz, 10 cycles), the free dielectric constant (ε T 33 / ε 0) was enhanced from 5300 to 7220 and piezoelectric coefficient (d 33) was improved from 1410 to 1920 pC/N, both are about 36% higher than those under traditional direct current poling. The piezoresponse force microscopy observation and phase-field simulation show the similar domain morphologies evolution. During the ACP process, the domain morphology first changes from '4R' to '2R' configuration, and then the length of the 109° domain wall keeps increasing, which leads to a longer range of ordering and a stable lamellar domain structure in the end. The correlation between the domain morphology and the coercive field is also found in both the experiment and simulation. These findings on the effect and mechanism of ACP will help develop advanced low-frequency single crystal transducer arrays. Evolution of domain structures of rhombohedral PMN-PT during ACP process was studied through the domain morphology tracking, which developed from '4R' to '2R' configuration. The results also show a good correlation between coercive field and domain structure, attributing to a new domain engineering model. [Display omitted] [ABSTRACT FROM AUTHOR]