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We investigated the effects of alternating current poling (ACP) on the piezoelectric and dielectric properties of 3-MHz sliver mode (L13 mm $\times $ W0.10–0.25 mm $\times $ T0.48 mm) vibrators fashioned from Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-0.30PT) single crystal (SC) plate manufactured using the continuous-feeding Bridgman (CF-BM) method for cardiac probes. The ACP SC plate (L13 mm $\times $ W24 mm $\times $ T0.48 mm) exhibited ultrahigh dielectric permittivity ($\varepsilon ^{T}_{33}/\varepsilon _{0}$) and piezoelectric coefficient (${d}_{33}$) of 9690 and 2920 pC/N, respectively. After array dicing, the SC slivers with widths of 0.10, 0.15, 0.20, and 0.25 mm were obtained, and their average $\varepsilon ^{T}_{33}/\varepsilon _{0}$ values decreased from the SC plate $\varepsilon ^{T}_{33}/\varepsilon _{0}$ by 45% (5330), 29% (6880), 19% (7840), and 15% (8240), respectively, possibly because of heat and mechanical damage during the dicing. A combination of the ACP and a postdicing direct current poling (ACP-DCP) recovered their $\varepsilon ^{T}_{33}/\varepsilon _{0}$ values to 6050, 7080, 8140, and 8540, respectively. The sliver mode electromechanical coupling factors (${k}'_{33}$) were confirmed to exceed 93% after the ACP-DCP process, which were more than 4% higher than those of DCP-DCP SC slivers. The measured impedance spectra indicated that the SC slivers with 0.10–0.20 mm in width showed no spurious mode vibration near the fundamental ${k}'_{33}$ mode. We conclude that the ACP-DCP SC slivers maintained more enhanced piezoelectric and dielectric properties than the DCP-DCP samples. These results will have important implications for the commercial application of ACP technology to medical imaging ultrasound probes. [ABSTRACT FROM AUTHOR]

With the great success on verifying its effectiveness on relaxor-PbTiO3 (PT) single crystals (SCs), alternating current poling (ACP) has been taking a center as a new domain engineering method in the last few years. Compared with the conventional direct current poling (DCP), ACP enables enhanced piezoelectric and dielectric properties. In this article, research progress in ACP and perspectives are introduced. Initially, optimized conditions of ACP for relaxor-PT SCs and unsolved issues on polycrystalline ceramics and spurious modes are reviewed. Second, the ferroelectric domain size dependence of piezoelectricity associated with ACP is discussed. We hypothesize that a tradeoff between domain and domain wall contributions exists for high piezoelectricity, suggesting an optimum 109° domain wall size, which is presumably dependent on compositions, crystallographic symmetries, and domain configurations. Finally, crystals synthesized by a solid-state crystal growth (SSCG) method are briefly introduced due to their unprecedented piezoelectricity obtained by ACP (${d}_{33} \sim 5500$ pC/N). We hope that this work helps to grasp the current status of ACP and to guide future tasks to be studied. [ABSTRACT FROM AUTHOR]

Sodium niobate NaNbO3 hydrate ( NN-hydrate) particles with a plate-like morphology were prepared at 140°C for 2 h in 12 mol/L of NaOH by the hydrothermal method. Bar-like Na8Nb6O19·13H2O particles were synthesized at as low as 100°C for 2 h. This work demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures, including the bar-like, plate-like, fibers and cube particles through a direct reaction between NaOH solution and Nb2 O5. It was found that Nb6 O198− formed was an important premise for formation of the NN-hydrate, and lower [ OH-] was not favorable in preparing the NN-hydrate as there was an optimum [ OH−]. Through researching effects of the reaction temperature, time, concentration of NaOH, and content of Nb2 O5 on the NN-hydrate structure and evolution, the formation mechanism from solid reactants to the intermediate were investigated. After calcining at 800°C, the synthesized NN-hydrate particles made a phase almost transform to the perovskite NaNbO3, and the morphology of these calcined particles was still plate-like. [ABSTRACT FROM AUTHOR]

We investigated the effects of alternating current poling (ACP) on the piezoelectric and dielectric properties of 3-MHz sliver mode (L13 mm × W0.10-0.25 mm × T0.48 mm) vibrators fashioned from Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-0.30PT) single crystal (SC) plate manufactured using the continuous-feeding Bridgman (CF-BM) method for cardiac probes. The ACP SC plate (L13 mm × W24 mm × T0.48 mm) exhibited ultrahigh dielectric permittivity ( ε T 33 /ε 0 ) and piezoelectric coefficient ( d 33 ) of 9690 and 2920 pC/N, respectively. After array dicing, the SC slivers with widths of 0.10, 0.15, 0.20, and 0.25 mm were obtained, and their average ε T 33 /ε 0 values decreased from the SC plate ε T 33 /ε 0 by 45% (5330), 29% (6880), 19% (7840), and 15% (8240), respectively, possibly because of heat and mechanical damage during the dicing. A combination of the ACP and a postdicing direct current poling (ACP-DCP) recovered their ε T 33 /ε 0 values to 6050, 7080, 8140, and 8540, respectively. The sliver mode electromechanical coupling factors ( k' 33 ) were confirmed to exceed 93% after the ACP-DCP process, which were more than 4% higher than those of DCP-DCP SC slivers. The measured impedance spectra indicated that the SC slivers with 0.10-0.20 mm in width showed no spurious mode vibration near the fundamental k' 33 mode. We conclude that the ACP-DCP SC slivers maintained more enhanced piezoelectric and dielectric properties than the DCP-DCP samples. These results will have important implications for the commercial application of ACP technology to medical imaging ultrasound probes.