@article{negi_kim_hua_timofeeva_zhang_zhu_peters_kumah_jiang_liu_2023, title={Ferroelectric Domain Wall Engineering Enables Thermal Modulation in PMN-PT Single Crystals}, volume={4}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.202211286}, DOI={10.1002/adma.202211286}, abstractNote={AbstractActing like thermal resistances, ferroelectric domain walls can be manipulated to realize dynamic modulation of thermal conductivity (k), which is essential for developing novel phononic circuits. Despite the interest, little attention has been paid to achieving room‐temperature thermal modulation in bulk materials due to challenges in obtaining a high thermal conductivity switching ratio (khigh/klow), particularly in commercially viable materials. Here, room‐temperature thermal modulation in 2.5 mm‐thick Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–xPT) single crystals is demonstrated. With the use of advanced poling conditions, assisted by the systematic study on composition and orientation dependence of PMN–xPT, a range of thermal conductivity switching ratios with a maximum of ≈1.27 is observed. Simultaneous measurements of piezoelectric coefficient (d33) to characterize the poling state, domain wall density using polarized light microscopy (PLM), and birefringence change using quantitative PLM reveal that compared to the unpoled state, the domain wall density at intermediate poling states (0< d33<d33,max) is lower due to the enlargement in domain size. At optimized poling conditions (d33,max), the domain sizes show increased inhomogeneity that leads to enhancement in the domain wall density. This work highlights the potential of commercially available PMN–xPT single crystals among other relaxor‐ferroelectrics for achieving temperature control in solid‐state devices.}, journal={ADVANCED MATERIALS}, author={Negi, Ankit and Kim, Hwang Pill and Hua, Zilong and Timofeeva, Anastasia and Zhang, Xuanyi and Zhu, Yong and Peters, Kara and Kumah, Divine and Jiang, Xiaoning and Liu, Jun}, year={2023}, month={Apr} }
 @article{kim_wan_lee_yamashita_jo_jiang_2023, title={Thermal stability studies of alternating current poled Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals grown by solid-state crystal growth}, volume={11}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2022.2161841}, abstractNote={Thermal stabilities of relaxor-PbTiO3 single crystals are of great importance due to their limited operational temperatures in devices. Herein, to elucidate how poling conditions influence thermal stabilities, we investigated direct current (DC) and alternating current (AC) poled Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-29PT) crystals grown by solid-state crystal growth, which guarantees more compositional uniformity. Our experiments show that the dielectric permittivity of the DC and AC poled crystals are 3560 and 4970, respectively, after annealing at 99.6°C, implying AC-poling prevails in enhancing thermal stabilities of relaxor-PbTiO3 single crystals. The mechanism behind the dissimilar thermal stabilities can be attributed to different domain configurations. GRAPHICAL ABSTRACT IMPACT STATEMENT Alternating-current poling is of useful for not only enhancing piezoelectric and dielectric properties but also improving the thermal stabilities of relaxor-PbTiO3 single crystals.}, number={5}, journal={MATERIALS RESEARCH LETTERS}, author={Kim, Hwang-Pill and Wan, Haotian and Lee, Ho-Yong and Yamashita, Yohachi and Jo, Wook and Jiang, Xiaoning}, year={2023}, month={May}, pages={383–390} }
 @article{wan_luo_kim_chung_chang_yamashita_jiang_2022, title={<p>The overpoling effect of alternating current poling on rhombohedral Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals</p>}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0086057}, abstractNote={The overpoling effect of alternating current poling (ACP) was studied on [001]-orientated rhombohedral Pb(Mg1/3Nb2/3)O3-0.26PbTiO3 (PMN-0.26PT) single crystals. Our experimental results showed that the property enhancement from the ACP was remarkable only when the poling cycle number (NL) was kept low. When ACP was continued after the saturation, dielectric and piezoelectric properties gradually dropped down to traditional direct current poled levels or even lower. Such a decrease in material properties caused by the large NL during ACP was defined as the “overpoling effect of ACP” in this study. The following lattice symmetry and domain structure characterization studies were performed through x-ray diffraction (XRD) and piezoelectric force microscopy (PFM) to find the origin of the overpoling effect. The XRD measurements combined with temperature dependence of dielectric properties demonstrated that the field-induced phase transition continued when the samples became overpoled. Further PFM measurements illustrated that the domain density of the overpoled ACP sample was significantly lower than that of the normal one, while the “2R” domain configuration was maintained through the ACP process. In addition, the hysteresis loop characterization indicated large decreases in the coercive fields. The discovered overpoling effect of ACP could help us understand the mechanisms of ACP and optimize the ACP process.}, number={19}, journal={APPLIED PHYSICS LETTERS}, author={Wan, Haotian and Luo, Chengtao and Kim, Hwang-Pill and Chung, Ching-Chang and Chang, Wei-Yi and Yamashita, Yohachi and Jiang, Xiaoning}, year={2022}, month={May} }
 @misc{yamashita_karaki_lee_wan_kim_jiang_2022, title={A Review of Lead Perovskite Piezoelectric Single Crystals and Their Medical Transducers Application}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3160526}, abstractNote={Piezoelectric materials have been developed since early 1900s and many research had been conducted on the composition and process to obtain higher piezoelectric constants (<inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula>). Within composition research, lead perovskite relaxor piezoelectric single crystals (SCs) of Pb(Mg1/3Nb2/3)O3–lead titanate PbTiO3 type have been actively studied since 1990s because of their outstanding <inline-formula> <tex-math notation="LaTeX">${d}_{33} >1500$ </tex-math></inline-formula> pC/N compared with those of the conventional Pb(Zr,Ti)O3 ceramics. A major driving force of these SC research has been promoted by mass production of ultrasound transducers and array probes for medical diagnostic systems since early 2000s. However, higher <inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula> material and process research for these ultrasound devices are almost saturated. In this review article, we present a brief overview of the history, current situation, and future perspective of piezoelectric SCs. The authors believe that the main research in the next century is high <inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula> SCs with a high composition uniformity and low-energy SC growth methods, such as solid-state SC growth, low-loss SC transducer manufacturing technique, and improved poling process. This is a big technical challenge for all the scientists; however, the relatively large market of medical ultrasound has been expanded year by year, and we hope that the community is motivated to solve such technical problems in the near future.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Yamashita, Yohachi and Karaki, Tomoaki and Lee, Ho-Yong and Wan, Haotian and Kim, Hwang-Pill and Jiang, Xiaoning}, year={2022}, month={Nov}, pages={3048–3056} }
 @article{sun_ota_fujii_yamashita_kim_wan_jiang_karaki_2022, title={Enhanced Properties of 3-MHz Sliver-Mode Vibrators for Cardiac Probes With Alternating Current Poling for Pb(Mg1/3Nb2/3)O-3-PbTiO3 Single Crystals}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3199741}, abstractNote={We investigated the effects of alternating current poling (ACP) on the piezoelectric and dielectric properties of 3-MHz sliver mode (L13 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> W0.10–0.25 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> W24 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> T0.48 mm) exhibited ultrahigh dielectric permittivity (<inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula>) and piezoelectric coefficient (<inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula>) 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 <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> values decreased from the SC plate <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> values to 6050, 7080, 8140, and 8540, respectively. The sliver mode electromechanical coupling factors (<inline-formula> <tex-math notation="LaTeX">${k}'_{33}$ </tex-math></inline-formula>) 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 <inline-formula> <tex-math notation="LaTeX">${k}'_{33}$ </tex-math></inline-formula> 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.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Sun, Yiqin and Ota, Yuhei and Fujii, Tadashi and Yamashita, Yohachi and Kim, Hwang-Pill and Wan, Haotian and Jiang, Xiaoning and Karaki, Tomoaki}, year={2022}, month={Nov}, pages={3087–3094} }
 @article{sun_ota_kim_fujii_yamashita_karaki_jiang_wang_2022, title={Enhanced piezoelectric and dielectric properties of AC poled sliver-mode Pb(In1/2Nb1/2)O-3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals for ultrasonic abdomen probes}, volume={61}, ISSN={["1347-4065"]}, DOI={10.35848/1347-4065/ac8142}, abstractNote={Abstract
               The effect of AC poling (ACP) on the piezoelectric and dielectric properties of diced sliver-mode vibrators (L13 × W0.15–0.30 × T0.51 mm3) was investigated for a convex abdomen ultrasound (US) probe that is made of a large Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3−0.3PbTiO3 (PIN-PMN-PT) single crystal (SC) plate (L13 × W60 × T0.51 mm3). The SC was manufactured by the continuous feeding Bridgman (CF-BM) method. The 
                     


                     
                        
                           
                              ε
                           
                           
                              33
                           
                           
                              T
                           
                        
                     
                     
                  /ε
                  0 aging rate (AR) of both DCP and ACP large plate SCs were found to be within 1%/decade suggesting no obvious property degradation. After array dicing, a considerable decrease in electromechanical and dielectric properties was observed. After a post-dicing DCP, the diced DCP-DCP 0.15 mm wide SC slivers showed 
                     


                     
                        
                           
                              ε
                           
                           
                              33
                           
                           
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                  /ε
                  0 and electromechanical coupling factor (k′33) of 4300 and 89.1%, respectively. The diced ACP-DCP 0.15 mm wide SC slivers showed improved 
                     


                     
                        
                           
                              ε
                           
                           
                              33
                           
                           
                              T
                           
                        
                     
                     
                  /ε
                  0 and k′33 of 5980 and 92.2%, respectively, which are considered useful in practical medical array transducer applications.}, number={SN}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Sun, Yiqin and Ota, Yuhei and Kim, Hwang-Pill and Fujii, Tadashi and Yamashita, Yohachi and Karaki, Tomoaki and Jiang, Xiaoning and Wang, Zhuangkai}, year={2022}, month={Nov} }
 @article{kim_wan_lu_yamashita_jiang_2022, title={Scaling effects in the alternating-current poling of thin PIN-PMN-PT single crystals}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0084994}, abstractNote={AC-poling of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals with a thickness of 0.06–0.16 mm was studied in this paper. Compared with DC-poled samples, enhancements in piezoelectric and dielectric properties can be obtained when the thickness is above 0.1 mm. However, inconsistency in poling effects was found in the crystals with thickness below 0.1 mm. To elucidate why such scaling effect arises, surface roughness was measured by an atomic force microscopy to correlate surface morphology and poling effects. It was found that non-uniform surface roughness led to inconsistent and decreased properties. Furthermore, temperature-dependent dielectric permittivity spectra were measured to explore how crystal thickness affects the thermal stability of ferroelectric phases. It is noted that complex changes in crystallographic symmetries emanate by decreasing thickness. Such phenomena can be attributed to more influential effects of surface morphology when thickness is reduced. We hope this work suggests a clue for solving the scaling effects of AC-poling on relaxor-PbTiO3 single crystals.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Hwang-Pill and Wan, Haotian and Lu, Xuanming and Yamashita, Yohachi and Jiang, Xiaoning}, year={2022}, month={Apr} }