The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically prac...The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.展开更多
In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a ...In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.展开更多
Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses a...Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.展开更多
High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adop...High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.展开更多
文摘The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.
基金Funded by the National Natural Science Foundation of China (No.50708065)the National High-tech R&D Program(863 Program )(No.2007-AA-11-Z-113)the Key Projects in the Science and Technology Pillar Program of Tianjin(No.11ZCKFSF00300)
文摘In order to monitor the basic mechanical properties and interior damage of concrete structures,the piezoelectric actuator/sensor based wave propagation method was investigated experimentally in the laboratory using a specifically designed test setup.The energy attenuation of stress waves was measured by the relative index between the output voltage of sensors and the excitation voltage at the actuator.Based on the experimental results of concrete cube and cylinder specimens,the effect of excitation frequencies,excitation amplitude,wave propagation paths and the curing age on the output signals of sensors are evaluated.The results show that the relative voltage attenuation coefficient RVAC is an effective indicator for measuring the attenuation of stress waves through the interior of concrete.
基金supported by the Natural Science Foundation of China(Grant No.51902246,12161141012,and 12174299)the China National Key R&D Program(Grant No.2021YFB3201800 and 2020YFC0122100)+5 种基金the Natural Science Fundamental Research Project of Shaanxi Province of China(No.2019JQ590)the Key R&D Program of Shaanxi Province of China(2020GY-271)the Fundamental Research Funds for the Central Universities(xzd012020059)the“111 Project”of China(B14040)the Natural Sciences&Engineering Research Council of Canada(NSERC,Discovery Grant No.RGPIN-2017-06915)Xijiang Innovation Team Introduction Program of Zhaoqing(Jiecheng).
文摘Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.
基金the National Key Research and Development Program of China(Grant No.2022YFB3807404)the Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents (Grant No. BX2021377 ).
文摘High-piezoelectric properties in lead-free materials have been the pursuit for both industry and scientific research.In this work,the synergistic approaches of phase/domain engineering and novel poling method are adopted for the improvement of piezoelectric performance.The strategically designed lead-free donor-doped BiFeO_(3)-x BaTiO_(3) ceramics at the crystal structure morphotropic phase boundary(MPB)between the rhombohedral and tetragonal phases exhibited a high Curie temperature(T C≥450°C).Furthermore,si-multaneously enhanced static piezoelectric constant(d_(33))of 436±5 pC/N and thermally stable dynamic piezoelectric constant(d_(33)^(∗))of 550±10 pm/V were achieved.The high piezoelectric performance is col-lectively attributed to the crystal structure MPB,thermal quenching effect,local structure heterogeneity induced by donor doping,mesoscale nanodomains,and novel poling method inside a magnetic field.The temperature-insensitive and high piezoelectric performance of the current work is superior to the other lead-free piezoceramics.The synergistic approach for the improvement of piezoelectricity provides a path for the development of lead-free ceramics for high-temperature commercial applications.
