The effects of calcined lead--zirconate-titanate(PZT)powders on the electric properties of PZT/polyvinylidene-tifluorethylene copolymer(PVDF-TrFE)composites thick films were studied in this paper.Firstly,the PZT powde...The effects of calcined lead--zirconate-titanate(PZT)powders on the electric properties of PZT/polyvinylidene-tifluorethylene copolymer(PVDF-TrFE)composites thick films were studied in this paper.Firstly,the PZT powders synthesized by hydrothermal method were calcined at different temperatures ranging from 300℃ to 900℃,and then the PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the indium-tin-oxide(ITO)-coated glass substrates.Electric properties,including dielectric and pyroelectric performances of thick films consisting of PZT powders calcined at different temperatures were tested.The highest pyroelectric cofficient obtained in the sample using 700℃ calcined PZT powders was 96μCm^(-2)K^(-1),which was 20%higher than the composites made of uncalcined powders.Additionally,the highest detectivity figure-of merit(FOM)(FD)of the composite was 1.36×10^(-5)Pa^(-1/2),which increased about 13.5%compared to the one using uncalcined powders.展开更多
The emerging interfacial polarization strategy exhibits applicative potential in piezoelectric enhancement.However,there is an ongoing effort to address the inherent limitations arising from charge bridging phenomena ...The emerging interfacial polarization strategy exhibits applicative potential in piezoelectric enhancement.However,there is an ongoing effort to address the inherent limitations arising from charge bridging phenomena and stochastic interface disorder that plague the improvement of piezoelectric performance.Here,we report a dual structure reinforced MXene/PVDF-TrFE piezoelectric composite,whose piezoelectricity is enhanced under the coupling effect of interfacial polarization and structural design.Synergistically,molecular dynamics simulations,density functional theory calculations and experimental validation revealed the details of interfacial interactions,which promotes the net spontaneous polarization of PVDF-TrFE from the 0.56 to 31.41 Debye.The oriented MXene distribution and porous structure not only tripled the piezoelectric response but also achieved an eightfold increase in sensitivity within the low-pressure region,along with demonstrating cyclic stability exceeding 20,000 cycles.The properties reinforcement originating from dual structure is elucidated through the finite element simulation and experimental validation.Attributed to the excellent piezoelectric response and deep learning algorithm,the sensor can effectively recognize the signals of artery pulse and finger flexion.Finally,a 3×3 sensor array is fabricated to monitor the pressure distribution wirelessly.This study provides an innovative methodology for reinforcing interfacial polarized piezoelectric materials and insight into structural designs.展开更多
Lead zirconate titanate(PbZr_(x)Ti_(1-x)O_(3),PZT)ferroelectric films possess remarkable characteristics such as high residual polarization,high dielectric constant,and high piezoelectric coefficient and have great ap...Lead zirconate titanate(PbZr_(x)Ti_(1-x)O_(3),PZT)ferroelectric films possess remarkable characteristics such as high residual polarization,high dielectric constant,and high piezoelectric coefficient and have great application prospects in modern electronics,communications,medical care,and military fields.At present,the microstructure changes of PZT ferroelectric thin films have a significant impact on their electrical properties.Therefore,this work summarizes the influences of geometric structure(thickness,porosity),composition structure(Zr/Ti ratio,doping),and grain structure(grain size,grain boundaries,orientation)on the electrical properties of PZT ferroelectric thin films.The results show that the changes in thickness and porosity have a significant impact on the electrical properties of PZT ferroelectric films.Especially,the actual application scenarios and preparation processes determine the required geometric dimensions and structures of PZT ferroelectric films.The Zr/Ti ratio and doping mainly affect the electrical properties by influencing the phase composition of PZT ferroelectric films.The changes in grain size,boundary structure,and orientation dependence mainly have a certain degree of influence on the domain response and domain switching behavior of PZT ferroelectric thin films.In conclusion,different structures have different influence effects on the dielectric,ferroelectric,and piezoelectric properties of PZT ferroelectric films.The way the tiny structure affects how PZT thin films work was shown,helping to guide the design of ferroelectric thin film devices.In order to further study and apply piezoelectric ceramic devices,it is crucial to have an in-depth understanding of the relationship between the structure and performance of piezoelectric ceramic devices.展开更多
Insect-scale flapping wing aerial robots actuated by piezoelectric materials—known for their high power density and rapid frequency response—have recently garnered increasing attention.However,the limited output dis...Insect-scale flapping wing aerial robots actuated by piezoelectric materials—known for their high power density and rapid frequency response—have recently garnered increasing attention.However,the limited output displacement of piezoelectric actuators results in complex transmission methods that are challenging to assemble.Furthermore,high piezoelectric coefficient materials capable of large displacements for direct wing actuation are fragile,costly,and relatively bulky.This article presents a novel design for minimalist insect-scale aerial robots,where piezoelectric bimorph PZT actuators directly drive two pairs of wings,thus eliminating complex transmission mechanisms and reducing fabrication complexity.These robots demonstrate high liftoff speeds and favorable lift-to-weight ratios,and they can achieve vertical ascent under uncontrolled open-loop conditions.The piezoelectric direct-driven twowing insect-scale aerial robot,based on this approach,features an 8 cm wingspan and a prototype weight of 140 mg,successfully achieving takeoff under unconstrained conditions with an external power source.To further enhance insect-scale aerial robot performance,we optimized the wing-to-actuator ratio and wing arrangement.We propose a biaxial aerial robot with an X-shaped structure,a 2:1 wing-toactuator ratio,a 70 mm wingspan,and a total mass of 160 mg.This structure demonstrates a high lift-to-weight ratio of 2.8:1.During free flight,when powered externally,it attains a maximum takeoff speed exceeding 1 m/s and achieves a vertical takeoff height surpassing 80 cm under uncontrolled conditions.Consequently,it ranks among the fastest prototypes in the milligram-scale weight category.展开更多
Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were system...Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were systematically investigated.The composite films were characterized by scanning electron microscope(SEM),X-ray diffractometer(XRD),Flourier transform infrared spectroscope(FTIR)and differential scanning calorimeter(DSC).The results show that,surface modified PZT powder(PZT@PDA)is successfully coated by polydopamine(PDA),resulting in a large number of polar groups that interact with the-CF_(2)-groups in PVDF,inducing the generation of polarβphase due to hydrogen bonding formed in the interaction.Theβphase content in composite film increases with increasing PZT@PDA content,up to 28.09%as with 5 wt.%PZT@PDA.PZT@PDA plays a role of nucleating agent to promote the generation of polar phases in the film and also acts as an impurity hindering the growth of nuclei to reduce crystallinity.Moreover,the presence of PZT@PDA in interfaces provides more sites for the occurrence of interfacial polarization and thus improving the electrical properties of films.The composite film with 5 wt.%PZT@PDA possesses the highest dielectric constant(8.61)and residual polarization value(0.6803μC/cm^(2)).展开更多
基金supported by the National Natural Science Foundation of China(NSFC.51102037)the Fundamental Research Funds for the Central Universities from UESTC(No.ZYGX2010J030 and No.ZYGX2011J023).
文摘The effects of calcined lead--zirconate-titanate(PZT)powders on the electric properties of PZT/polyvinylidene-tifluorethylene copolymer(PVDF-TrFE)composites thick films were studied in this paper.Firstly,the PZT powders synthesized by hydrothermal method were calcined at different temperatures ranging from 300℃ to 900℃,and then the PZT/PVDF-TrFE composites films were produced by casting PZT/PVDF-TrFE suspension onto the indium-tin-oxide(ITO)-coated glass substrates.Electric properties,including dielectric and pyroelectric performances of thick films consisting of PZT powders calcined at different temperatures were tested.The highest pyroelectric cofficient obtained in the sample using 700℃ calcined PZT powders was 96μCm^(-2)K^(-1),which was 20%higher than the composites made of uncalcined powders.Additionally,the highest detectivity figure-of merit(FOM)(FD)of the composite was 1.36×10^(-5)Pa^(-1/2),which increased about 13.5%compared to the one using uncalcined powders.
基金supported by the National Natural Science Foundation of China(No.52303328)the Postdoctoral Innovation Talents Support Program(No.BX20220257)the Sichuan Science and Technology Program(No.2023NSFSC0313).
文摘The emerging interfacial polarization strategy exhibits applicative potential in piezoelectric enhancement.However,there is an ongoing effort to address the inherent limitations arising from charge bridging phenomena and stochastic interface disorder that plague the improvement of piezoelectric performance.Here,we report a dual structure reinforced MXene/PVDF-TrFE piezoelectric composite,whose piezoelectricity is enhanced under the coupling effect of interfacial polarization and structural design.Synergistically,molecular dynamics simulations,density functional theory calculations and experimental validation revealed the details of interfacial interactions,which promotes the net spontaneous polarization of PVDF-TrFE from the 0.56 to 31.41 Debye.The oriented MXene distribution and porous structure not only tripled the piezoelectric response but also achieved an eightfold increase in sensitivity within the low-pressure region,along with demonstrating cyclic stability exceeding 20,000 cycles.The properties reinforcement originating from dual structure is elucidated through the finite element simulation and experimental validation.Attributed to the excellent piezoelectric response and deep learning algorithm,the sensor can effectively recognize the signals of artery pulse and finger flexion.Finally,a 3×3 sensor array is fabricated to monitor the pressure distribution wirelessly.This study provides an innovative methodology for reinforcing interfacial polarized piezoelectric materials and insight into structural designs.
基金Supported by National Natural Science Foundation of China(Grant No.55275227)。
文摘Lead zirconate titanate(PbZr_(x)Ti_(1-x)O_(3),PZT)ferroelectric films possess remarkable characteristics such as high residual polarization,high dielectric constant,and high piezoelectric coefficient and have great application prospects in modern electronics,communications,medical care,and military fields.At present,the microstructure changes of PZT ferroelectric thin films have a significant impact on their electrical properties.Therefore,this work summarizes the influences of geometric structure(thickness,porosity),composition structure(Zr/Ti ratio,doping),and grain structure(grain size,grain boundaries,orientation)on the electrical properties of PZT ferroelectric thin films.The results show that the changes in thickness and porosity have a significant impact on the electrical properties of PZT ferroelectric films.Especially,the actual application scenarios and preparation processes determine the required geometric dimensions and structures of PZT ferroelectric films.The Zr/Ti ratio and doping mainly affect the electrical properties by influencing the phase composition of PZT ferroelectric films.The changes in grain size,boundary structure,and orientation dependence mainly have a certain degree of influence on the domain response and domain switching behavior of PZT ferroelectric thin films.In conclusion,different structures have different influence effects on the dielectric,ferroelectric,and piezoelectric properties of PZT ferroelectric films.The way the tiny structure affects how PZT thin films work was shown,helping to guide the design of ferroelectric thin film devices.In order to further study and apply piezoelectric ceramic devices,it is crucial to have an in-depth understanding of the relationship between the structure and performance of piezoelectric ceramic devices.
基金supported by the National Natural Science Foundation of China(No.52475039)。
文摘Insect-scale flapping wing aerial robots actuated by piezoelectric materials—known for their high power density and rapid frequency response—have recently garnered increasing attention.However,the limited output displacement of piezoelectric actuators results in complex transmission methods that are challenging to assemble.Furthermore,high piezoelectric coefficient materials capable of large displacements for direct wing actuation are fragile,costly,and relatively bulky.This article presents a novel design for minimalist insect-scale aerial robots,where piezoelectric bimorph PZT actuators directly drive two pairs of wings,thus eliminating complex transmission mechanisms and reducing fabrication complexity.These robots demonstrate high liftoff speeds and favorable lift-to-weight ratios,and they can achieve vertical ascent under uncontrolled open-loop conditions.The piezoelectric direct-driven twowing insect-scale aerial robot,based on this approach,features an 8 cm wingspan and a prototype weight of 140 mg,successfully achieving takeoff under unconstrained conditions with an external power source.To further enhance insect-scale aerial robot performance,we optimized the wing-to-actuator ratio and wing arrangement.We propose a biaxial aerial robot with an X-shaped structure,a 2:1 wing-toactuator ratio,a 70 mm wingspan,and a total mass of 160 mg.This structure demonstrates a high lift-to-weight ratio of 2.8:1.During free flight,when powered externally,it attains a maximum takeoff speed exceeding 1 m/s and achieves a vertical takeoff height surpassing 80 cm under uncontrolled conditions.Consequently,it ranks among the fastest prototypes in the milligram-scale weight category.
基金Project(22020JJ4729)supported by the Natural Science Foundation of Hunan Province,China。
文摘Polyvinylidene fluoride/lead zirconate titanate(PVDF/PZT)composite films have been prepared by direct ink writing and the effect of PZT content on crystallization behavior and electrical properties of film were systematically investigated.The composite films were characterized by scanning electron microscope(SEM),X-ray diffractometer(XRD),Flourier transform infrared spectroscope(FTIR)and differential scanning calorimeter(DSC).The results show that,surface modified PZT powder(PZT@PDA)is successfully coated by polydopamine(PDA),resulting in a large number of polar groups that interact with the-CF_(2)-groups in PVDF,inducing the generation of polarβphase due to hydrogen bonding formed in the interaction.Theβphase content in composite film increases with increasing PZT@PDA content,up to 28.09%as with 5 wt.%PZT@PDA.PZT@PDA plays a role of nucleating agent to promote the generation of polar phases in the film and also acts as an impurity hindering the growth of nuclei to reduce crystallinity.Moreover,the presence of PZT@PDA in interfaces provides more sites for the occurrence of interfacial polarization and thus improving the electrical properties of films.The composite film with 5 wt.%PZT@PDA possesses the highest dielectric constant(8.61)and residual polarization value(0.6803μC/cm^(2)).
