Sol-gel based soft lithography technique has been developed to pattern a variety of ferroelectric Pb（Zr0.52Ti0.48）O3（PZT） microstructures,with feature size approaching 180 nm and good pattern transfer between the ...Sol-gel based soft lithography technique has been developed to pattern a variety of ferroelectric Pb（Zr0.52Ti0.48）O3（PZT） microstructures,with feature size approaching 180 nm and good pattern transfer between the master mold and patterned films.X-ray diffraction and high-resolution transmission electron microscopy confirm the perovskite structure of the patterned PZT.Piezoresponse force microscopy（PFM） and switching spectroscopy piezoresponse force microscopy（SSPFM） confirm their piezoelectricity and ferroelectricity.Piezoresponse as high as 2.75 nm has been observed,comparable to typical PZT films.The patterned PZT microstructures are promising for a wide range of device applications.展开更多
In this paper we report the leakage current, ferroelectric and piezoelectric properties of the YFe O3 film with hexagonal structure, which was fabricated on Si（111） substrate by a simple sol-gel method. The leakage ...In this paper we report the leakage current, ferroelectric and piezoelectric properties of the YFe O3 film with hexagonal structure, which was fabricated on Si（111） substrate by a simple sol-gel method. The leakage current test shows good characteristics as the leakage current density is 5.4 × 10^-6A/cm^2 under 5 V. The dominant leakage mechanism is found to be an Ohmic behavior at low electric field and space-charge-limited conduction at high electric field region. The P–E measurements show ferroelectric hysteresis loops with small remnant polarization and coercive field at room temperature.The distinct and switchable domain structures on the nanometer scale are observed by piezoresponse force microscopy,which testifies to the ferroelectricity of the YFe O3 film further.展开更多
Relaxor ferroelectrics are one of the mysterious objects of the solid-state physics studied over 50 years.The physical properties of relaxors were mainly assessed by scattering and dielectric methods and revealed the ...Relaxor ferroelectrics are one of the mysterious objects of the solid-state physics studied over 50 years.The physical properties of relaxors were mainly assessed by scattering and dielectric methods and revealed the importance of polarization correlations with the short-range order,so-called polarization nanoscale regions.This paper review recent progress achieved by using piezoresponse force microscopy(PFM)to analyze the spatial distribution of polarization and its evolution with time,temperature,and electricfield for the most popular relaxor family:solid solutions between PbMg_(1/3)Nb_(2/3)O_(3) and PbTiO_(3).The PFM technique has proved to be a powerful tool for the investigation of local properties of relaxors where optical techniques obviously fail because of their lack of resolution.The PFM study of relaxors clearly helps to understand the mechanism of polarization distribution and illustrates the importance of mesoscopic polarization patterns that were until now overlooked by major theories of the relaxor state.展开更多
Research on synthesis,characterization and determination of processing-structure-property relationships of commercially important ferroelectric thin films has been performed.The sol-gel type solution deposition techni...Research on synthesis,characterization and determination of processing-structure-property relationships of commercially important ferroelectric thin films has been performed.The sol-gel type solution deposition technique was applied to produce good quality thin films of Ba_(0.6)Sr_(0.4)TiO_(3)(BST60/40)chemical composition on the stainless steel substrates.The thin films were characterized in terms of their microstructure,crystal structure,phase composition,piezoelectric and dielectric properties.It was found that the BST60/40 thin film adopted the cubic structure at room temperature with an elementary cell parameter a-3:971e8TÅ.Morphology of the thin film surface was studied with Atomic Force Microscopy(AFM).Average roughness of the thin films surface was found(Sa=0:055μm).Piezoresponse Force Microscopy(PFM)was applied for the thin film characterization.Active piezoelectric regions were found in BST60/40 thin film.Therefore,dielectric response measured at room temperature was studied in assumption of piezoelectric electric equivalent circuit.展开更多
Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected...Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected by x-ray diffraction pattern, Raman spectrometer, scanning electron microscopy, and atomic force microscope. The local ferroelectric polarization switching properties of the orthorhombic YFO film were confirmed by piezoresponse force microscopy(PFM) for the first time. The results show that the YFO film deposited on LSMO/LAO possesses orthorhombic structure,with ultra-fine crystal grains and flat surface. The leakage current of the YFO film is 8.39 × 10^(-4) A·cm^(-2) at 2 V,with its leakage mechanism found to be an ohmic behavior. PFM measurements indicate that the YFO film reveals weak ferroelectricity at room temperature and the local switching behavior of ferroelectric domains has been identified. By local poling experiment, polarization reversal in the orthorhombic YFO film at room temperature was further observed.展开更多
Alginate biopolymer from Tropicalgin C302245 was studied by means of piezoresponse force microscopy imaging, scanning electron microscopy, powder X-rays, infrared spectroscopy and computer simulations. Local piezoresp...Alginate biopolymer from Tropicalgin C302245 was studied by means of piezoresponse force microscopy imaging, scanning electron microscopy, powder X-rays, infrared spectroscopy and computer simulations. Local piezoresponse force microscopy images show possible ferroelectric domains detected in the out of plane mode and these results are confirmed by the second harmonic generation analysis. Alginate powder is composed by diatom frustules containing a cristobalite-like compound, amorphous silica and chitin. The experimental results are explained by MM+ and PM3 computer simulations that establish that the self-assembly of the alginate molecules enhance the polarization increasing the molecular collective dipole moment. Alginate molecular properties might open interesting possibilities for organic technological applications.展开更多
Local domain structures of ferroelectrics have been studied extensively using various modes of scanning probes at the nanoscale,including piezoresponse force microscopy(PFM)and Kelvin probe force microscopy(KPFM),thou...Local domain structures of ferroelectrics have been studied extensively using various modes of scanning probes at the nanoscale,including piezoresponse force microscopy(PFM)and Kelvin probe force microscopy(KPFM),though none of these techniques measure the polarization directly,and the fast formation kinetics of domains and screening charges cannot be captured by these quasi-static measurements.In this study,we used charge gradient microscopy(CGM)to image ferroelectric domains of lithium niobate based on current measured during fast scanning,and applied principal component analysis(PCA)to enhance the signal-to-noise ratio of noisy raw data.We found that the CGM signal increases linearly with the scan speed while decreases with the temperature under power-law,consistent with proposed imaging mechanisms of scraping and refilling of surface charges within domains,and polarization change across domain wall.We then,based on CGM mappings,estimated the spontaneous polarization and the density of surface charges with order of magnitude agreement with literature data.The study demonstrates that PCA is a powerful method in imaging analysis of scanning probe microscopy(SPM),with which quantitative analysis of noisy raw data becomes possible.展开更多
The controllable manipulation of polar topological structures(e.g.skyrmion bubble)in ferroelectric materials have been considered as a cornerstone for future programmable nano-electronics.Here,we present the effective...The controllable manipulation of polar topological structures(e.g.skyrmion bubble)in ferroelectric materials have been considered as a cornerstone for future programmable nano-electronics.Here,we present the effective creation and erasure of polar bubble states PbTiO_(3)(PTO)multilayers trigged by mechanical stress and light illumination,respectively.It was found that applying atomic force microscope(AFM)tip force can induced formation of nanoscale bubble domains from the initial monodomain state.Moreover,the created bubble domain can be eliminated by exposure to ultraviolet or infrared light illumination.The above results can be understood by modulation of depolarization screening charges and bias fields,as reflected by scanning Kelvin potential microscopic(SKPM)observations,whereby the flexoelectric effect from the tip force tends to remove the screening charges on top surface and modulate the bias field that favors the formation of bubble state while light illumination tends to recover the screen charges and favor the monodomain state.The results provide a good example for multi-field manipulation of polar topologies,which might create a new avenue towards the immerging new concept electronic devices.展开更多
Polarization switching in lead-free(K0.40Na0.60)NbO3(KNN)single crystals was studied by switching spectroscopy piezoresponse force microscopy(SS-PFM).Acquisition of multiple hysteresis loops on a closely spaced square...Polarization switching in lead-free(K0.40Na0.60)NbO3(KNN)single crystals was studied by switching spectroscopy piezoresponse force microscopy(SS-PFM).Acquisition of multiple hysteresis loops on a closely spaced square grid enables polarization switching parameters to be mapped in real space.Piezoresponse amplitude and phase hysteresis loops show collective symmetric/asymmetric characteristics,affording information regarding the switching behavior of different domains.As such,the out-of-plane polarization states of the domains,including amplitudes and phases can be determined.Our results could contribute to a further understanding of the relationships between polarization switching and polarization vectors at the nanoscale,and provide a feasible method to correlate the polarization hysteresis loops in a domain under an electric field with the polarization vector states.展开更多
BiFeO_(3),a room-temperature multiferroic material,has recently been increasingly applied as a potential lead-free piezoelectric material due to its large piezoelectricity achieved by doping.In this work,12%Smdoped Bi...BiFeO_(3),a room-temperature multiferroic material,has recently been increasingly applied as a potential lead-free piezoelectric material due to its large piezoelectricity achieved by doping.In this work,12%Smdoped BiFeO_(3)epitaxial thin films were fabricated on Nb-doped SrTiO_(3)(001)single crystal substrates via sol-gel method.The epitaxy was verified by reciprocal space mapping(RSM)and transmission electron microscope(TEM).The TEM results indicated the coexistence of R3c and Pbam phases in the film.The domains and piezoelectric properties from room temperature to 200℃were characterized by piezoresponse force microscopy(PFM).Domains became active from 110℃to 170℃,and domain configurations changed obviously.A partially fading piezoresponse indicated the emergence of antiferroelectric Pbam.The in-situ domain analysis suggested that the phase transition was accompanied by domain wall motion.Switching spectroscopy PFM(SS-PFM)was further conducted to investigate the piezoresponse during the phase transition.Anomalous responses were found in both ON and OFF states at 170℃,and the film exhibits typical antiferroelectric behavior at 200℃,implying that the completion of phase transition and structure turned to the Pbam phase.This work revealed the origin of the high piezoresponse of Sm-doped BiFeO_(3)thin films at the morphotropic phase boundary(MPB).展开更多
There have been overwhelming observations of piezo-/ferroelectric phenomena in many biological tissues and macromolecules,boosting the development of bio-based smart devices and the applications using electromechanica...There have been overwhelming observations of piezo-/ferroelectric phenomena in many biological tissues and macromolecules,boosting the development of bio-based smart devices and the applications using electromechanical coupling phenomena in biological systems.The electromechanical coupling is believed to be responsible for various biophysical behaviors and remarkable biomaterial properties.Despite the abundant phenomenal observations,the fundamental understanding of the piezo-/ferroelectric effect in biomaterials/systems and the rational design of biobased macroscopic materials with desired piezoelectric responses are still scarce.In this review,we firstly present remarkable historical events on the development of piezo-/ferroelectricity in biomaterials,followed by a brief overview of the fundamental physics of piezo-/ferroelectricity.The developments of biopiezo-/bioferroelectricity in protein-based biomaterials and their implications are highlighted subsequently.In experimental studies,to identify the intrinsic piezo-/ferroelectric properties from other effects or artifacts is usually elusive.This issue is also addressed and discussed in detail,especially using piezoelectric force microscopy(PFM)and spectroscopy techniques to investigate the local piezo-/ferroelectric phenomena in nanostructured materials are highlighted emphatically.展开更多
基金support from National Natural Science Foundation of China (Grant Nos. 10772155,10732100 and 10902095)the Provincial Natural Science Foundation of Hunan Province, China (Grant Nos.07JJ1008 and 09JJ7004)+2 种基金the Scientific Research Fund of Hunan Provincial Education Department (Grant No.08C864)The Asylum Research MFP-3D Atomic Force Microscope was acquired through an ARO DURIP grant(W911NF-08-01-0262)support from US National Science Foundation (DMR 0706100 and OS)
文摘Sol-gel based soft lithography technique has been developed to pattern a variety of ferroelectric Pb（Zr0.52Ti0.48）O3（PZT） microstructures,with feature size approaching 180 nm and good pattern transfer between the master mold and patterned films.X-ray diffraction and high-resolution transmission electron microscopy confirm the perovskite structure of the patterned PZT.Piezoresponse force microscopy（PFM） and switching spectroscopy piezoresponse force microscopy（SSPFM） confirm their piezoelectricity and ferroelectricity.Piezoresponse as high as 2.75 nm has been observed,comparable to typical PZT films.The patterned PZT microstructures are promising for a wide range of device applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61471301,61078057,51202195,and 511172183)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20126102110045)the NPU Foundation for Fundamental Research(Grant Nos.JC201155,JC201271,and JC20120246)
文摘In this paper we report the leakage current, ferroelectric and piezoelectric properties of the YFe O3 film with hexagonal structure, which was fabricated on Si（111） substrate by a simple sol-gel method. The leakage current test shows good characteristics as the leakage current density is 5.4 × 10^-6A/cm^2 under 5 V. The dominant leakage mechanism is found to be an Ohmic behavior at low electric field and space-charge-limited conduction at high electric field region. The P–E measurements show ferroelectric hysteresis loops with small remnant polarization and coercive field at room temperature.The distinct and switchable domain structures on the nanometer scale are observed by piezoresponse force microscopy,which testifies to the ferroelectricity of the YFe O3 film further.
文摘Relaxor ferroelectrics are one of the mysterious objects of the solid-state physics studied over 50 years.The physical properties of relaxors were mainly assessed by scattering and dielectric methods and revealed the importance of polarization correlations with the short-range order,so-called polarization nanoscale regions.This paper review recent progress achieved by using piezoresponse force microscopy(PFM)to analyze the spatial distribution of polarization and its evolution with time,temperature,and electricfield for the most popular relaxor family:solid solutions between PbMg_(1/3)Nb_(2/3)O_(3) and PbTiO_(3).The PFM technique has proved to be a powerful tool for the investigation of local properties of relaxors where optical techniques obviously fail because of their lack of resolution.The PFM study of relaxors clearly helps to understand the mechanism of polarization distribution and illustrates the importance of mesoscopic polarization patterns that were until now overlooked by major theories of the relaxor state.
基金The present research was supported by National Science Centre,Poland,as a re-search project No.N50709831/2319.
文摘Research on synthesis,characterization and determination of processing-structure-property relationships of commercially important ferroelectric thin films has been performed.The sol-gel type solution deposition technique was applied to produce good quality thin films of Ba_(0.6)Sr_(0.4)TiO_(3)(BST60/40)chemical composition on the stainless steel substrates.The thin films were characterized in terms of their microstructure,crystal structure,phase composition,piezoelectric and dielectric properties.It was found that the BST60/40 thin film adopted the cubic structure at room temperature with an elementary cell parameter a-3:971e8TÅ.Morphology of the thin film surface was studied with Atomic Force Microscopy(AFM).Average roughness of the thin films surface was found(Sa=0:055μm).Piezoresponse Force Microscopy(PFM)was applied for the thin film characterization.Active piezoelectric regions were found in BST60/40 thin film.Therefore,dielectric response measured at room temperature was studied in assumption of piezoelectric electric equivalent circuit.
基金supported by the National Natural Science Foundation of China(Grant No.61471301)Natural Science Basic Research Program of Shaanxi,China(Grant No.2017JQ5083)PhD Research Startup Foundation of Xi’an University of Science and Technology,China(Grant No.2017QDJ044)
文摘Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected by x-ray diffraction pattern, Raman spectrometer, scanning electron microscopy, and atomic force microscope. The local ferroelectric polarization switching properties of the orthorhombic YFO film were confirmed by piezoresponse force microscopy(PFM) for the first time. The results show that the YFO film deposited on LSMO/LAO possesses orthorhombic structure,with ultra-fine crystal grains and flat surface. The leakage current of the YFO film is 8.39 × 10^(-4) A·cm^(-2) at 2 V,with its leakage mechanism found to be an ohmic behavior. PFM measurements indicate that the YFO film reveals weak ferroelectricity at room temperature and the local switching behavior of ferroelectric domains has been identified. By local poling experiment, polarization reversal in the orthorhombic YFO film at room temperature was further observed.
文摘Alginate biopolymer from Tropicalgin C302245 was studied by means of piezoresponse force microscopy imaging, scanning electron microscopy, powder X-rays, infrared spectroscopy and computer simulations. Local piezoresponse force microscopy images show possible ferroelectric domains detected in the out of plane mode and these results are confirmed by the second harmonic generation analysis. Alginate powder is composed by diatom frustules containing a cristobalite-like compound, amorphous silica and chitin. The experimental results are explained by MM+ and PM3 computer simulations that establish that the self-assembly of the alginate molecules enhance the polarization increasing the molecular collective dipole moment. Alginate molecular properties might open interesting possibilities for organic technological applications.
基金National Key Research and Development Program of China(2016YFA0201001)US National Science Foundation(CBET-1435968)+1 种基金National Natural Science Foundation of China(11627801,11472236 and 51472037)This material is based in part upon work supported by the State of Washington through the University of Washington Clean Energy Institute.
文摘Local domain structures of ferroelectrics have been studied extensively using various modes of scanning probes at the nanoscale,including piezoresponse force microscopy(PFM)and Kelvin probe force microscopy(KPFM),though none of these techniques measure the polarization directly,and the fast formation kinetics of domains and screening charges cannot be captured by these quasi-static measurements.In this study,we used charge gradient microscopy(CGM)to image ferroelectric domains of lithium niobate based on current measured during fast scanning,and applied principal component analysis(PCA)to enhance the signal-to-noise ratio of noisy raw data.We found that the CGM signal increases linearly with the scan speed while decreases with the temperature under power-law,consistent with proposed imaging mechanisms of scraping and refilling of surface charges within domains,and polarization change across domain wall.We then,based on CGM mappings,estimated the spontaneous polarization and the density of surface charges with order of magnitude agreement with literature data.The study demonstrates that PCA is a powerful method in imaging analysis of scanning probe microscopy(SPM),with which quantitative analysis of noisy raw data becomes possible.
基金the financial support from the National Key Research and Development Programs of China(Grant Nos.2022YFB3807603)National Natural Science Foundation of China(Grant Nos.92163210,11674108,52002134,U22A20117)+2 种基金Funding by Science and Technology Projects in Guangzhou(202201000008)the Science and Technology Planning Project of Guangdong Province(No.2019KQNCX028)the Natural Science Foundation of South China Normal University(No.19KJ01).
文摘The controllable manipulation of polar topological structures(e.g.skyrmion bubble)in ferroelectric materials have been considered as a cornerstone for future programmable nano-electronics.Here,we present the effective creation and erasure of polar bubble states PbTiO_(3)(PTO)multilayers trigged by mechanical stress and light illumination,respectively.It was found that applying atomic force microscope(AFM)tip force can induced formation of nanoscale bubble domains from the initial monodomain state.Moreover,the created bubble domain can be eliminated by exposure to ultraviolet or infrared light illumination.The above results can be understood by modulation of depolarization screening charges and bias fields,as reflected by scanning Kelvin potential microscopic(SKPM)observations,whereby the flexoelectric effect from the tip force tends to remove the screening charges on top surface and modulate the bias field that favors the formation of bubble state while light illumination tends to recover the screen charges and favor the monodomain state.The results provide a good example for multi-field manipulation of polar topologies,which might create a new avenue towards the immerging new concept electronic devices.
基金This work was supported by Science Challenge Project(No.TZ2018003)National Natural Science Foundation of China(Grant Nos.51822206 and 5171101344).
文摘Polarization switching in lead-free(K0.40Na0.60)NbO3(KNN)single crystals was studied by switching spectroscopy piezoresponse force microscopy(SS-PFM).Acquisition of multiple hysteresis loops on a closely spaced square grid enables polarization switching parameters to be mapped in real space.Piezoresponse amplitude and phase hysteresis loops show collective symmetric/asymmetric characteristics,affording information regarding the switching behavior of different domains.As such,the out-of-plane polarization states of the domains,including amplitudes and phases can be determined.Our results could contribute to a further understanding of the relationships between polarization switching and polarization vectors at the nanoscale,and provide a feasible method to correlate the polarization hysteresis loops in a domain under an electric field with the polarization vector states.
基金This work was supported by the National Nature Science Foundation of China(Grants no.51332002,11374174,51390471,51527803 and 51221291)the Ministry of Science and Technology of China under Grant 2015CB654605,National 973 Project of China(2015CB654902)+1 种基金National key research and development program(2016YFB0700402)This work made use of the resources of the National Center for Electron Microscopy in Beijing and the BL14B1 beamline of the Shanghai Synchrotron Radiation Facility under project no.14SRBL14B10499.
文摘BiFeO_(3),a room-temperature multiferroic material,has recently been increasingly applied as a potential lead-free piezoelectric material due to its large piezoelectricity achieved by doping.In this work,12%Smdoped BiFeO_(3)epitaxial thin films were fabricated on Nb-doped SrTiO_(3)(001)single crystal substrates via sol-gel method.The epitaxy was verified by reciprocal space mapping(RSM)and transmission electron microscope(TEM).The TEM results indicated the coexistence of R3c and Pbam phases in the film.The domains and piezoelectric properties from room temperature to 200℃were characterized by piezoresponse force microscopy(PFM).Domains became active from 110℃to 170℃,and domain configurations changed obviously.A partially fading piezoresponse indicated the emergence of antiferroelectric Pbam.The in-situ domain analysis suggested that the phase transition was accompanied by domain wall motion.Switching spectroscopy PFM(SS-PFM)was further conducted to investigate the piezoresponse during the phase transition.Anomalous responses were found in both ON and OFF states at 170℃,and the film exhibits typical antiferroelectric behavior at 200℃,implying that the completion of phase transition and structure turned to the Pbam phase.This work revealed the origin of the high piezoresponse of Sm-doped BiFeO_(3)thin films at the morphotropic phase boundary(MPB).
基金supported by the Ministry of Education (Singapore) through the National University of Singapore under the Academic Research Grant (ACRF) (Grant Nos. R-265-000-495-112, and R-265-000-596-112)financial support from the National Key Research and Development Program of China (Grant Nos. 2018YFB0407600, 2017YFA0206202, and 2016YFA0300702)+1 种基金the National Natural Science Foundation of China (Grant No. 51802250)the Key Research and Development Program of Shaanxi (Grant No. 2019TSLGY0804)
文摘There have been overwhelming observations of piezo-/ferroelectric phenomena in many biological tissues and macromolecules,boosting the development of bio-based smart devices and the applications using electromechanical coupling phenomena in biological systems.The electromechanical coupling is believed to be responsible for various biophysical behaviors and remarkable biomaterial properties.Despite the abundant phenomenal observations,the fundamental understanding of the piezo-/ferroelectric effect in biomaterials/systems and the rational design of biobased macroscopic materials with desired piezoelectric responses are still scarce.In this review,we firstly present remarkable historical events on the development of piezo-/ferroelectricity in biomaterials,followed by a brief overview of the fundamental physics of piezo-/ferroelectricity.The developments of biopiezo-/bioferroelectricity in protein-based biomaterials and their implications are highlighted subsequently.In experimental studies,to identify the intrinsic piezo-/ferroelectric properties from other effects or artifacts is usually elusive.This issue is also addressed and discussed in detail,especially using piezoelectric force microscopy(PFM)and spectroscopy techniques to investigate the local piezo-/ferroelectric phenomena in nanostructured materials are highlighted emphatically.
