The Experts below are selected from a list of 5661 Experts worldwide ranked by ideXlab platform

Gustau Catalan - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the cellular response to bone fractures evidence for Flexoelectricity
    arXiv: Tissues and Organs, 2020
    Co-Authors: Raquel Nuneztoldra, Nathalie Barroca, Fabian Vasquezsancho, Gustau Catalan
    Abstract:

    The recent discovery of bone Flexoelectricity (electrical polarization induced by strain gradient) suggests that Flexoelectricity could have physiological effects in bones, and specifically near bone fractures, where Flexoelectricity is theoretically highest. Here, we report a cytological study of the interaction between crack stress and bone cells. We have cultured MC3T3-E1 mouse osteoblastic cells in biomimetic microcracked hydroxyapatite substrates, differentiated into osteocytes and applied a strain gradient to the samples. The results show a strong apoptotic cellular response, whereby mechanical stimulation causes those cells near the crack to die, as indicated by live-dead and caspase staining. In addition, analysis two weeks after stimulation shows increased cell attachment and mineralization around microcracks and a higher expression of osteocalcin, an osteogenic protein known to be promoted by physical exercise. The results are consistent with Flexoelectricity playing at least two different roles in bone remodelling: apoptotic trigger of the repair protocol, and electrostimulant of the bone-building activity of osteoblasts.

  • Investigation of The Cellular Response to Bone Fractures: Evidence for Flexoelectricity
    Scientific Reports, 2020
    Co-Authors: Raquel Núñez-toldrà, Fabian Vasquez-sancho, Nathalie Barroca, Gustau Catalan
    Abstract:

    The recent discovery of bone Flexoelectricity (strain-gradient-induced electrical polarization) suggests that Flexoelectricity could have physiological effects in bones, and specifically near bone fractures, where Flexoelectricity is theoretically highest. Here, we report a cytological study of the interaction between crack stress and bone cells. We have cultured MC3T3-E1 mouse osteoblastic cells in biomimetic microcracked hydroxyapatite substrates, differentiated into osteocytes and applied a strain gradient to the samples. The results show a strong apoptotic cellular response, whereby mechanical stimulation causes those cells near the crack to die, as indicated by live-dead and caspase staining. In addition, analysis two weeks post-stimulation shows increased cell attachment and mineralization around microcracks and a higher expression of osteocalcin –an osteogenic protein known to be promoted by physical exercise. The results are consistent with Flexoelectricity playing at least two different roles in bone remodelling: apoptotic trigger of the repair protocol, and electro-stimulant of the bone-building activity of osteoblasts.

  • flexoelectric fracture ratchet effect in ferroelectrics
    Physical Review Letters, 2019
    Co-Authors: Gustau Catalan, Kumara Corderoedwards, Hoda Kianirad, Carlota Canalias, J Sort
    Abstract:

    The propagation front of a crack generates large strain gradients and it is therefore a strong source of gradient-induced polarization (Flexoelectricity). Herein, we demonstrate that, in piezoelectric materials, a consequence of Flexoelectricity is that crack propagation is helped or hindered depending on whether it is parallel or antiparallel to the piezoelectric polar axis. The discovery of crack propagation asymmetry proves that fracture physics cannot be assumed to be symmetric in polar materials, and indicates that Flexoelectricity should be incorporated in any realistic model.

  • Converse Flexoelectricity yields large piezoresponse force microscopy signals in non-piezoelectric materials
    Nature Communications, 2019
    Co-Authors: Amir Abdollahi, Irene Arias, Neus Domingo, Gustau Catalan
    Abstract:

    Piezoresponse force microscopy (PFM) is widely used to study piezoelectric properties of materials. Here, the authors not only show that PFM measurements will yield a signal even in non-piezoelectric materials via induced Flexoelectricity, but also introduce a protocol to distinguish these from real signals. Converse Flexoelectricity is a mechanical stress induced by an electric polarization gradient. It can appear in any material, irrespective of symmetry, whenever there is an inhomogeneous electric field distribution. This situation invariably happens in piezoresponse force microscopy (PFM), which is a technique whereby a voltage is delivered to the tip of an atomic force microscope in order to stimulate and probe piezoelectricity at the nanoscale. While PFM is the premier technique for studying ferroelectricity and piezoelectricity at the nanoscale, here we show, theoretically and experimentally, that large effective piezoelectric coefficients can be measured in non-piezoelectric dielectrics due to converse Flexoelectricity.

  • Piezoelectric Mimicry of Flexoelectricity.
    Physical review letters, 2018
    Co-Authors: Amir Abdollahi, Fabian Vasquez-sancho, Gustau Catalan
    Abstract:

    The origin of ``giant'' Flexoelectricity, orders of magnitude larger than theoretically predicted, yet frequently observed, is under intense scrutiny. There is mounting evidence correlating giant flexoelectriclike effects with parasitic piezoelectricity, but it is not clear how piezoelectricity (polarization generated by strain) manages to imitate Flexoelectricity (polarization generated by strain gradient) in typical beam-bending experiments, since in a bent beam the net strain is zero. In addition piezoelectricity changes sign under space inversion but giant Flexoelectricity is insensitive to space inversion, seemingly contradicting a piezoelectric origin. Here we show that, if a piezoelectric material has its piezoelectric coefficient asymmetrically distributed across the sample, it will generate a nonzero bending-induced polarization impossible to distinguish from true Flexoelectricity even by inverting the sample. The effective flexoelectric coefficient caused by piezoelectricity is functionally identical to, and often larger than, intrinsic Flexoelectricity: our calculations show that, for standard perovskite ferroelectrics, even a tiny gradient of piezoelectricity (1% variation of piezoelectric coefficient across 1 mm) is sufficient to yield a giant effective flexoelectric coefficient of $1\text{ }\text{ }\ensuremath{\mu}\mathrm{C}/\mathrm{m}$, three orders of magnitude larger than the intrinsic expectation value.

Shengping Shen - One of the best experts on this subject based on the ideXlab platform.

  • Diversity of transverse Flexoelectricity in non-poled polyvinylidene fluoride
    Journal of Applied Physics, 2020
    Co-Authors: Shuwen Zhang, Kaiyuan Liu, Shengping Shen
    Abstract:

    As a promising electromechanical effect in dielectric materials, Flexoelectricity describes the linear relation between a strain gradient and its induced electric polarization. Flexoelectricity in polymeric materials is separated from that of crystal dielectrics in both the mechanism and value due to their complicated structures. Independent works reported flexoelectric coefficients of one material as different values, even spanning magnitudes. Curiosity then comes on the exact flexoelectric coefficients of polymeric dielectrics. In this work, diversity of transverse Flexoelectricity in non-poled bulk polyvinylidene fluoride on three geometric dimensionalities is researched and discussed. An obvious diversity of transverse Flexoelectricity is revealed by investigating two transverse flexoelectric coefficient components, which may be induced by pre-existed charges of materials. This work indicates that the flexoelectric response exists in a range in one polymeric material. This result also expands a possibility of applications with Flexoelectricity in polymeric materials and additionally highlights the importance of the mechanism in low-symmetric dielectric solid materials.

  • Flexoelectret: An Electret with a Tunable Flexoelectriclike Response.
    Physical Review Letters, 2019
    Co-Authors: Dongfan Li, Qian Deng, Shengping Shen
    Abstract:

    : Because of the flexoelectric effect, dielectric materials usually polarize in response to a strain gradient. Soft materials are good candidates for developing a large strain gradient because of their good deformability. However, they always suffer from lower flexoelectric coefficients compared to ceramics. In this work, a flexoelectriclike effect is introduced to enhance the effective Flexoelectricity of a polydimethylsiloxane bar. The flexoelectriclike effect is realized by depositing a layer of net charges on the middle plane of the bar to form an electret. Experiments show that the enhancement of Flexoelectricity depends on the density of inserted net charges. It is found that a charged layer with surface potential of -5723  V results in a 100 times increase of the material's flexoelectric coefficient. We also show that the enhancement is proportional to the thickness of electrets. This work provides a new way of enhancing Flexoelectricity in soft materials and further prompts the application of soft materials in electromechanical transducers.

  • lamb wave propagation with Flexoelectricity and strain gradient elasticity considered
    Smart Materials and Structures, 2018
    Co-Authors: Wenjun Yang, Qian Deng, Xu Liang, Shengping Shen
    Abstract:

    In this paper, the effects of Flexoelectricity and strain gradient elasticity on Lamb waves propagating in an infinite piezoelectric nanoplate are analytically investigated. The dispersion equations are obtained and numerically solved for both the electrically open and short cases. A detailed discussion about the dispersion relations of the lowest mode is subsequently presented. Numerical results indicate that Flexoelectricity and strain gradient elasticity have a substantial effect on Lamb wave propagation. Compared with the phase velocity of classical piezoelectric Lamb waves, Flexoelectricity could decrease the phase velocity, while strain gradient elasticity could increase it. The effects of Flexoelectricity and strain gradient elasticity largely depend on the wave number, material properties and nanoplate thickness. In infinite PZT-5H ceramic nanoplates, the effects of Flexoelectricity and strain gradient elasticity on the phase velocity are negligible for wave numbers less than 106 m−1. However, for larger wave numbers, not only the phase velocity but also the dispersion relations can be significantly changed with the introduction of Flexoelectricity and strain gradient elasticity. In addition, the effects of Flexoelectricity and strain gradient elasticity on the electromechanical coupling coefficient are significant and complicated. Since the flexoelectric effect and the strain gradient elasticity effect exist in almost all dielectric materials, the conclusions obtained in this paper are general and can be applied to the analysis and design of the acoustic devices based on Lamb wave propagation.

  • A Three-Dimensional Mixed Finite Element for Flexoelectricity
    Journal of Applied Mechanics, 2018
    Co-Authors: Feng Deng, Qian Deng, Shengping Shen
    Abstract:

    Flexoelectric effect is a universal and size-dependent electromechanical coupling between the strain gradient and electric field. The mathematical framework for Flexoelectricity, which involves higher-order gradients of field quantities, is difficult to handle using traditional finite element method (FEM). Thus, it is important to develop an effective numerical method for Flexoelectricity. In this paper, we develop a three-dimensional (3D) mixed finite element considering both Flexoelectricity and strain gradient elasticity. To validate the developed element, we simulate the electromechanical behavior of a flexoelectric spherical shell subjected to inner pressure and compare the numerical results to analytical results. Their excellent agreement shows the reliability of the proposed FEM. The developed finite element is also used to simulate the electromechanical behavior of a nanometer-sized flexoelectric truncated pyramid. By decreasing the sample size, we observed the increase of its effective piezoelectricity. However, due to the effects of strain gradient elasticity and the influence of Flexoelectricity on stiffness, the dependency of effective piezoelectricity on the sample size is not trivial. Numerical results indicate that, when the sample size is smaller than a certain value, the increase of effective piezoelectricity slows down. This finding also shows the importance of a numerical tool for the study of flexoelectric problems.

  • A curved resonant flexoelectric actuator
    Applied Physics Letters, 2017
    Co-Authors: Shuwen Zhang, Kaiyuan Liu, Shengping Shen
    Abstract:

    Flexoelectricity is an electro-mechanical coupling effect that exists in all dielectrics and has the potential to replace piezoelectric actuating on the microscale. In this letter, a curved flexoelectric actuator with non-polarized polyvinylidene fluoride is presented and shown to exhibit good electro-mechanical properties. This provides experimental support for a body of theoretical research into converse Flexoelectricity in polymeric materials. In addition, this work demonstrates the feasibility of lead-free microscale actuating without piezoelectricity.

Daining Fang - One of the best experts on this subject based on the ideXlab platform.

  • analytical method to determine flexoelectric coupling coefficient at nanoscale
    arXiv: Materials Science, 2016
    Co-Authors: Hao Zhou, Jiawang Hong, Yongmao Pei, Daining Fang
    Abstract:

    Flexoelectricity is defined as the coupling between strain gradient and polarization, which is expected to be remarkable at nanoscale. However, measuring the Flexoelectricity at nanoscale is challenging. In the present work, an analytical method for measuring the flexoelectric coupling coefficient based on nanocompression technique is proposed. It is found that the Flexoelectricity can induce stiffness softening of dielectric nano-cone-frustum. This phenomenon becomes more significant when the sample size decreases or the half cone angle increases. This method avoids measuring the electric polarization or current at nanoscale with dynamical loading, which can be beneficial to the flexoelectric measurement at nanoscale and design of flexoelectric nanodevices.

  • analytical method to determine flexoelectric coupling coefficient at nanoscale
    Applied Physics Letters, 2016
    Co-Authors: Hao Zhou, Jiawang Hong, Daining Fang
    Abstract:

    Flexoelectricity is defined as the coupling between the strain gradient and polarization, which is expected to be remarkable at nanoscale. However, measuring the Flexoelectricity at nanoscale is challenging. In the present work, an analytical method for measuring the flexoelectric coupling coefficient based on nanocompression technique is proposed. It is found that the Flexoelectricity can induce stiffness softening of the dielectric nano-cone-frustum. This phenomenon becomes more significant when the sample size decreases or the half cone angle increases. This method avoids measuring the electric polarization or current at nanoscale with dynamical loading, which can be beneficial to the flexoelectricmeasurement at nanoscale and design of flexoelectric nanodevices.

  • Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films
    Physica B-condensed Matter, 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that Flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO3 thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the Flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

  • external uniform electric field removing flexoelectric effect in epitaxial ferroelectric thin films
    arXiv: Materials Science, 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Using the modified Landau-Ginsburg-Devonshire thermodynamic theory, it is found that the coupling between stress gradient and polarization, or Flexoelectricity, has significant effect on ferroelectric properties of epitaxial thin films, such as polarization, free energy profile and hysteresis loop. However, this effect can be completely eliminated by applying an optimized external, uniform electric field. The role of such uniform electric field is shown to be the same as that of an ideal gradient electric field which can suppress the flexoelectricty effect completely based on the present theory. Since the uniform electric field is more convenient to apply and control than gradient electric field, it can be potentially used to remove the flexoelectric effect induced by stress gradient in epitaxial thin films and enhance the ferroelectric properties.

  • External uniform electric field removing the flexoelectric effect in epitaxial ferroelectric thin films
    EPL (Europhysics Letters), 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Using the modified Landau-Ginzburg-Devonshire thermodynamic theory, it is found that the coupling between stress gradient and polarization, or Flexoelectricity, has a significant effect on ferroelectric properties of epitaxial thin films, such as polarization, free-energy profile and hysteresis loop. However, this effect can be completely eliminated by applying an optimized external, uniform electric field. The role of such uniform electric field is shown to be the same as that of an ideal gradient electric field which can suppress the flexoelectricty effect completely based on the present theory. Since the uniform electric field is more convenient to apply and control than the gradient electric field, it can be potentially used to remove the flexoelectric effect induced by the stress gradient in epitaxial thin films and to enhance the ferroelectric properties.

Liying Jiang - One of the best experts on this subject based on the ideXlab platform.

  • size effects on electromechanical coupling fields of a bending piezoelectric nanoplate due to surface effects and Flexoelectricity
    Journal of Applied Physics, 2014
    Co-Authors: Zhengrong Zhang, Liying Jiang
    Abstract:

    Due to large surface to volume ratio and manifest strain gradients typically present in nanostructures, it is essential to incorporate both surface effects and Flexoelectricity in studying the size-dependent electromechanical coupling behaviors of piezoelectric materials at the nano-scale. In the current work, a modified Kirchhoff plate model with the consideration of residual surface stress, surface elasticity, surface piezoelectricity, and Flexoelectricity is developed to investigate the electroelastic responses and vibrational behaviors of a bending piezoelectric nanoplate (PNP). The governing equations and the corresponding boundary conditions accounting for both the surface effects and the Flexoelectricity are derived by the variational principle. Ritz approximate solutions of the static bending and the free vibration indicate that these nano-scale features are more prominent for thinner plates with smaller thickness. The simulation results also reveal that the influence of the Flexoelectricity and t...

  • size effects on electromechanical coupling fields of a bending piezoelectric nanoplate due to surface effects and Flexoelectricity
    Journal of Applied Physics, 2014
    Co-Authors: Zhengrong Zhang, Liying Jiang
    Abstract:

    Due to large surface to volume ratio and manifest strain gradients typically present in nanostructures, it is essential to incorporate both surface effects and Flexoelectricity in studying the size-dependent electromechanical coupling behaviors of piezoelectric materials at the nano-scale. In the current work, a modified Kirchhoff plate model with the consideration of residual surface stress, surface elasticity, surface piezoelectricity, and Flexoelectricity is developed to investigate the electroelastic responses and vibrational behaviors of a bending piezoelectric nanoplate (PNP). The governing equations and the corresponding boundary conditions accounting for both the surface effects and the Flexoelectricity are derived by the variational principle. Ritz approximate solutions of the static bending and the free vibration indicate that these nano-scale features are more prominent for thinner plates with smaller thickness. The simulation results also reveal that the influence of the Flexoelectricity and the surface effects upon the bending behaviors of the PNP depends on the applied electrical loading and the plate dimensions. Moreover, it is also observed that the frequency tuning of PNP-based nanoresonators by adjusting applied electrical load can be modified by both the Flexoelectricity and the surface effects. The current work is expected to provide increased understanding on the theoretical basis for the design and applications of PNP-based nanodevices.

  • flexoelectric effect on the electroelastic responses and vibrational behaviors of a piezoelectric nanoplate
    Journal of Applied Physics, 2014
    Co-Authors: Zhengrong Zhang, Zhi Yan, Liying Jiang
    Abstract:

    Flexoelectricity, referring to the coupling between electric polarization and strain gradients, is a universal effect in all dielectrics and may become manifest at the nano-scale. The current work aims to investigate the flexoelectric effect on the electroelastic responses and the free vibrational behaviors of a piezoelectric nanoplate (PNP). Based on the conventional Kirchhoff plate theory and the extended linear piezoelectricity theory, the governing equation and the boundary conditions of a clamped PNP with the consideration of the static bulk Flexoelectricity are derived. Ritz approximate solutions of the electroelastic fields and the resonant frequencies demonstrate the size-dependency of the flexoelectric effect, which is more prominent for thinner plates with smaller thickness as expected. Simulation results also indicate that the influence of the Flexoelectricity upon the electroelastic fields of a bending PNP and the transverse vibration of the PNP is sensitive to the plate in-plane dimensions as...

  • flexoelectric effect on the electroelastic responses and vibrational behaviors of a piezoelectric nanoplate
    Journal of Applied Physics, 2014
    Co-Authors: Zhengrong Zhang, Zhi Yan, Liying Jiang
    Abstract:

    Flexoelectricity, referring to the coupling between electric polarization and strain gradients, is a universal effect in all dielectrics and may become manifest at the nano-scale. The current work aims to investigate the flexoelectric effect on the electroelastic responses and the free vibrational behaviors of a piezoelectric nanoplate (PNP). Based on the conventional Kirchhoff plate theory and the extended linear piezoelectricity theory, the governing equation and the boundary conditions of a clamped PNP with the consideration of the static bulk Flexoelectricity are derived. Ritz approximate solutions of the electroelastic fields and the resonant frequencies demonstrate the size-dependency of the flexoelectric effect, which is more prominent for thinner plates with smaller thickness as expected. Simulation results also indicate that the influence of the Flexoelectricity upon the electroelastic fields of a bending PNP and the transverse vibration of the PNP is sensitive to the plate in-plane dimensions as well as the applied electric voltage. Moreover, it is suggested that the possible frequency tuning of a PNP resonator by adjusting applied electrical load warrants the consideration of the Flexoelectricity. This study is claimed to provide a theoretical predicition on the trend of the flexoelectric effect upon the static and dynamic behaviors of a bending PNP, thus sheding light on understanding the underlying physics of electromechanical coupling at the nano-scale to some extent.

  • Effect of Flexoelectricity on the Electromechanical Coupling of Piezoelectric Nanoplates
    Proceedings of the 2015 International Conference on Material Science and Applications, 2014
    Co-Authors: Zhengrong Zhang, Liying Jiang
    Abstract:

    Flexoelectricity is referred as an instantaneous polarization of dielectrics in response to non-uniform strains or strain gradients. Due to the fact that strain gradients are inversely proportional to the feature size of structures, the Flexoelectricity is believed to be significant at the nano-scale. Based on the extended linear piezoelectricity theory, this work attempts to investigate the flexoelectric effect upon the electromechanical coupling of a piezoelectric nanoplate by developing a modified Kirchhoff plate model. Simulation results on the electroelastic fields indicate that the flexoelectric effect is size-dependent, which is more prominent for thinner plates with smaller thickness. It is also observed that the effect of the Flexoelectricity upon the electromechanical coupling of the piezoelectric nanoplate is sensitive to the applied electric voltage. This study aims to establish a further understanding of the flexoelectric effect on the electromechanical coupling of piezoelectric nanomaterials, thus provide guidance for the design and applications of piezoelectric nanostructures.

Hao Zhou - One of the best experts on this subject based on the ideXlab platform.

  • analytical method to determine flexoelectric coupling coefficient at nanoscale
    arXiv: Materials Science, 2016
    Co-Authors: Hao Zhou, Jiawang Hong, Yongmao Pei, Daining Fang
    Abstract:

    Flexoelectricity is defined as the coupling between strain gradient and polarization, which is expected to be remarkable at nanoscale. However, measuring the Flexoelectricity at nanoscale is challenging. In the present work, an analytical method for measuring the flexoelectric coupling coefficient based on nanocompression technique is proposed. It is found that the Flexoelectricity can induce stiffness softening of dielectric nano-cone-frustum. This phenomenon becomes more significant when the sample size decreases or the half cone angle increases. This method avoids measuring the electric polarization or current at nanoscale with dynamical loading, which can be beneficial to the flexoelectric measurement at nanoscale and design of flexoelectric nanodevices.

  • analytical method to determine flexoelectric coupling coefficient at nanoscale
    Applied Physics Letters, 2016
    Co-Authors: Hao Zhou, Jiawang Hong, Daining Fang
    Abstract:

    Flexoelectricity is defined as the coupling between the strain gradient and polarization, which is expected to be remarkable at nanoscale. However, measuring the Flexoelectricity at nanoscale is challenging. In the present work, an analytical method for measuring the flexoelectric coupling coefficient based on nanocompression technique is proposed. It is found that the Flexoelectricity can induce stiffness softening of the dielectric nano-cone-frustum. This phenomenon becomes more significant when the sample size decreases or the half cone angle increases. This method avoids measuring the electric polarization or current at nanoscale with dynamical loading, which can be beneficial to the flexoelectricmeasurement at nanoscale and design of flexoelectric nanodevices.

  • Flexoelectricity induced increase of critical thickness in epitaxial ferroelectric thin films
    Physica B-condensed Matter, 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Flexoelectricity describes the coupling between polarization and strain/stress gradients in insulating crystals. In this paper, using the Landau-Ginsburg-Devonshire phenomenological approach, we found that Flexoelectricity could increase the theoretical critical thickness in epitaxial BaTiO3 thin films, below which the switchable spontaneous polarization vanishes. This increase is remarkable in tensile films while trivial in compressive films due to the electrostriction caused decrease of potential barrier, which can be easily destroyed by the Flexoelectricity, between the ferroelectric state and the paraelectric state in tensile films. In addition, the films are still in a uni-polar state even below the critical thickness due to the flexoelectric effect.

  • external uniform electric field removing flexoelectric effect in epitaxial ferroelectric thin films
    arXiv: Materials Science, 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Using the modified Landau-Ginsburg-Devonshire thermodynamic theory, it is found that the coupling between stress gradient and polarization, or Flexoelectricity, has significant effect on ferroelectric properties of epitaxial thin films, such as polarization, free energy profile and hysteresis loop. However, this effect can be completely eliminated by applying an optimized external, uniform electric field. The role of such uniform electric field is shown to be the same as that of an ideal gradient electric field which can suppress the flexoelectricty effect completely based on the present theory. Since the uniform electric field is more convenient to apply and control than gradient electric field, it can be potentially used to remove the flexoelectric effect induced by stress gradient in epitaxial thin films and enhance the ferroelectric properties.

  • External uniform electric field removing the flexoelectric effect in epitaxial ferroelectric thin films
    EPL (Europhysics Letters), 2012
    Co-Authors: Hao Zhou, Jiawang Hong, Yihui Zhang, Yongmao Pei, Daining Fang
    Abstract:

    Using the modified Landau-Ginzburg-Devonshire thermodynamic theory, it is found that the coupling between stress gradient and polarization, or Flexoelectricity, has a significant effect on ferroelectric properties of epitaxial thin films, such as polarization, free-energy profile and hysteresis loop. However, this effect can be completely eliminated by applying an optimized external, uniform electric field. The role of such uniform electric field is shown to be the same as that of an ideal gradient electric field which can suppress the flexoelectricty effect completely based on the present theory. Since the uniform electric field is more convenient to apply and control than the gradient electric field, it can be potentially used to remove the flexoelectric effect induced by the stress gradient in epitaxial thin films and to enhance the ferroelectric properties.