Possible piezoelectric composites based on the flexoelectric effect

Fousek, J.; Cross, L. E.; Литвин, Д. Б.

doi:10.1016/s0167-577x(99)00020-8

Cited by 143 publications

(86 citation statements)

References 3 publications

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“…This suggests a growth-induced alteration in polarization [25], a phenomenon that is commonly associated with internal strain in the pull direction [12]. In specific perovskites this is known to cause the flexoelectric effect, i.e., a macroscopic strain-induced spontaneous polarization which produces the coupling between the strain gradient and polarization [49][50][51]. Because in a disordered ferroelectric, the strains are inversely proportional to the size of the polar regions [12,52,53], which are nanometric in our case, and the susceptibility has very high values ( ∼ 10 4 and more), we expect this effect be relevant.…”

Section: A Permittivity Anisotropymentioning

confidence: 99%

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

et al. 2016

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Using temperature-resolved dielectric spectroscopy in the range 25-320 K we investigate the macroscopic response, phase symmetry, and order/disorder states in bulk ferroelectric K 1−y Li y Ta 1−x Nb x (KLTN). Four longrange symmetry phases are identified with their relative transitions. Directional analysis of the order/disorder states using Fröhlich entropy indicates global symmetry breaking along the growth axis and an anisotropic dipolar effective thermodynamic behavior, which ranges from disordered to ordered at the same temperature for different directions in the sample. Results indicate that the macroscopic polarization, driven by nanosized polar regions, follows a microscopic perovskite eight-sites lattice model.

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Section: A Permittivity Anisotropymentioning

confidence: 99%

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

et al. 2016

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“…Maranganti et al [17], reviewing this subject, developed a complete mathematical framework for flexoelectricity. Fousek et al [18] first proposed the possibility of fabricating piezoelectric nanocomposite without using piezoelectric materials, while Sharma et al [19] computationally analyzed this nanocomposite. Majdoub et al [20] argue that flexoelectricity exhibits a size effect and has a significant impact on the apparent piezoelectric and elastic behavior of nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Variational principles and governing equations in nano-dielectrics with the flexoelectric effect

Shen

2010

Sci. China Phys. Mech. Astron.

137

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The flexoelectric effect is very strong and coupled with large strain gradients for nanoscale dielectrics. At the nanoscale, the electrostatic force cannot be ignored. In this paper, we have established the electric enthalpy variational principle for nanosized dielectrics with the strain gradient and the polarization gradient effect, as well as the effect of the electrostatic force. The complete governing equations, which include the effect of the electrostatic force, are derived from this variational principle, and based on the principle the generalized electrostatic stress is obtained, the generalized electrostatic stress contains the Maxwell stress corresponding to the polarization and strain, and stress related to the polarization gradient and strain gradient. This work provides the basis for the analysis and computations for the electromechanical problems in nanosized dielectric materials. flexoelectric effect, variational principle, governing equations, dielectrics, electrostatic stress, nanoscale PACS: 46.05.+b, 46.25.Hf, 62.25.+g, 68.35.Md

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“…As shown in Table 1, flexoelectric response in ferroelectrics [5][6][7][8][9][10] is much greater than those in simple dielectrics [1][2][3]23], the measured µ 12 coefficients at 25 °C range from 3.4 µC/m for PbMg 1/3 Nb 2/3 O 3 (PMN) to 76.5 µC/m for Ba 0.67 Sr 0.33 TiO 3 (BST), as a comparison, the coefficients for simple dielectrics are only of the order of 10 -10 C/m. Based on direct flexoelectricity, novel piezoelectric composites might be developed, where all the components are non-piezoelectric, but external mechanical loading leads to strain gradients that result in electric polarization in the properly-shaped components [24]. Recently, by using BST [7], the best flexoelectrics known up to date as building blocks for a dielectric-air binary composite, initial experiment [25] demonstrated the feasibility, although higher response is expected when high strain gradients become available at smaller dimensions.…”

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confidence: 99%

A study of flexoelectric coupling associated internal electric field and stress in thin film ferroelectrics

Ma¹

2008

Physica Status Solidi (b)

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By discussions in the framework of tensor representations and phenomenological theory, general piezoelectricity equations that incorporate direct and inverse flexoelectric effects were analyzed and interlink between direct and inverse flexoelectricity discovered. Due to flexoelectric coupling, mechanical strain gradient is equivalent to internal electric field. In ferroelectrics above the Curie temperature, it was shown theoretically that strain gradient associated electric field leads to non‐zero polarization without external electric field. It was also shown theoretically that polarization (or electric field) gradient is an extra source of internal stress. Magnitudes of flexoelectricity associated internal electric field and stress were analyzed for heteroepitaxial thin films of barium strontium titanate. Flexoelectric coupling is expected to intensify with reducing lateral dimensions and thickness and get large enough at nanoscale to modify ferroelectric phase transitions and functional response. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Possible piezoelectric composites based on the flexoelectric effect

Cited by 143 publications

References 3 publications

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

Variational principles and governing equations in nano-dielectrics with the flexoelectric effect

A study of flexoelectric coupling associated internal electric field and stress in thin film ferroelectrics

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