Polar topological structures in ferroelectric materials

Tan, Congbing; Zhong, Xiangli; Wang, Jinbin

doi:10.7498/aps.69.20200311

Cited by 7 publications

(2 citation statements)

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“…[ 34 ] Theoretical physicists employed the first principles to predict that the strong depolarization field generated by low‐dimensional ferroelectric nanoparticles can stabilize the topological structure at the nanoscale. [ 35 ] To achieve a short‐range local structure to form a topological configuration, a strong local depolarization field that is counter to the long‐range ferroelectricity can be formed by introducing external strain. The required strain is derived from the local symmetry breaking caused by some other SFUs such as interfaces, nanodots, and localized composition heterogeneity, and so forth.…”

Section: Main Bodymentioning

confidence: 99%

Structural‐functional unit ordering for high‐performance electron‐correlated materials

Peng

et al. 2023

Interdisciplinary Materials

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Electron‐correlated materials have been drawing ever‐increasing attention due to their fascinating physical behaviors and extensive application scenarios. In this review, a new method for material research and design (R&D), named structural‐functional unit ordering (SFU ordering), which is presented, overcomes the shortcomings—for example, the limitation of finite chemical elements and long R&D circle‐of conventional strategy and thus provides guidance for the design of these high‐performance functional materials on demand. Meanwhile, with the development of material characterization technologies, SFUs of different scales and types can be directly observed, which, moreover, regulate the corresponding orderings. The review, starts with an introduction of the profile for SFU ordering and the synergistic effect between SFUs. Then, studies on several new high‐performance electronic‐correlated materials, for example, a ferromagnetic semiconductor with local spin, ferromagnetic metals with spin topologies, ferroelectric thin films with polar topologies, piezoelectric thin films with nanopillars enclosed by charged boundaries, thermoelectric materials with local ferromagnetic nanoparticles and topotactic phase transformation with conducting nanofilaments are stated in detail one by one. The vital aspect is the breaking of local symmetry, the construction, the structure, of SFUs and their orderings existing or theoretically existing, together with the enhanced/new performance. All in all, the main comments of the review tend to the remaining challenges, promising design approaches for the SFUs, and their orderings for high‐performance functional materials.

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Section: Main Bodymentioning

confidence: 99%

Structural‐functional unit ordering for high‐performance electron‐correlated materials

Peng

et al. 2023

Interdisciplinary Materials

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“…[7,8,9] Scientists are now trying to more accurately visualize these concentric rings to tune and to optimize piezoelectric device performance. [10,11] Another way to maximize output from these piezoelectric polymers is to optimize the device design. [12,13] An example is in the design of piezoelectric microphones.…”

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confidence: 99%

PVDF Based Static Charge Induced Flexoelectric Microphone

Shehzad

Pan

Wang

et al. 2023

Adv Elect Materials

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However, to effectively tune ferroelectric polymer materials and devices, a complete understanding of the polarization phenomena is critical. [6] The discovery of polarization whirlpools in strained ferroelectric polymers has opened up new vistas of research. [7,8,9] Scientists are now trying to more accurately visualize these concentric rings to tune and to optimize piezoelectric device performance. [10,11] Another way to maximize output from these piezoelectric polymers is to optimize the device design. [12,13] An example is in the design of piezoelectric microphones. Thin film piezoelectric microphones are posing great limitations if we use it in sophisticated devices. [14] Piezoelectric microphones require high sound throughput and generate relatively small output signals. [15] These output signals can be enhanced by tuning the piezoelectric properties. [16] FE behavior of dielectric materials was discovered in 1950. Initially, the weak FE behavior of dielectrics was reported. However, the enhanced response of FE behavior was reported in early 2000 for Pervoskite ceramics. [17] Initial measurement of the FE coefficient in ceramics was difficult and empirical values were three to eight orders of magnitude higher than theoretically predicted values. [18] The FE coefficient in perovskite ceramics, µ, was proportional to the dielectric susceptibility χ and can be written as µ = χ × e/a-, [19] where e is the electron charge and a is the unit cell dimension. [20] The empirically measured FE response not only depends on intrinsic material ferroelectricity but is also affected by extrinsic forces such as strain gradient that may also affect results. [21] In attempting to optimize device design, researchers found that the strain gradient in pervoskite ceramics can be increased by reducing size. [22] Therefore the equation (µ = χ × e/a) can be further expressed more generally as: [23] Polyvinylidenedifluoride (PVDF)-based microphones are either categorized as piezoelectric (PE) microphones or flexoelectric (FE)-induced PE microphones. Based on the production of electrostatic charge and higher sensitivity, here, a static charge induced flexoelectric microphone (SC I F E M) is introduced. In this research, two SC I F E M transducers are fabricated, one by sandwiching P(VDF-TrFE) laminate between pair of two aluminum electrodes wrapped in stretched paper sheets (called Device 1) and the other by sandwiching P(VDF-TrFE) laminate between a pair of two Al electrodes wrapped in stretched rubber sheets (called Device 2). Devices 1 and 2 are compared with a simple PVDF-based FE microphone (called Device 0). In this study, Devices 0, 1, and 2 are characterized for flexoelectric (FE) and charge induction (CI) properties.It is observed that despite its poor FE behavior, higher sensitivity of Device 1 is due to its electrostatic charge induced beta phase present at 1170 cm −1 of Fourier transform infrared spectra. The X-Ray diffraction spectroscopy is also performed in accordance to the polar beta phase. It is reported that due to ...

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