<i>Ab Initio</i>Studies of Polarization and Piezoelectricity in Vinylidene Fluoride and BN-Based Polymers

Nakhmanson, Serge; Nardelli, Marco Buongiorno; Bernholc, J.

doi:10.1103/physrevlett.92.115504

Cited by 122 publications

(107 citation statements)

References 33 publications

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“…As can be seen from Table I, the various models do not agree with each other, which recently motivated us to apply modern ab initio techniques to compute spontaneous polarization in ␤-PVDF. 16 Our results ͑P 3 sp = 0.178 C / m 2 ͒ clearly show that the majority of the previous models, fitted either to experiment or to a simple sum of the bond-dipole moments in an individual VDF monomer 4,7 ͑Ӎ2 D͒, underestimate the strength of the dipole-dipole interaction in this material. The polarization obtained in Ref.…”

Section: Introductionsupporting

confidence: 51%

Collective polarization effects inβ-polyvinylidene fluoride and its copolymers with tri- and tetrafluoroethylene

2005

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The polar properties of the ␤ phase of polyvinylidene fluoride ͑PVDF͒ and its copolymers with tri-and tetrafluoroethylene are investigated theoretically at different VDF-to-copolymer ratios. The calculations show that polarization in such polymers is described by cooperative, quantum-mechanical interactions between polymer chains, which cannot be viewed as a superposition of rigid dipoles. For ␤-PVDF, the monomer dipole moment is increased by 50% ͑from 2 to 3 D͒ as the isolated chains are brought together to form a crystal. In PVDF crystals containing copolymers, we observe a weakly parabolic dependence of monomer dipole moments on copolymer concentration.

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Section: Introductionsupporting

confidence: 51%

Collective polarization effects inβ-polyvinylidene fluoride and its copolymers with tri- and tetrafluoroethylene

2005

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“…In order to compare present values of the direct piezoelectric response of the monolayers with those of standard 3D piezoelectric materials, we need to define a volume and to consider, as it is generally done in these cases, a graphite-like system with interlayer distance 67 of 3.35 Å. It follows that BNG structures exhibit a direct macroscopic piezoelectricity that is about 10 times larger than that of pure α-quartz 65 or Ge-doped α-quartz, 44 5 times larger than that (0.27 C/m 2 ) of polyvinylidene fluoride and its copolymers 68 and comparable to that of bulk GaN and AlN. 66 In order to confirm that the same finite, large, piezoelectric response can be induced in graphene simply by breaking its inversion symmetry center with any in-plane defect, in the limit of low defect concentration, we introduce two other defects: holes which reduce the symmetry of graphene from D 6h to D 3h and C 2v , respectively.…”

Section: Resultsmentioning

confidence: 99%

Inducing a Finite In-Plane Piezoelectricity in Graphene with Low Concentration of Inversion Symmetry-Breaking Defects

et al. 2015

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We show that a finite in-plane piezoelectricity can be induced in graphene by breaking its inversion center with any in-plane defect, in the limit of vanishing defect concentration. We first consider different patterns of BN-doped graphene sheets of D 3h symmetry, whose electronic and piezoelectric (dominated by the electronic rather than nuclear term) properties are characterized at the ab initio level of theory. We then consider other in-plane defects, such as holes of D 3h or C 2v point-symmetry, and confirm that a common limit value (for low defect concentration) of the piezoelectric response of graphene is obtained regardless of the particular chemical or physical nature of the defects (e 11 ≈ 4.5 × 10 −10 C/m and d 11 ≈ 1.5 pm/V for direct and * To whom correspondence should be addressed † Equipe de Chimie Physique, IPREM UMR5254, Université de Pau et des Pays de l'Adour, 64000 Pau, France ‡ Chemistry Department, Faculty of Science, Minia University, Minia 61519, Egypt ¶ Dipartimento di Chimica and Centre of Excellence NIS (Nanostructured Interfaces and Surfaces), Università di Torino, via Giuria 5, IT-10125 Torino (Italy) 1 converse piezoelectricity, respectively). This in-plane piezoelectric response of graphene is one-order of magnitude larger than the out-of-plane previously investigated one.

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“…The LGD intrinsic coercive field EC was found experimentally in copolymer thin films at the nanoscale [31]. Further experiments indicated that bulk polymeric ferroelectric films behave in accordance with KAI switching mechanism, while the nanoscale films reveal homogeneous LGD switching [12,13,27].…”

Section: Intrinsic Homogeneous Polarization Switchingmentioning

confidence: 72%

“…Now these LB polymer films are widely explored experimentally, using various techniques, including nanoscale characterization by atomic force microscopy (AFM) and piezoresponse force microscopy (PFM) method [4][5][6][7][8][9][10][11], and theoretically, using various computational methods [12][13][14][15][16][17][18][19][20][21]. These novel ferroelectric nano-materials are very promising for nanobiotechnology, nanobiomedicine, bio-and microelectronics, and as a prospective component of various nanocomposites and "intellectual" templates with "smart surface" properties.…”

Section: Introductionmentioning

confidence: 99%

Анализ Вычислительных И Экспериментальных Исследований Переключения Поляризации В ПВДФ И П (Вдф-ТрФЭ) Сегнетоэлектрических Пленках На Наноуровне

Bystrov¹

2015

Math.Biol.Bioinf.

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Abstract. In this paper, molecular models are used to investigate and analyze the polarization switching in the polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) Langmuir-Blodgett (LB) nanofilms, in comparison with the experimental data at the nanoscale. Quantum-mechanical calculations and modeling, as well as molecular dynamics (MD) simulations based on semi-empirical quantum-chemical methods (such as PM3), show that the energy of the studied PVDF and P (VDF-TrFE) molecular structures, and their polarization switching proceed by the intrinsic homogeneous switching mechanism in the framework of the phenomenological theory of Landau-Ginzburg-Devonshire (LGD) in the linear approximation at low values of the electric field. The magnitude of the resulting critical coercive field is within the EC ~ 0.5 ... 2.5 GV/m, which is consistent with experimental data. It is also found that the uniform polarization switching mechanism of the polymer chains PVDF and P (VDF-TrFE) is due to the quantum properties of the molecular orbitals of the electron subsystem. This is clearly seen in both the polarization hysteresis loops, and the total energy changes. In this case, the turnover chain time, obtained by molecular dynamics within semi-empirical quantum-chemical PM3 approach in a limited Hartree-Fock approximation, when approaching this critical point, increases sharply, tending to infinity, which corresponds to the theory of LGD. Otherwise, at the high values of the applied electric field the polarization switching correspond to the extrinsic domain mechanism in the frame of the microscopic KolmogorovAvrami-Ishibashi (KAI) theory, describing bulk ferroelectric crystals and thick films. The performed analysis of computational and experimental data allows us to estimate the critical sizes of the possible transition region approximately on the order of 10 nm between intrinsic homogeneous and extrinsic domain switching mechanisms.

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Ab InitioStudies of Polarization and Piezoelectricity in Vinylidene Fluoride and BN-Based Polymers

Cited by 122 publications

References 33 publications

Collective polarization effects inβ-polyvinylidene fluoride and its copolymers with tri- and tetrafluoroethylene

Collective polarization effects inβ-polyvinylidene fluoride and its copolymers with tri- and tetrafluoroethylene

Inducing a Finite In-Plane Piezoelectricity in Graphene with Low Concentration of Inversion Symmetry-Breaking Defects

Анализ Вычислительных И Экспериментальных Исследований Переключения Поляризации В ПВДФ И П (Вдф-ТрФЭ) Сегнетоэлектрических Пленках На Наноуровне

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