Unipolar poling-induced high switching speed and improved imprint behaviors for poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin films

Hou, Ying; Lü, Zhaoyue; Pu, Tiansong; Zhang, Yuan; Meng, Xiangjian; Xu, Hongyao

doi:10.1063/1.4858035

Cited by 5 publications

(2 citation statements)

References 20 publications

(25 reference statements)

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“…In this problem, it is important to study the processes of electrical aging (fatigue). Such processes are typical for both inorganic materials 5–18 and organic ferroelectrics 19–26 . The general conclusion following from these papers is that the formation of a space charge in the material plays an important role in the aging process.…”

Section: Introductionmentioning

confidence: 93%

“…Such processes are typical for both inorganic materials [5][6][7][8][9][10][11][12][13][14][15][16][17][18] and organic ferroelectrics. [19][20][21][22][23][24][25][26] The general conclusion following from these papers is that the formation of a space charge in the material plays an important role in the aging process. A feature of polymer ferroelectrics, including the copolymers considered in this study, is that they are characterized by high coercive and breakdown fields.…”

Section: Introductionmentioning

confidence: 99%

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Influence of physical aging of ferroelectric vinylidene fluoride copolymer films on their structural and electrophysical characteristics

Kochervinskiĭ

Gradova

Градов

et al. 2022

J of Applied Polymer Sci

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General problems of structural changes which occur at storage of two‐phase crystalline polymers with a metastable structure at room conditions are considered on the example of a vinylidene fluoride ‐ hexafluoropropylene copolymer. The physical aging occurs in flexible‐chain crystalline polymers (polyethylene, fluoropolymers under consideration, etc.), where, due to low glass transition temperatures, the liquid‐like dynamics of amorphous phase chains is realized at room temperature through cooperative micro‐Brownian motions with short relaxation times. Taking into account that covalent‐bound sections of the chains of the amorphous phase can enter the crystallites, the noted mobility may initiate changes in the size of the latter. Such a possibility is proved by the example of the noted copolymer. At low‐temperature crystallization of a vinylidene fluoride ‐ hexafluoropropylene copolymer from a solution the formed α‐phase crystals have little perfection. The size of the crystals increases when the films are stored in room conditions. Because of the crystal polymorphism, at the same time a certain fraction of γ‐phase crystals which are present in initial films undergo a polymorphic transformation γ → α. These processes lead to an increase in crystallinity. Moreover, during such processes additional structuring is observed, which is reduced to the displacement of various kinds of intra‐chain defects into the amorphous phase (and especially into the surface). Since the copolymers under study are ferroelectrics, they were studied by piezo force microscopy. It was found that despite the crystallization predominantly in nonpolar α‐phase, piezo force microscopy revealed a domain structure, which formation mechanism is discussed. The structural changes at physical aging of the films affect the character of the noted domain structure. Thus, it is suggested that the mechanism of the described structural changes is realized through the developed cooperative mobility of the chains in the amorphous phase, which characterizes the processes of rotational diffusion.

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Section: Introductionmentioning

confidence: 93%