Accelerated and decelerated polarization reversal in thin vinylidene fluoride/trifluoroethylene copolymer films
Accelerated and decelerated polarization reversal in thin vinylidene fluoride/trifluoroethylene copolymer films
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DOI：
10.1109/tdei.2010.5539676
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发表时间：
2010-08
影响因子：
3.1
通讯作者：
Y. Arayashiki;T. Nakajima;Y. Takahashi;T. Furukawa
中科院分区：
文献类型：
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作者：
Y. Arayashiki;T. Nakajima;Y. Takahashi;T. Furukawa
利用一系列双极开关电场脉冲研究了偏氟乙烯/三氟乙烯共聚物薄膜在连续极化反转过程中的铁电开关特性。结果表明，偏振反转随脉宽Δt的减小而加速，随Δt的增大而减慢。对于给定的Δt，开关时间ts取决于脉冲高度E，符合指数规律ts∞EEA/E，即当Δt从10μS增加到10 000 GV/m时，Ea从0.5GV/m增加到1.2GV/m，而Ts∞在8 ns时保持不变。这些结果是根据ts对先前极化历史的依赖来解释的，该极化历史产生包含各种缺陷和无序的不同的偏振态，这些缺陷和无序在随后的转换过程中影响成核几率和生长速度。在短/增量/t处的特殊加速归因于有助于产生反转磁区的临界核的非开关极化。在Long/Delta/t处的显著减速归因于在OFF期间观察到的缓慢介电松弛的结构稳定。分别讨论了铁电加热和空间电荷重分布对加速和减速的影响。
Ferroelectric switching characteristics during continuous polarization reversal were investigated in thin vinylidene fluoride/trifluoroethylene copolymer films by using a train of bipolar on-off electric field pulses. It was found that polarization reversal is accelerated as the pulse width Δt is decreased whereas it is decelerated as Δt is increased. For a given Δt, the switching time ts depends on the pulse height E in accordance with an exponential law ts∞eEa/E in that Ea increases from 0.5 GV/m to 1.2 GV/m as Δt is increased from 10 μs to 1000 s whereas ts∞ remains constant at 8 ns. These results are interpreted in terms of the dependence of ts on previous poling history that produces diverse polarization states containing various defects and disorder that affect the nucleation probability and growth velocity in the following switching process. Particular acceleration at short /Delta/t was attributed to unswitched polarization that aids in the generation of critical nuclei of reversed domains. Marked deceleration at long /Delta/t was attributed to structural stabilization observed as slow dielectric relaxation during the off period. The effects of ferroelectric heating and space charge redistribution are discussed in relation to acceleration and deceleration, respectively.