An effect of the electrode material on space charge relaxation in ferroelectric copolymers of vinylidene fluoride
An effect of the electrode material on space charge relaxation in ferroelectric copolymers of vinylidene fluoride
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DOI：
10.1063/1.4938016
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发表时间：
2015-12-28
影响因子：
3.2
通讯作者：
Lebedinskii, Yuri
中科院分区：
文献类型：
--
作者：
Kochervinskii, Valentin;Malyshkina, Inna;Lebedinskii, Yuri
研究了杂质载体在组成为71/29和94/6的偏氟乙烯和四氟乙烯共聚物各向同性薄膜中形成空间电荷的弛豫过程。采用真空蒸发法制备了铝和金对称电极。在温度高于100℃的Al电极的情况下，观察到巨大的低频介电色散，而在Au电极的薄膜中则没有。用x射线光电子能谱法研究了这一现象的原因。结果表明，在Al沉积过程中，形成了共聚物膜表面不具有的Al- c、Al- f和Al2O3等新的官能团。它们被认为是杂质载体的陷阱，因此电极被部分堵塞。这导致在金属-聚合物边界上出现巨大的电极极化，而在金电极的情况下没有发生这种情况。分析了链上不同氟原子含量共聚物的Au4f线参数。这些原子数量的增加会导致谱线向高能量方向移动。这种现象与电子密度从Au原子向对电子有高亲和力的F原子转移的增加有关。(C) 2015 AIP出版有限责任公司
Processes of relaxation of space charges formed by impurities carriers in isotropic films of vinylidene fluoride and tetrafluoroethylene copolymers of the composition 71/29 and 94/6 were studied. Al and Au symmetric electrodes deposited by evaporation in vacuum have been used. In the case of Al electrodes at temperatures above 100 degrees C, giant low frequency dielectric dispersion was observed, while it is absent in films with Au electrodes. Causes of this phenomenon were studied by the X-ray photoelectron spectroscopy. It was shown that at Al deposition, new functional groups, such as Al-C, Al-F, and Al2O3, which are not characteristic of the copolymer film surface, formed. They were supposed to be traps for impurity carriers and because of this the electrode became partially blocked. This led to appearance of the giant electrode polarization on the metal-polymer boundary, which did not take place in the case of Au electrodes. Parameters of the Au4f line for the copolymer with different contents of fluorine atoms in the chain were analyzed. An increase in the number of these atoms was shown to result in the line shift to higher energies. This phenomenon was associated with an increase in the shift of the electron density from Au atoms to the F ones which has a high affinity to electrons. (C) 2015 AIP Publishing LLC.