Plasma discharge power dependent AC conductivity of plasma poly(ethylene oxide) thin films

Yakut, Şahin; Deǧer, D.

doi:10.1016/j.tsf.2017.10.048

Cited by 15 publications

(22 citation statements)

References 49 publications

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“…4 a, b, c, d. This behavior may be attributed that the motion of α and β-relaxations can follow the applied electric field at higher frequencies with increasing temperature [25,26]. At second cooling process, the temperatures at which α-relaxation observed shift toward low temperatures with decreasing thickness as shown in Fig.…”

Section: Resultsmentioning

confidence: 79%

“…The mechanism observed at low frequency side and at high temperatures is called as α-relaxation which is attributed to phase transition of structure from rubber state to glassy state. The other mechanism observed at high frequency side and at low temperatures is called as βrelaxation which is attributed to dipolar fluctuation of side chains [20][21][22][23][24][25][26]. It can be detected that the dielectric constants measured at first cooling are greater than the dielectric constants measured at second cooling.…”

Section: Resultsmentioning

confidence: 99%

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Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films

Ulutaş

2018

Cumhuriyet Science Journal

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Dielectric properties of plasma poly (ethylene oxide) (pPEO) thin film samples were investigated at room temperature. The thin film samples with different thicknesses were deposited by plasma assisted physical vapor deposition (PAPVD) technique at 5 W plasma discharge power. The thicknesses were 20, 100, 250, 500 nm. It was observed that dielectric constant increases with increasing thickness. The relaxation times determined by dielectric loss-frequency relation, shift toward higher frequencies with increasing thickness. In addition film thickness, heating processes were defined as another parameter. By this purpose, thin film samples were heated and cooled, respectively. It was observed that maxima and minima of dielectric loss at cooling process take place at lower frequencies in comparison with frequencies at which maxima and minima were detected at heating process. These results may show the effect of dead layer at thinner films. After heating process, it was observed from behavior of dielectric constant and dielectric loss that the crosslinking density increases by heating effect. This effect may cause additional reactions between free radicals which are production of PAPVD. Moreover, dynamic glass transition temperatures were calculated. These temperatures prove the effect of dead layer approximation.

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Section: Resultsmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films

Ulutaş

2018

Cumhuriyet Science Journal

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“…Eş. 7 ile ifade edilir ve bu ifade Jonscher Yasası olarak da adlandırılmaktadır [41]. Bu ifadede σDC frekanstan bağımsız iletkenlik ifadesidir [46].…”

Section: Ac Iletkenliğin Frekansa Ve Sıcaklığa Bağlılığı (Frequency Aunclassified

Polietilen ince filmin dielektrik özelliklerinin frekans, sıcaklığa bağlı davranışı ve camsı geçiş sıcaklığının tespiti

Yakut

2021

Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi

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 Determination of glass transition temperature by VFT model  Higher dielectric constant of PE thin film compared to dielectric constant of bulk PE  Determining glass transition temperature of PE thin film at higher temperatures than glass transition temperature of bulk PE Figure A. The dependence of the frequency value at which the maximum dielectric loss is observed from the dielectric loss obtained from the dielectric loss graph for 35000 g/mol and 750 nm thick polyethylene (PE) thin film (red dots and VFT fit curve) and the temperature dependence of the frequency values at which the maximum electric modulus is observed from the electric modulus graph (blue dots and activation curve) Purpose:The aim of this article is to analyze dielectric properties and glass transition temperature of PE thin film in comparison to bulk PE in order to evaluate the possible application opportunities of PE thin film in enery storage systems. Theory and Methods: PE thin film samples were deposited by thermal evaporation method between Al thin film electrodes under 10-5 Torr vacuum conditions. The dielectric spectroscopy measurements were operated by high frequency empedance analyzer. Results: The results show that thermal evaporation process causes breakage of PE main chain and occurance of oligomers and radicals. These oligomers and radicals may be the reason of increasing dielectric constant as a result of space-charge polarization. Also, the oligomers and radicals may react with each other and the main chain and cause the construction of cross-linked network. The presence of this network is the reason of increasing glass transition temperature. Conclusion: The results obtained for the change of dielectric constant and glass transition temperature show that PE thin films can be thought as candidate for organic energy storage systems.

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“…The polarization of these large chain components are called as α-relaxation [31,32]. This relaxation shifts toward lower frequencies with decreasing temperature.…”

Section: Frequency and Temperature Dependence Of Dielectric Constant mentioning

confidence: 99%

“…It is think that this mechanism appears because of the polarization of free radicals originated from side chains and main chain of PEO and small oligomers. This mechanism is called as β-relaxation [31,32]. β-relaxation can be observed at lower frequencies by decreasing temperature.…”

Section: Frequency and Temperature Dependence Of Dielectric Constant mentioning

confidence: 99%

The thickness dependence of dielectric properties in the plasma polymer thin films

Ulutaş

2018

Can. J. Phys.

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In this study, the results of dielectric spectroscopy of plasma polymerized poly(ethylene oxide) thin films are presented. The films were deposited by plasma-assisted physical vapour deposition at radio-frequency plasma discharge power of 5 W, and film thicknesses of 20, 100, and 250 nm. Dielectric measurements of the films were performed in the frequency range of 10−1–107 Hz and temperature was scanned between 173 and 353 K. The dielectric constant ([Formula: see text]) and dielectric loss ([Formula: see text]) of plasma polymerized poly(ethylene oxide) thin films were calculated by measuring capacitance (C) and dielectric loss factor (tanδ). It was observed that there were two relaxation mechanisms in the investigated frequency range. These were called α and β relaxations. These relaxations shift toward higher frequencies with increasing temperature. Moreover, α-relaxation starts to appear at different temperatures. This shows the difference between the polarizability abilities of samples at the same temperature and same frequencies. The reason for this behavior can be expressed by the dead layer concept, which is a result of good adhesion of the bottom layer of plasma polymer to the substrate. In light of these interpretations, with thinner samples it is possible to have structurally similar thin films like thin films deposited at high plasma power. A thinner film may support more transparency and these thinner films may be effective as coverage of optical devices, such as lenses, visors, etc.

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Plasma discharge power dependent AC conductivity of plasma poly(ethylene oxide) thin films

Cited by 15 publications

References 49 publications

Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films

Thickness Dependent Dielectric Loss of Plasma Poly (Ethylene Oxide) Films

Polietilen ince filmin dielektrik özelliklerinin frekans, sıcaklığa bağlı davranışı ve camsı geçiş sıcaklığının tespiti

The thickness dependence of dielectric properties in the plasma polymer thin films

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