کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10618702 | 988178 | 2005 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Thermal degradation of the dielectric relaxation of 10-90% (w/w) zeolite-conducting polypyrrole composites
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
بیومتریال
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Thermal degradation of the dielectric relaxation of 10-90% (w/w) zeolite-conducting polypyrrole composites Thermal degradation of the dielectric relaxation of 10-90% (w/w) zeolite-conducting polypyrrole composites](/preview/png/10618702.png)
چکیده انگلیسی
The effect of thermal aging of 10-90Â wt% zeolite-conducting polypyrrole composite on its dielectric properties is studied in the frequency range 10â2 to 2Â ÃÂ 106Â Hz from room temperature to liquid nitrogen temperature. A dielectric relaxation mechanism, which appears in the fresh samples, is influenced by the thermal annealing. The frequency fmax where a maximum of a dielectric loss peak is located decays exponentially with the aging time and the intensity of the loss peaks shows a maximum at intermediate aging time. A modified Williams-Landel-Ferry law describes the temperature variation of fmax in all specimens. Increasing activation energy values on increasing the aging duration are obtained. The temperature dependence of fmax and the activation energy (regarded as the height of a potential barrier) are different from those characterizing the macroscopic conductivity, which is described by the charging energy limited tunneling model. The intensity of the dielectric mechanism in thermally treated samples deviates from the linear decrease with inverse temperature occurring in fresh polypyrrole. Although the thermal degradation of the logarithm of the dc conductivity decays proportional with the root of the aging time, the equivalent conductivity obtained from the dielectric data decays exponentially with aging duration. Time constants are obtained in both cases. The model of Barton-Nakajima-Namikawa (BNN) can hardly interconnect the dc conductivity with the relaxation process in fresh sample. The divergence augments with the aging time. The thermal aging law and the inadequacy of the BNN model probably indicates that the dc process is probably irrelevant to the relaxation process.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Synthetic Metals - Volume 150, Issue 2, 30 April 2005, Pages 145-151
Journal: Synthetic Metals - Volume 150, Issue 2, 30 April 2005, Pages 145-151
نویسندگان
A.N. Papathanassiou, J. Grammatikakis, I. Sakellis, S. Sakkopoulos, E. Vitoratos, E. Dalas,