Low frequency dielectric relaxation phenomena in conducting polypyrrole and conducting polypyrrole-zeolite composites
| Autor: | S. Sakkopoulos, I. Sakellis, J. Grammatikakis, Evangelos Vitoratos, Anthony N. Papathanassiou, Evangelos Dalas |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 96:3883-3888 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.1788846 |
| Popis: | The dielectric properties of polypyrrole-zeolite composites up to 50%w∕w zeolite are studied in the frequency range from 10−2to2×106Hz from room temperature to liquid nitrogen temperature. The complex permittivity formalism reveals a temperature dependent relaxation in all samples except for the 25%w∕w zeolite composite. The frequency fmax where a maximum of a loss peak is located varies with temperature by the Williams-Lander-Ferry law. The values of the activation energy of the relaxation process (which are of the order of polaronic dc conductivity) have the tendency to reach a minimum in the 25%w∕w composition, which is a loss-free composite. The 50%w∕w zeolite behaves as a dielectric where ionic relaxation dominates. The temperature variation of the strength of the dielectric mechanism follows a Curie law, apart from 50%w∕w zeolite where the dielectric strength is practically constant. The frequencies, where loss peaks are maximum, as well as dc conductivity follow qualitatively the same temperature l... |
| Databáze: | OpenAIRE |
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