Principal Electrical Conductivities in the Organic Conductors TEA.(TCNQ)2 and TTF.TCNQ: The Microwave Approach |
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| Authors: | Jean Louis Miane Alain Filhol Manuel Almeida Ib Johannsen |
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| Institution: | 1. Laboratoire de Physique Expérimentale, Université de Bordeaux I , 33405, Talence, France;2. Institut Laue , Langevin, 156X, 38042, Grenoble, Cedex, France;3. Chemistry Department , LNETI , P-2686, Sacavém Codex, Portugal;4. Department of General and Organic Chemistry , University of Copenhagen , DK-2100, Copenhagen, Denmark |
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| Abstract: | Abstract We describe a microwave technique to measure the directions and magnitude of the principal electrical conductivities and permittivities of organic conductors. The method is applied to single crystals of triethylammonium-bis 7,7,8,8-tetracyano-p-quinodimethane (TEA.(TCNQ)2) and of tetrathiafulvalenium-7,7,8,8-tetracyano-p-quinodimethane (TTF.TCNQ). For the former, the apriori set of principal axes (a*, (a*∧c), c) is confirmed with principal conductivities of 430, 5.3 and 0.41–0.77 Ω?1m?1 respectively. The room temperature permittivities have been measured for the first time (ε*α ～ 5.4–5.5, ε*α∧c ～ 7.5). For the latter it is clearly shown that the principal electrical axes are (a, b, c*) and, in contrary to earlier d.c data, we observe σc· < σ<a which is more consistent with the anisotropy of interchain interactions in this compound. The observed transverse and longitudinal anisotropies (～3.3 102 and 2.8 104 respectively) are larger than believed up to now. |
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| Keywords: | microwave electrical conductivity permittivity anisotropy organic conductors TEA (TCNQ)2 TTF TCNQ |
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