Organic and polymeric superconductors. Final report, 30 September 1992-29 March 1996
The synthetic chemistry of dithiadiazafulvalenes (DTDAF) was studied in detail: these one and two-electron donors, more powerful than the well-known tetrathiafulvalenes (TTF, 1), but more chemically more tractable than the unstable tetraazafulvalenes, are a significant departure from ordinary organic donors, and therefore show promise in the search for new organic superconductors. A 2:5 complex of diphenyldiacetyldit hiadiazafulvalene (o2Ac2DTDAF, 4c) with the electron acceptor tetracyanoquinodimethan (TCNQ, 11a), including one molecule of acetonitrile, the solvent of crystallization (CH3CN), provided room-temperature conductivity o=0.011 S/cm (Siemens per centimeter). An unusual diamagnetic flux exclusion signal (for 5 per cent of the sample at 4.4 Kelvin) was determined to be an artifact due to a ferromagnetic impurity. A TCNQ complex of dimethyltetracety1DTDAF, 4b had o=0.083 S/cm at room temperature. A new acceptor, dioxotetracyanobisindanedione vinylidene (DOTCBIV), 5, provided a complex with TTF with o=0.6 S/cm at room temperature. Many complexes with fullerene, C60 (12), were made, but were electrically insulating. Studies of Langmuir-Blodgett films of potassium-doped C60 (monolayers on polyethylene terephthalate) may help to determine the boundary between 2-D and 3-D superconductivity.
- Research Organization:
- Alabama Univ., University, AL (United States). Dept. of Chemistry
- OSTI ID:
- 484700
- Report Number(s):
- AD-A-322702/2/XAB; CNN: Contract F49620-92-J-0529; TRN: 71470339
- Resource Relation:
- Other Information: PBD: 12 Feb 1997
- Country of Publication:
- United States
- Language:
- English
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