Similarities and differences in the structural and electronic properties of. kappa. -phase organic conducting and superconducting salts

Journal Article · Wed Dec 13 00:00:00 EST 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00324a018· OSTI ID:7121902

Jung, D; Evain, M; Novoa, J J; Whangbo, M H ^[1]; Beno, M A; Kini, A M; Schultz, A J; Williams, J M ^[2]; Nigrey, P J ^[3]

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1. North Carolina State Univ., Raleigh (USA)
2. Argonne National Lab., IL (USA)
3. Sandia National Labs., Albuquerque, NM (USA)

The similarities and differences in the crystal and band electronic structures of four {kappa}-phase tetrathiafulvalene-based organic conducting salts {kappa}-(BEDT-TTF){sub 2}X (X{sup {minus}} = Cu(NCS){sub 2}{sup {minus}}, I{sub 3}{sup {minus}}), {kappa}-(MDT-TTF){sub 2}AuI{sub 2}, and {kappa}-(BMDT-TTF){sub 2}AU(CN){sub 2} have been examined. Donor dimers have a bond-over-ring arrangement in the superconducting salts {kappa}-(BEDT-TTF){sub 2}X (X{sup {minus}} = Cu(NCS){sub 2}{sup {minus}}, I{sub 3}{sup {minus}}) and {kappa}-(MDT-TTF){sub 2}AuI{sub 2} but a bond-over-bond arrangement in the nonsuperconducting salt {kappa}-(BEDT-TTF){sub 2}Au(CN){sub 2}, so that the intradimer spacing is considerably larger in the nonsuperconducting than in the superconducting {kappa}-phases. The terminal ethylene groups of BEDT-TTF have a staggered arrangement in the high-T{sub c} salts {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} (T{sub c} = 10.4 K) and {beta}*-(BEDT-TTF){sub 2}I{sub 3} (T{sub c} = {approximately} 8 K) but are eclipsed in the low-T{sub c} salts {kappa}(BEDT-TTF){sub 2}I{sub 3} (T{sub c} = 3.6 K), {beta}-(BEDT-TTF){sub 2}AuI{sub 2} (T{sub c} = 5.0 K), and {beta}-(BEDT-TTF){sub 2}IBr{sub 2} (T{sub c} = 2.8 K). All the Fermi surfaces of the {kappa}-phase can be described in terms of overlapping distorted circles and hence are essentially two-dimensional in nature. However, the Fermi surface of the nonsuperconducting {kappa}-phase, {kappa}-(BMDT-TTF){sub 2}Au(CN){sub 2} exhibits a partial nesting in contrast to the case of the superconducting {kappa}-phases, which is probably responsible for the metal-insulator transition at {approximately} 60 K. 26 refs., 8 figs., 2 tabs.

• DOE Contract Number: FG05-86ER45259
• OSTI ID: 7121902
• Journal Information: Inorganic Chemistry; (USA), Vol. 28:25; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
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PHYSICAL AND ANALYTICAL CHEMISTRY
COPPER COMPLEXES
MOLECULAR STRUCTURE
CYANIDES
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THIOCYANATES
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
SUPERCONDUCTIVITY
ANTITHYROID DRUGS
CARBONIC ACID DERIVATIVES
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ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HORMONE ANTAGONISTS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
TRANSITION ELEMENT COMPLEXES
360603* - Materials- Properties
400201 - Chemical & Physicochemical Properties