BEDT-TTF-based synmetal: Synthesis, structure, ESR, and electrical properties of (BEDT-TFF)Hg sub 0. 776 (SCN) sub 2

Journal Article · · Chemistry of Materials; (United States)

OSTI ID:7038939

Wang, H H; Beno, M A; Carlson, K D; Thorup, N; Murray, A; Porter, L C; Williams, J M ^[1]; Maly, K; Bu, Xianhui; Petricek, V; Cisarova, I; Coppens, P ^[2]; Jung, D; Whangbo, M H ^[3]; Schirber, J E; Overmyer, D L ^[4]

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1. Argonne National Lab., IL (United States)
2. State Univ. of New York, Buffalo (United States)
3. North Carolina State Univ., Raleigh (United States)
4. Sandia National Lab., Albuquerque, NM (United States)

A new charge-transfer salt, (BEDT-TFF)Hg{sub 0.776}(SCN){sub 2} (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene), has been synthesized and found to exhibit metallic conductivity to 13 K. This new synmetal has a composite columnar stack structure in which the BEDT-TTF donor molecule and SCN{sup {minus}} ligands form one subsystem with a triclinic cell. The two sublattices share the b-axis direction, which is the direction of molecular stacking, but the periodicity in this direction differs for the two sublattices. Since the SCN{sup {minus}} ligands and the Hg atoms occur in different subsystems, the Hg coordination varies from unit cell to unit cell. The interaction between the two sublattices gives rise to each being modulated. The modulation has been analyzed by use of the intensities of the satellite reflections. Four-probe resistivity and single-crystal ESR measurements show that (BEDT-TFF)Hg{sub 0.776}(SCN){sub 2} is metallic down to at least 13 K. Radio-frequency penetration depth studies at ambient pressure indicate that superconductivity is not observed down to 0.6 K. Tight-binding band electronic structure calculations on the average structure' of the BEDT-TTF stacks show this material to be strictly one-dimensional. The conflict between this theoretical result and conductivity measurements appears to be resolved by use of a commensurate approximation to the modulation of the BEDT-TTF lattice in the band structure calculations. The Fermi surfaces based on the commensurate approximation are all closed; therefore, (BEDT-TFF)Hg{sub 0.776}(SCN){sub 2} is expected to be a two-dimensional metal.

• DOE Contract Number: W-31109-ENG-38; FG05-86ER45259
• OSTI ID: 7038939
• Journal Information: Chemistry of Materials; (United States), Journal Name: Chemistry of Materials; (United States) Vol. 3:3; ISSN CMATE; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360606 -- Other Materials-- Physical Properties-- (1992-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
BAND THEORY
BEDT-TTF
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON SPIN RESONANCE
ENERGY LEVELS
EXPERIMENTAL DATA
FERMI LEVEL
HETEROCYCLIC COMPOUNDS
INFORMATION
ISOTHIOCYANATES
LATTICE PARAMETERS
MAGNETIC RESONANCE
MERCURY COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANIC SUPERCONDUCTORS
PHYSICAL PROPERTIES
RESONANCE
STOICHIOMETRY
SUPERCONDUCTORS
SYNTHESIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K