Electrical and optical properties of the TTF-halides

Technical Report · Tue Jun 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7341324· OSTI ID:7341324

Warmack, R. J.; Callcott, T. A.

Recent interest in the highly conductive charge transfer organic crystals, particularly tetrathiofulvalene-tetracyanoquinodimethane (TTF-TCNQ), prompted this investigation of TTF-TCNQ and other systems. Results of conductivity measurements on TTF-TCNQ confirm results obtained by other authors. TTF was found to combine with the halogens to form crystals with interesting electrical properties due to the segregated stacking of the TTF molecules. The monoclinic forms of TTF-I/sub n/ and TTF-Br/sub n/ (n approximately 0.7) have a high conductivity (100-550 (..cap omega..-cm)/sup -1/) which is almost temperature independent for a very broad region near room temperature but displays a thermally activated conductivity at low temperature. Unlike monoclinic TTF-Br/sub n/, monoclinic TTF-I/sub n/ displays a strong hysteresis in its conductivity upon temperature cycling. The conductivity of the orthorhombic form of TTF-I/sub n/ (n = 2) is about five orders of magnitude lower than the monoclinic form at room temperature and is thermally activated over the entire temperature range. Polarized single crystal optical reflectance measurements in the spectral region from 0.6 eV to 5 eV on the two crystalline forms of TTF-I/sub n/ were made. The reflection of light polarized along the conducting axis of the monoclinic crystals was typical of Drude-like free electron gas with the edge occurring at about 1.15 eV. Optical properties were determined by a Lorentzian oscillator fitting procedure. Results indicated that the majority of the visible spectrum can be attritubed to TTF/sup +/ transitions.

• Research Organization: Oak Ridge National Lab., Tenn. (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7341324
• Report Number(s): ORNL/TM-5441
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKENES
BROMIDES
BROMINE COMPOUNDS
CHARGE TRANSPORT
CRYSTAL STRUCTURE
CYCLOALKENES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
IODIDES
IODINE COMPOUNDS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
REFLECTIVITY
SURFACE PROPERTIES