Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

This review attempts to present the most salient developments of research on organic conductors and superconductors during the past 10 years. A theoretical introduction treats instabilities of quasi-one-dimensional electron systems and associated precursor effects which are relevant to the experimental results on organic conductors. We then describe the characterization of quasi-one-dimensional organic conductors by their transport, optical and magnetic properties. Finally, two sections are devoted to the experimental investigation of the low temperature instabilities: lattice instability in TTF-TCNQ and related compounds, superconducting or antiferromagnetic instabilities in the (TMTSF) 2 X series. The importance of one-dimensional fluctuations is emphasized in both lattice and superconducting instabilities.

Organic conductors and superconductors

Investigation of the magnetic and transport properties of single-walled small-diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 kelvin, 4 angstrom tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 kelvin. Statistical mechanic calculations based on the Ginzburg-Landau free-energy functional yield predictions that are in excellent agreement with the experiments.

https://science.sciencemag.org/content/sci/292/5526/2462.full.pdf

Superconductivity in 4 angstrom single-walled carbon nanotubes.

Superconductivity, that is, the possibility for electrons to flow through a conductor without any energy loss, has been the fuel for a very large number of industrial applications of physics in the twentieth century. Just to mention some of them which are important in current life, we have the power loss energy transfer, the production of very strong magnetic fields for medical imaging or for plasma confinement (the fusion problem) voltage standards, particle accelerators, and magnetic flux sensors.

Organic conductors: from charge density wave TTF-TCNQ to superconducting (TMTSF)2PF6.

Fullerene polymers: synthesis and properties.

It is shown that C60 single crystals can be polymerized under relatively modest pressure-temperature conditions. The resulting single crystals exhibit long-range order and they are made up of 12 orientation variants. The structure is orthorhombic with a short intermolecular distance along the chains (9.14 A), characteristic of covalent bonding. We propose a structural mechanism for the polymerization of fullerene-based compounds; it involves a shift of one of the (111) cubic planes together with a shortening of the (111) spacing. The configuration of the polymer chains presents interesting relations with that found in the A1C60 polymer compounds.

https://iopscience.iop.org/article/10.1209/epl/i1997-00424-4/pdf

First X-ray diffraction analysis of pressure polymerized C60 single crystals

X-Ray Scattering Evidence for Anion Ordering and Structural Distortions in the Low-Temperature Phase of Di(Tetramethyltetraselanafulva1enium) Perrhenate i (TMTSF),ReO,I

/pdf/x-ray-diffuse-scattering-study-of-superstructure-formation-3ttdy6jkyi.pdf

X-ray diffuse scattering study of superstructure formation in tetramethyltetraselenafulvalenium perrhenate (TMTSF)2ReO4 and nitrate (TMTSF) 2NO3

The high symmetry and round shape of the fullerene molecules induce orientational phenomena that play an important role in the properties of the fullerene compounds. This is illustrated in this review which is focused on the orientational properties of C60 monomer and polymer structures. First, the orientational state of C60 at room temperature, its peculiar orientational ordering phase transition and the associated glassy state are described, together with the corresponding temperature-pressure phase diagram. Then, a summary of the polymerization processes and of the varied structures obtained under high-pressure high-temperature conditions or via doping by alkali metals is proposed. Finally, some information is given on the orientational properties of C60 layers and surfaces.

Structures, phase transitions and orientational properties of the C60 monomer and polymers.

The high symmetry and round shape of the fullerene molecules induce orientational phenomena that play an important role in the properties of the fullerene compounds. This is illustrated in this review which is focused on the orientational properties of C 6 0 monomer and polymer structures. First, the orientational state of C 6 0 at room temperature, its peculiar orientational ordering phase transition and the associated glassy state are described, together with the corresponding temperature-pressure phase diagram. Then, a summary of the polymerization processes and of the varied structures obtained under high-pressure high-temperature conditions or via doping by alkali metals is proposed. Finally, some information is given on the orientational properties of C 6 0 layers and surfaces.

Roger Moret

Papers

First X-ray diffraction analysis of pressure polymerized C60 single crystals

X-Ray Scattering Evidence for Anion Ordering and Structural Distortions in the Low-Temperature Phase of Di(Tetramethyltetraselanafulva1enium) Perrhenate i (TMTSF),ReO,I

X-ray diffuse scattering study of superstructure formation in tetramethyltetraselenafulvalenium perrhenate (TMTSF)2ReO4 and nitrate (TMTSF) 2NO3

Structures, phase transitions and orientational properties of the C60 monomer and polymers.

Structures, phase transitions and orientational properties of the C60 monomer and polymers