Fullerene Superconductivity

Keywords Fullerenes Superconductivity Antiferromagnetism Metal-insulator transition Electron correlation Intermediate valence... 

S. Margadonna K. Prassides (2002). J. Solid State Chem., 168, 639-652. Recent advances in fullerene superconductivity. 

The discoveries of conductivity and superconductivity in K3C60 and Rb3Cgo were great events in science during the 1990s. This happened within five years after the discovery of high Tc superconductivity and the discovery of fullerenes. Superconductivity was later discovered in a number of other A3C60 compounds, where A stand for any of the alkali atoms Li, Na, K, Rb, or Cs, but never in any of the numerous alkali fullerenes with a different number of carbon atoms than 60. 

It is noted that, as previously mentioned, there is a rapidly growing interest in the superconductivity of inorganic fullerene compounds. 

Interestingly, if the C50 fullerene doped by alkali metals is rapidly cooled down to the liquid nitrogen temperature, polymerization does not occur. Only monomeric anion-radical salts are obtained. Warming up these monomers to 80-160 K results in dimerization polymerization does not take place. The dimer (KCgo)2 is dielectric (Pekker et al. 1995). It has been shown that the tris(anion)-radical Cgo can polymerize too. Particularly, Na2CsCgo forms a polymer that maintains superconducting properties (Mizuki et al. 1994). 

A whole new chemistry has been developed around this discovery, and the unusual properties have given rise to suggestions that it could be made into products for a superconducting material, a three-dimensional polymer, new catalysts, new materials with unusual electrical and optical properties and very high mechanical strength, sensors, nanotubes, nanowires, and so on. At this moment, there are, as yet, no products based on the fullerene on the market. 

The first chemical transformations carried out with Cjq were reductions. After the pronounced electrophilicity of the fullerenes was recognized, electron transfer reactions with electropositive metals, organometallic compounds, strong organic donor molecules as well as electrochemical and photochemical reductions have been used to prepare fulleride salts respectively fulleride anions. Functionalized fulleride anions and salts have been mostly prepared by reactions with carbanions or by removing the proton from hydrofullerenes. Some of these systems, either functionalized or derived from pristine Cjq, exhibit extraordinary solid-state properties such as superconductivity and molecular ferromagnetism. Fullerides are promising candidates for nonlinear optical materials and may be used for enhanced photoluminescence material. 

The discovery of superconductivity [105] in alkali metal doped attracted the attention of a broad cross-section of the scientific community. The composition of the first alkali metal doped fullerene was determined to be [106,107]. In this compoimd, the transition to a superconducting state occurs at = 19.3 K [106]. In a short time, a large variety of alkali metal fullerides M Cgo have been synthesized and studied with respect to their solid-state properties [1, 106-114]. Thereby, the stoichiometries of as well as the alkali metal with M = Na, K, Rb, Cs have... 

CT solids of fullerene Cgo with a number of different inorganic cations have shown metallic or superconducting properties (for superconductivity, see Sect. 5.2.3). Among the fullerene metals, the best known families are MCso anion radical salts... 

Wang P, Metzger RM, Bandow S, Maruyama Y (1993) Superconductivity in Langmuir-Blodgett multilayers of fullerene (Cgo) doped with potassium. J Phys Chem 97 2926—2927... 

Cgo single molecules between electrodes fabricated by electromigration [103] to create single Cgo molecule transistors were measured at a temperature of 40 mK. The results showed the coexistence and competition of the effects of Coulomb repulsion, Kondo correlations and superconductivity [104]. The Kondo effect had been previously observed in similar devices [105]. Recently a SAM of a tricarboxylic acid fullerene derivative was used to fabricate a transistor. The SAM was created by allowing the fullerene compound to self assemble on top of an AI2O3 layer just above the aluminum drain electrode the source lead was created by... 

The first edition of this book published in 1986 was well received by the chemistry and materials science communities and this resulted in the paperback edition published in 1989. We are most gratified by this warm reception to the book which has been found useful by students and teachers as well as practising solid state chemists and materials scientists. Since we first wrote the book, there have been many new developments in the various aspects of solid state chemistry covering synthesis, structure elucidation, properties, phenomena and reactivity. The discovery of high-temperature superconductivity in the cuprates created a great sensation and gave a boost to the study of solid state chemistry. Many new types of materials such as the fullerenes and carbon nanotubes have been discovered. We have now revised the book taking into account the new developments so that it reflects the present status of the subject adequately and points to new directions. 

Potassium-doped LB film prepared from 50 layers of fullerene (C60) and deposited on a polyethylene terephtphalate substrate Microwave absorption or low-field signal Superconductivity was observed at or below 8.1 K 121... 

The solid-state and organic chemistries of fullerenes are currently active areas of research with possible applications, for instance, in the field of superconductivity ( . As illustrated in Fig. 1, more than 3000 papers now have appeared in refereed journals (2). Several excellent reviews summarizing physical (3), solid-state (4), and organic chemis-... 

The MO scheme for the higher fullerenes is similar for example, C70 has a triply degenerate essentially nonbonding LUMO. Anions up to C7o have been made in both solution and the solid state, although the latter do not show superconducting properties. 

---