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Possible New High Temperature Superconductors

IP.com Disclosure Number: IPCOM000103828D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Scott, BA: AUTHOR

Abstract

K-doped C&sub6.&sub0. (denoted "C60" in the following) has recently been found to display superconductivity at about 18K. This molecule is an electron acceptor. Doping it with alkali metals transfers electrons to the lowest lying unoccupied molecular orbitals of the C60 molecule, and the doped material is metallic and superconducting because of &pi.* band formation in the closely packed FCC lattice. There is presently a major effort in isolating and doping fullerenes of higher order (e.g., C70 and beyond).

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Possible New High Temperature Superconductors

      K-doped C&sub6.&sub0.  (denoted "C60" in the following) has
recently been found to display superconductivity at about 18K.  This
molecule is an electron acceptor.  Doping it with alkali metals
transfers electrons to the lowest lying unoccupied molecular orbitals
of the C60 molecule, and the doped material is metallic and
superconducting because of &pi.* band formation in the closely packed
FCC lattice.  There is presently a major effort in isolating and
doping fullerenes of higher order (e.g., C70 and beyond).

      It is the lower order clusters that should be synthesized and
reacted with alkali metals and other types of donors to prepare
conducting and superconducting salts.  In particular, the even
clusters from C58 down to C32 have been observed in molecular beam
experiments.  Alkali-doping or donor salt formation using C32, for
example, should create a solid with a very strong electron-phonon
interaction.  In particular a large breathing mode vibration may be
associated with the molecule, and it might couple strongly to
electrons moving through the mixed valence, narrow band system
created by doping with alkalis and other donors.  C32 appears to be
the lower limit of stability for the fullerene-type clusters, making
it an especially attractive candidate for this type of interaction.

However, in principle, any of the stable, even fullerenes between C32
- C58 could show this behavior provided that the m...