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The Relative Energies of Ionic Structures for the High‐ T c Superconductor YBa 2 Cu 3 O 7 and Implications for the Superconducting Mechanism
Author(s) -
Floros N.,
Dunne L. J.,
Murrell J. N.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221590225
Subject(s) - superconductivity , copper , condensed matter physics , madelung constant , lattice (music) , ionic bonding , oxygen , ion , lattice energy , degeneracy (biology) , high temperature superconductivity , materials science , physics , chemistry , crystallography , crystal structure , quantum mechanics , acoustics , metallurgy , bioinformatics , biology
Madelung potentials are calculated for several choices of formal oxidation states of the ions in the high temperature superconductor YBa 2 Cu 3 O 7 . For p‐type CuO 2 planes a slightly lower energy is found for a lattice with holes localised on copper (Cu 3+ ) than for one with holes on oxygen (O − ). Moreover, for the lattice with oxygen holes there is a negative energy for electron transfer between neighbouring Cu 2+ O − sites. The near degeneracy of the ‘copper hole’ and ‘oxygen‐hole’ lattices suggests that they should be strongly mixed and this may play some role in the superconductivity behaviour.