W.M. Walsh, F. Wudl, et al.
Physical Review Letters
The difference in Madelung site potential, VM, between a hole on a copper site and one on an oxygen site can control the holes site preference and ability to delocalize. Among a variety of copper oxide structures, eVM is shown to vary by 3 eV and to clearly separate two classes of compounds: Those with eVM>47 eV are metallic with high Tc and delocalized holes, whereas those with lower "VM are semiconducting because their holes are self-trapped on oxygen. © 1989 The American Physical Society.
W.M. Walsh, F. Wudl, et al.
Physical Review Letters
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Solid State Communications
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Powder Diffraction
P. Batail, S.J. LaPlaca, et al.
JACS