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Studies of the CuO Bond in (Pb, Cd)‐1212 and (Pb, Cd)‐1201 cuprates by X‐ray photoelectron spectroscopy
Author(s) -
Yu W. J.,
Mao Z. Q.,
Tian M. L.,
Wang Y.,
Zhou G. E.,
Zhang Y. H.
Publication year - 1996
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.2221930116
Subject(s) - octahedron , x ray photoelectron spectroscopy , valence (chemistry) , cuprate , chemistry , ion , crystallography , square pyramidal molecular geometry , coordination geometry , atomic orbital , spectral line , octahedral molecular geometry , crystal structure , materials science , molecule , nuclear magnetic resonance , hydrogen bond , physics , doping , optoelectronics , organic chemistry , quantum mechanics , astronomy , electron
It is shown that in (Pb 0.5 Cd 0.5 )Sr 2 (Y 0.5 Ca 0.5 )Cu 2 O 7 and (Pb 0.5 Cd 0.5 )SrLaCuO 5 cuprates, where Cu 2+ ions are in pyramidal and octahedral geometry with five and six neighboring oxygens, respectively, the Cu2p 3/2 (2p 5 3d 10 L) XPS core line is broader than that in Nd 2 CuO 4 where Cu 2+ ions are in a square planar geometry with four coordination oxygen ions, and that for (Pb 0.5 Cd 0.5 )SrLaCuO 5 is the broadest. To explain these changes in the XPS Cu2p 3/2 main line, two different charge transfer mechanisms from the O2p to the Cu3d orbitals are considered. For the square planar geometry (CuO 4 ) only the O2p x , y → Cu3d x 2 − y 2charge transfer is allowed, whereas for pyramidal and octahedral geometries an additional apical O2p z → Cu3d 3 z 2 − r 2transition could take place, and in octahedral geometry the latter transition is more significant. The valence band spectra of the cuprates also confirm this proposition.