The electronic structures of SrCu2O2 and PbCu 2O2 have been studied by density functional theory calculations in conjunction with high resolution X-ray photoemission spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR). In both materials there is linear O-Cu-O coordination and a band of Cu 3d states sits above a band of O 2p states, but with strong hybridisation between the two. The Pb ions in PbCu2O2 introduce new states of dominant Pb 6s atomic character below the bottom of the O 2p valence band together with states of mixed Pb 6s, O 2p and Cu 3d character at the top of the O 2p valence band. Hole states introduced by K doping in PbCu2O2 are shown to reside in anisotropic sites with clearly defined hyperfine couplings to 63Cu as revealed by EPR. Broadening of the EPR signal in K-doped SrCu2O2 is associated with averaging of the g value and Cu hyperfine anisotropy due to facile hole hopping. It is concluded that replacement of Sr with Pb does not facilitate delocalisation of the holes.
All Science Journal Classification (ASJC) codes
- Materials Chemistry