The correlation between the p-type hole conduction and the electronic structures of Cr-deficient CuCr 1-x O 2 (x=0-0.1) compounds was investigated using O K-, Cu, and Cr L 3,2 -edge x-ray absorption near-edge structure (XANES), scanning photoelectron microscopy, and x-ray emission spectroscopy measurements. XANES spectra reveal a gradual increase in the Cu valence from Cu1 + to Cu2 + with increasing Cr deficiency x, whereas, the valence of Cr remains constant as Cr3 + . These results indicate that the p-type conductivity in the CuCr 1-x O 2 samples is enhanced by a Cu1 + -O-Cu2 + rather than a Cr3 + -Cr4 + or direct Cu1 + -Cu2 + hole mechanism. Remarkable Cr-deficiency-induced changes in the densities of Cu 3d, Cu 3d-O 2p, and O 2p states at or near the valence-band maximum or the Fermi level were also observed. In addition, a crossover of conduction mechanism from thermally activated (TA) hopping to a combination of TA and Mott's three-dimensional variable range hopping occurs around 250 K.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2012 Dec 7|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics