Electrical resistivity, magnetic susceptibility, X-ray photoelectron spectroscopy, and electronic band structure studies of Cu-2.33-xV4O11

摘要

The electronic and physical properties of Cu2.33V4O11 were characterized by electrical resistivity, magnetic susceptibility and X-ray photoelectron spectroscopy (XPS) measurements and by tight-binding electronic band structure calculations. Attempts to prepare Cu2.33-xV4O11 outside its narrow homogeneity range,. The led to a mixture of Cu2.33V4O11, CuVO3 and beta-CuxV2O5. magnetic susceptibility data show no evidence for a magnetic/ structural transition around 300K. The XPS spectra of Cu2.33V4O11, reveal the presence of mixed valence in both Cu and V. The [Cu+]/[Cu2+] ratio is estimated to be 1.11 from the Cu 2p(3/2) peak areas, so [V4+],/[V5+] = 0.56 by the charge balance. Our electronic structure calculations suggest that the oxidation state of the Cu ions is + 2 in the channels of CuO4 tetrahedra, and + 1 in the channels of linear CuO2 and trigonal planar CuO3 units. This predicts that [Cu+]/[Cu2+] = 1.33 and [V4+]/[V-5+] = 0.50, in good agreement with those deduced from the XPS study. (C) 2002 Elsevier Science (USA). [References: 16]