Electron spin resonance of defect-rich vanadium oxide nanotubes

Abstract

We have studied defect-rich vanadium oxide nanotubes, with reduced V4+ concentration, by means of x-ray diffraction, infrared spectroscopy, x-ray photoemission spectroscopy, and electron spin resonance (ESR) measurements. In particular, prominent anomalies at 320 and 370 K attributed to structural phase transitions were manifest in the ESR measurements. The ESR spin susceptibility exhibited a singlet-triplet transition of the spin dimers and an antiferromagnetic exchange coupling. In the high-temperature region above 370 K, where the two distinct ESR lines merged, an activation energy of the fast hopping polaron motion, 0.48 eV, was obtained. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3208066]