Influence of tetraethylammonium bromide on phase inhomogeneity of dispersevanadium dioxide particles in matrix of polyethylene glycol

A study has been made on samples of disperse vanadium dioxide (VO2) in a ma trix (M = 1500) of polyethylene glycol (PEG) doped with a quaternary ammoni um salt (QAS), namely, tetraethylammonium bromide. It has been established that under the influence of the dopant, the heating of a sample up to the t emperature of the metal-semiconductor phase transition (MSPT) results in a phase inhomogeneity of the sample. One portion of the disperse VO2 particle s passes to the metallic state, while others retain its semiconducting stat e. The possible cause for the observed phenomenon is the emergence of stron g local electric fields between the QAS cations and the VO2 surface. In the region of phase heterogeneity, the MSPT temperature for the semiconducting phase is shifted into a higher temperature interval. (C) 2000 Elsevier Sci ence B.V. All rights reserved.