Phase evolution of vanadium oxides obtained through temperature programmed calcinations of ammonium vanadate in hydrogen atmosphere and their humidity sensing properties

Akande, A.A.; Linganiso, E.C.; Dhonge, B.P.; Rammutla, K.E.; Machatine, Augusto Gonçalo Jose; Prinsloo, Linda Charlotta; Kunert, Herbert W.; Mwakikunga, B.W.

dc.contributor.author	Akande, A.A.
dc.contributor.author	Linganiso, E.C.
dc.contributor.author	Dhonge, B.P.
dc.contributor.author	Rammutla, K.E.
dc.contributor.author	Machatine, Augusto Gonçalo Jose
dc.contributor.author	Prinsloo, Linda Charlotta
dc.contributor.author	Kunert, Herbert W.
dc.contributor.author	Mwakikunga, B.W.
dc.date.accessioned	2015-03-05T09:02:45Z
dc.date.available	2015-03-05T09:02:45Z
dc.date.issued	2015-02
dc.description.abstract	The possibility of obtaining vanadium dioxide (VO2) [wherein the vanadium ionic state is 4þ] from a precursor of ammonium metavanadate (NH4VO3) bearing the ion V5þ is investigated. The reduction is carried out by calcining the NH4VO3 powders in similar concentrations of H2 flow at varying temperatures. The resulting powders have been studied by several techniques including XRD, Raman spectroscopy, FTIR, TEM, BET and DSC. It is found that remnants of bright yellow V5þ still exist up to calcination temperatures of 100 C after which the sky-blue VO2 dominates at calcination temperatures of 150 C e250 C. There is a population surge of metastable dark-blue V6O13 (where V is in between V4þ and V5þ ionic states) between 250 C and 300 C. However above 350 C the material reverts to the stable V5þ in the yellow-orange V2O5. XPS/EDS and VSM confirm the order of appearance to be VO2(150 C) / V6O13(200 C) / V2O5 (350 C).	en_ZA
dc.description.librarian	hb2015	en_ZA
dc.description.sponsorship	India-Brazil-South Africa trilateral cooperation under the National Research Foundation (NRF) grant number HGER24X.	en_ZA
dc.description.uri	http://www.elsevier.com/locate/matchemphys	en_ZA
dc.identifier.citation	Akande, AA, Linganiso, EC, Dhonge, BP, Rammutla, KE, Machatine, AGJ, Prinsloo, LC, Kunert, HW & Mwakikunga, BW 2014, 'Phase evolution of vanadium oxides obtained through temperature programmed calcinations of ammonium vanadate in hydrogen atmosphere and their humidity sensing properties', Materials Chemistry and Physics, vol. 151, no. 206-2015.	en_ZA
dc.identifier.issn	0254-0584
dc.identifier.other	10.1016/j.matchemphys.2014.11.055
dc.identifier.uri	http://hdl.handle.net/2263/43873
dc.language.iso	en	en_ZA
dc.publisher	Elsevier	en_ZA
dc.rights	© 2014 Elsevier B.V. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Materials Chemistry and Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials Chemistry and Physics, vol. 151, pp. 206-215, 2015. doi : 10.1016/j.matchemphys.2014.11.055.	en_ZA
dc.subject	Annealing	en_ZA
dc.subject	Oxidation	en_ZA
dc.subject	Phase transition	en_ZA
dc.subject	Thermogravimetric analysis	en_ZA
dc.subject	X-ray diffraction (XRD)	en_ZA
dc.subject	Topology	en_ZA
dc.subject	Adsorption	en_ZA
dc.subject	Desorption	en_ZA
dc.subject	Differential scanning calorimetry (DSC)	en_ZA
dc.subject	X-ray photo-electron spectroscopy (XPS)	en_ZA
dc.subject	Vibrating sample magnetometer (VSM)	en_ZA
dc.title	Phase evolution of vanadium oxides obtained through temperature programmed calcinations of ammonium vanadate in hydrogen atmosphere and their humidity sensing properties	en_ZA
dc.type	Postprint Article	en_ZA