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Ga2.52V2.48O7.33(OH)0.67, a synthetic member of the nolanite/akdalaite-type family of oxyhydroxides containing trivalent vanadium
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Cook, Daniel Sean, Lees, Martin R., Fisher, Janet M., Thompsett, David and Walton, Richard I. (2020) Ga2.52V2.48O7.33(OH)0.67, a synthetic member of the nolanite/akdalaite-type family of oxyhydroxides containing trivalent vanadium. Journal of Solid State Chemistry, 288 . 121396. doi:10.1016/j.jssc.2020.121396 ISSN 0022-4596.
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WRAP-Ga2.52V2.48O7.33OH0.67-synthetic-nolanite-akdalaite-Walton-2020.pdf - Accepted Version - Requires a PDF viewer. Download (1352Kb) | Preview |
Official URL: https://doi.org/10.1016/j.jssc.2020.121396
Abstract
The oxyhydroxide Ga2.52V2·48O7·33(OH)0.67 is prepared by reaction between Ga metal and Na3VO4 in a 1:1 monoethanolamine:water mixture at 240 °C. Powder neutron diffraction shows the material to be isostructural with the minerals nolanite and akdalaite, with cations occupying tetrahedral and octahedral interstitial sites in a hexagonal close-packed array of oxide/hydroxide (P63mc, a = 5.7906(2) Å, c = 9.2550(5) Å). Rietveld refinement against the data shows that Ga preferentially occupies tetrahedral sites, as well as some octahedral sites, and hence all V is octahedrally coordinated. The oxidation state of vanadium is confirmed as close to V3+ using V K-edge X-ray absorption near-edge structure spectroscopy, consistent with the refined chemical composition. The material is metastable, dehydrating around 300 °C and then decomposing above 500 °C, as shown by thermogravimetric analysis and thermodiffraction. The oxide Ga2.52V2.48O8 produced after dehydration at 300 °C is shown to contain a larger proportion of V4+ than the parent oxyhydroxide, to ensure charge balance, but the essential hexagonal structure is maintained. Variable temperature magnetisation measurements show that although both materials appear to obey the Curie-Weiss law at high temperatures, at low temperatures the inverse susceptibility curves are non-linear. There is, however, no evidence for strong magnetic exchange and the extracted effective moments are consistent with the presence of more V3+ in the oxyhydroxide compared to the oxide.
Item Type: | Journal Article | ||||||||
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Subjects: | Q Science > QD Chemistry | ||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry Faculty of Science, Engineering and Medicine > Science > Physics |
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Library of Congress Subject Headings (LCSH): | Gallium compounds, Oxides, Vanadium | ||||||||
Journal or Publication Title: | Journal of Solid State Chemistry | ||||||||
Publisher: | Elsevier | ||||||||
ISSN: | 0022-4596 | ||||||||
Official Date: | August 2020 | ||||||||
Dates: |
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Volume: | 288 | ||||||||
Article Number: | 121396 | ||||||||
DOI: | 10.1016/j.jssc.2020.121396 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||
Date of first compliant deposit: | 21 April 2020 | ||||||||
Date of first compliant Open Access: | 21 April 2021 | ||||||||
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