β-alumina-14H and β-alumina-21R : two chromic Na2-δ(Al,Mg,Cr)17O25 polysomes observed in slags from the production of low-carbon ferrochromium

Hejny, Clivia; Kahlenberg, Volker; Schmidmair, Daniela; Tribus, Martina; De Villiers, J.P.R. (Johan)

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dc.contributor.author	Hejny, Clivia
dc.contributor.author	Kahlenberg, Volker
dc.contributor.author	Schmidmair, Daniela
dc.contributor.author	Tribus, Martina
dc.contributor.author	De Villiers, J.P.R. (Johan)
dc.date.accessioned	2016-09-22T08:09:42Z
dc.date.issued	2016-09
dc.description.abstract	The crystal structures of unknown phases found in slags from the production of low-carbon ferrochromium were studied by powder and single-crystal X-ray diffraction. Two phases of Na2−δ (Al, Mg, Cr)17O25 composition were found to be composed of an alternating stacking of a spinel-type and a Na-hosting block. Similar structures are known for β-alumina and β”- alumina, NaAl11O17. However, the spinel-type block in Na2-δ(Al, Mg, Cr)17O25 is composed of five cation layers in contrast to three cation layers in the β-alumina spinel-block. The two new phases, β-alumina-14H, P63/mmc, a=5.6467(2), c=31.9111(12) Å, and β-alumina-21R, R m, a=5.6515(3), c=48.068(3) Å have a 14-layer and 21-layer stacking with a 2 × (cccccch) and a 3 × (ccccccc) repeat sequence of oxygen layers in cubic and hexagonal close packing, respectively.	en_ZA
dc.description.department	Electrical, Electronic and Computer Engineering	en_ZA
dc.description.embargo	2017-09-30
dc.description.librarian	hb2016	en_ZA
dc.description.uri	http://www.elsevier.com/locate/jssc	en_ZA
dc.identifier.citation	Hejny, C, Kahlenberg, V, Schmidmair, D, Tribus, M & De Villiers, JPR 2016, 'β-alumina-14H and β-alumina-21R : two chromic Na2-δ(Al,Mg,Cr)17O25 polysomes observed in slags from the production of low-carbon ferrochromium', Journal of Solid State Chemistry, vol. 241, pp. 70-78.	en_ZA
dc.identifier.issn	0022-4596
dc.identifier.other	10.1016/j.jssc.2016.05.038
dc.identifier.uri	http://hdl.handle.net/2263/56879
dc.language.iso	en	en_ZA
dc.publisher	Elsevier	en_ZA
dc.rights	© 2016 Elsevier Inc. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Journal of Solid State Chemistry. 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. A definitive version was subsequently published in Journal of Solid State Chemistry, vol. 241, pp. 70-78, 2016. doi : 10.1016/j.jssc.2016.05.038.	en_ZA
dc.subject	β-alumina	en_ZA
dc.subject	Polysome	en_ZA
dc.subject	Crystal structure	en_ZA
dc.title	β-alumina-14H and β-alumina-21R : two chromic Na2-δ(Al,Mg,Cr)17O25 polysomes observed in slags from the production of low-carbon ferrochromium	en_ZA
dc.type	Postprint Article	en_ZA