Ab initio study of effects of substitutional additives on the phase stability of gamma-alumina
2010 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 22, no 50, 505502- p.Article in journal (Refereed) Published
Using ab initio calculations, we have evaluated two structural descriptions of gamma-Al(2)O(3), spinel and tetragonal hausmannite, and explored the relative stability of gamma-Al(2)O(3) with respect to alpha-Al(2)O(3) with 2.5 at.% of Si, Cr, Ti, Sc, and Y additives to identify alloying element induced electronic structure changes that impede the gamma to alpha transition. The total energy calculations indicate that Si stabilizes gamma-Al(2)O(3), while Cr stabilizes alpha-Al(2)O(3). As Si is added, a bond length increase in alpha-Al(2)O(3) is observed, while strong and short Si-O bonds are formed in gamma-Al(2)O(3), consequently stabilizing this phase. On the other hand, Cr additions induce a smaller bond length increase in alpha-Al(2)O(3) than in gamma-Al(2)O(3), therefore stabilizing the a-phase. The bulk moduli of gamma-Al(2)O(3) with these additives show no significant changes. The phase stability and elastic property data discussed here underline the application potential of Si alloyed gamma-Al(2)O(3) for applications at elevated temperatures. Furthermore it is evident that the tetragonal hausmannite structure is a suitable description for gamma-Al(2)O(3).
Place, publisher, year, edition, pages
Institute of Physics , 2010. Vol. 22, no 50, 505502- p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-71473DOI: 10.1088/0953-8984/22/50/505502ISI: 000285049200009OAI: oai:DiVA.org:liu-71473DiVA: diva2:450219