Al and O substitutions in BaS-phases, Ba2AlxSi12-xN16-xO2+x: A TEM, XRD and solid-state NMR study
2008 (English)In: Solid State Sciences, ISSN 1293-2558, Vol. 10, no 1, 50-60 p.Article in journal (Refereed) Published
In a series of Ba-based oxonitrido-silicate S-phases (Ba2AlxSi12-xN16-xO2+x) spanning a compositional range up to x approximate to 3, we examine the incorporation of Al and O by Si-29 and Al-27 magic-angle spinning (MAS) solid state nuclear magnetic resonance (NMR) and Al-27 triple-quantum MAS (3QMAS). The 3QMAS spectra reveal Al-27 signals from two distinct structural environments, assigned to AlN4 or AlN3O tetrahedra, respectively, and with their relative amounts depending on the S-phase substitution parameter x. Si-29 NMR show variable fractions of SiN4 and SiN3O environments. The NMR results accord overall with a structural substitution model for which O enters at one crystallographic position (occupied according to N4-xOx), in conjunction with a random Al for Si substitution at two distinct crystallographic positions. This leads to S-phase frameworks built from SiN4, SiN3O, AlN4 and AlN3O tetrahedra.
Place, publisher, year, edition, pages
2008. Vol. 10, no 1, 50-60 p.
sialons, oxonitrido-silicates, cation distributions, Si-29 NMR, Al-27 NMR, XRD, TEM
IdentifiersURN: urn:nbn:se:su:diva-59150DOI: 10.1016/j.solidstatesciences.2007.08.018ISI: 000253635500007OAI: oai:DiVA.org:su-59150DiVA: diva2:426271
authorCount :42011-06-232011-06-212011-06-23Bibliographically approved