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AlO 4 /SiO 4 Distribution in Tetrahedral Double Chains of Mullite
Author(s) -
Schmücker Martin,
Schneider Hartmut,
MacKenzie Kenneth J. D.,
Smith Mark E.,
Carroll Donna L.
Publication year - 2005
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2005.00500.x
Subject(s) - mullite , silicon , oxygen , nmr spectra database , sillimanite , tetrahedron , aluminium , crystallography , materials science , chemistry , spectral line , analytical chemistry (journal) , metallurgy , ceramic , physics , organic chemistry , quartz , astronomy , biotite
The order–disorder of the tetrahedrally coordinated aluminum and silicon atoms in mullite has been investigated by means of 29 Si nuclear magnetic resonance (NMR) spectroscopy. Sinter (3/2) and fused (2/1) mullites in the as‐received state and reheated at 1750°C, and a reference sillimanite were used for this study. All mullites display similar 29 Si NMR spectra: The strongest peak occurs at about −88 ppm, with two subpeaks close to −92 and −96 ppm. The −88 ppm signal is assigned to a sillimanite‐type environment with three aluminum oxygen tetrahedra as next nearest neighbors of the silicon oxygen tetrahedra. The two 29 Si NMR signals near −92 and −96 ppm are assigned to silicon oxygen tetrahedra surrounded by two aluminum oxygen and one silicon oxygen tetrahedra, and one aluminum oxygen and two silicon oxygen tetrahedra, respectively. 29 Si NMR spectra with different short‐range‐order parameters were simulated by an array of 2 × 10 000 tetrahedral positions by means of an adapted random generator. The comparison between measured and simulated mullite and sillimanite 29 Si NMR spectra yields a moderate degree of tetrahedral aluminum–silicon order, with no tendency toward cation demixing.