Abstract
Mullite is an aluminosilicate of the composition Al2(Al212xSi222x)O102x with x generally ranging between 0.2 and 0.5. XRD and 29 Si and 27 Al nuclear magnetic resonance (NMR) have been used to investigate the structure of various mullite compositions ( x 5 0.26, 0.36, 0.42, and 0.69) as well as sillimanite (x 5 0) and g-Al2O3 (x 5 1). 27 Al magic angle spinning (MAS) NMR of the central and satellite transitions have been used to determine the chemical shifts and quadrupole interaction parameters for the various AlO 4 and AlO6 units. The isotropic chemical shifts of the various units are 5.9 ppm for AlO 6, 69.1 ppm for AlO4(T), 55.0 ppm for AlO4(T9), and 45.7 ppm for AlO4(T*) where AlO4(T) denotes the aluminum tetrahedra in the double chains, and AlO4(T9) and AlO4(T*) those next to the oxygen Oc*. Quantitative numbers of the aluminum occupancy of these sites have been determined for the various powder samples. These results are in good agreement with the average structure model of mullites. NMR and XRD proved the presence of impurities of kyanite in natural sillimanite and of g-Al2O3 in the mullites with x 5 0.42 and 0.69.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
