caa a22 4500 388022264 CHVBK 20180307124927.0 cr unu---uuuuu 161130e199808 xx s 000 0 eng 10.1557/JMR.1998.0305 doi S0884291400045416 pii (NATIONALLICENCE)cambridge-10.1557/JMR.1998.0305 Characterization of aluminosilicate (mullite) precursors prepared by a mechanochemical process [Elektronische Daten] Aluminosilicate precursors were prepared by mechanochemical treatment of gibbsitesilica gel mixtures. The effect of grinding on their structure and thermal behavior has been examined by 27Al and 29Si MAS NMR, x-ray diffraction (XRD), differential thermal analysis-thermogravimetry (DTA-TG), and Fourier transform infrared (FTIR). After 8 h grinding, the hydrated alumina was completely changed to an amorphous phase which showed a new exothermic DTA peak at about 980 °C due to the formation of γ-Al2O3 or spinel phase. This behavior was related to changes in the Al and Si environments, as deduced from the MAS NMR spectra. With increased grinding time, some 4-coordinated Al appears, together with an Al resonance at about 30 ppm. Simultaneously, a new Si resonance appears at about −90 ppm, indicating a greater degree of homogeneity in the ground samples. Mullite crystallizes at 1200 °C from samples ground for 8-20 h, its XRD intensity increasing with increased milling times, in agreement with the NMR, DTA, and FTIR data. Changes in the Al and Si environments during heat treatment, as reflected by the NMR spectra, are also reported. Copyright © Materials Research Society 1998 Temuujin J. Institute of Chemistry of the Mongolian Academy of Sciences, Ulaanbaatar 51, Mongolia Okada K. Department of Inorganic Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152, Japan MacKenzie K. J. D. New Zealand Institute for Industrial Research and Development, Lower Hutt, New Zealand Journal of Materials Research Cambridge University Press 13/8(1998-08), 2184-2189 0884-2914 13:8<2184 1998 13 JMR https://doi.org/10.1557/JMR.1998.0305 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1557/JMR.1998.0305 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Temuujin J. Institute of Chemistry of the Mongolian Academy of Sciences, Ulaanbaatar 51, Mongolia NATIONALLICENCE 700 1- Okada K. Department of Inorganic Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152, Japan NATIONALLICENCE 700 1- MacKenzie K. J. D. New Zealand Institute for Industrial Research and Development, Lower Hutt, New Zealand NATIONALLICENCE 773 0- Journal of Materials Research Cambridge University Press 13/8(1998-08), 2184-2189 0884-2914 13:8<2184 1998 13 JMR CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge