Synthesis and characterization of pure nanocrystalline magnesium aluminate spinel powder

Synthesis of nanocrystalline magnesium aluminate spinet (MgAl2O4) by mechanical activation of a powder mixture containing Al2O3 and MgCO3 with subsequent annealing was investigated. Simultaneous thermal analysis (STA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were utilized to characterize the as-milled and annealed samples. Results showed that pure nanocrystalline spinet could be fabricated completely by 5 h of mechanical activation with subsequent annealing at 1200 degrees C for 1 h with a crystallite size of about 45 nm. Further milling had no significant effects on structure or phase composition of spinet phase after subsequent annealing. The nanocrystalline spinet powder obtained after 60h of milling and subsequent annealing at 1200 degrees C for I h had a crystallite size of about 25 nm according to Williamson-Hall approach and particle sizes smaller than 200 nm. Enhanced mechanical properties were observed in samples prepared from the powder mixture and milled for a longer period. (C) 2009 Elsevier B.V. All rights reserved.