TEM Characterization of Nanostructured MgAl2O4 Synthesized by a Direct Conversion Process from γ-Al2O3 |
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| Authors: | Jafar F Al-Sharab Frederic Cosandey Amit Singhal Ganesh Skandan James Bentley |
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| Affiliation: | Materials Science and Engineering Department, Rutgers University, Piscataway, New Jersey 08854; NEI Corporation, Somerset, New Jersey 08873; Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6064 |
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| Abstract: | Nanostructured MgAl2O4 spinel was synthesized by a direct conversion process from cubic γ-Al2O3. The effect of post-annealing temperature (300°, 500°, and 800°C) on MgAl2O4 phase formation was investigated using transmission electron microscopy, selected area electron diffraction (SAED), electron energy loss spectroscopy (EELS), and energy-dispersive spectroscopy (EDS). Relative diffraction intensities as well as lattice parameter measurements from SAED revealed that MgAl2O4 spinel structure starts forming at temperatures as low as 300°C. EELS and EDS spectrum images also revealed an increase in elemental homogeneity with increasing annealing temperature. The degree of ordering of Mg and Al between octahedral and tetrahedral sites has been determined from relative diffraction intensities. Results show that annealing to 800°C leads to a spinel phase with an order parameter of 0.78. |
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