Tem Study Of Nanostructured Magnesium Aluminate Spinel Phase Formation

The direct conversion of nanostructured MgAl2O4 spinel from gamma-Al2O3 has been investigated using three different initial nanostructured powders with differing particle size and agglomerate size. The effect of post-annealing temperature (300, 500 and 800degreesC) on MgAl2O4 phase formation was investigated using Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED), Relative diffraction intensities as well as lattice parameter measurements revealed that MgAl2O4 spinel structure starts forming at temperatures as low as 300degreesC. Further annealing to 800degreesC and 850degreesC leads to pure spinel phase with limited particle growth. Data suggests that pure MgAl2O4 phase formation is favored by small initial gamma-Al2O3 particle size as well as small primary agglomerate size.