Abstract: Magnesium aluminate spinel was prepared by solid-state reaction method with light burned magnesia powder, MgCO₃ or analytically pure Mg(OH)₂ as MgO source and nano-η-Al₂O₃ with molar ratio of 1∶1. The effects of different MgO sources on the apparent porosity, bulk density, phase composition, unit cell parameters and microstructure of magnesium aluminate spinel prepared by nano-η-Al₂O₃ were studied. The results show that with the increase of sintering temperature, the compactness of the magnesium aluminate spinel samples prepared by three kinds of MgO sources and nano-η-Al₂O₃ becomes better and better. At 1 600 ℃, the maximum bulk density of spinel samples prepared by using Mg(OH)₂ as MgO source and nano-η-Al₂O₃ is 3.296 g/cm³, the lowest apparent porosity is 1.9%, and the grain size is about between 3 μm and 5 μm. At 1 300 ℃, all the three MgO sources and nano-η-Al₂O₃ form magnesium aluminate spinel. Compared with the traditional solid-phase method, for preparing magnesium aluminate spinel with α-Al₂O₃ as Al₂O₃ source, the synthesis temperature of magnesium aluminate spinel is reduced by 100 ℃. It reduces the cost of magnesium aluminate spinel, which has practical significance for the application of magnesia alumina spinel.

Key words: nano-η-Al₂O₃, magnesium aluminate spinel, sintering temperature, solid state reaction method