SYNTHESIS OF MAGNESIUM ALUMINATE SPINEL NANOPARTICLES BY CO-PRECIPITATION METHOD: THE INFLUENCES OF PRECIPITANTS

Magnesium Aluminate Spinel (MgAl2O4) nanoparticles were synthesized by the co-precipitation method using 2 different precipitants, i.e., urea and ammonium bicarbonate. The precipitated precursor synthesized using urea as a precipitant was a platelet-like hydrotalcite (Mg6Al2CO3(OH)(16)center dot 4H(2)O). The hydrotalcite decomposed to MgO and an amorphous phase after calcining at 600 degrees C for 2 h. The formation of MgAl2O4 via a reaction between MgO and the amorphous phase was observed after calcining over 800 degrees C for 2 h, while the precipitated precursor synthesized using ammonium bicarbonate as a precipitant was an unidentified low crystalline phase. The precipitated precursor decomposed to an amorphous phase after calcining at 600 degrees C for 2 h. MgA(2)O(4) was obtained after calcining over 800 degrees C for 2 h. In addition, after calcining at 1100 degrees C for 2 h, the equiaxed MgAl2O4 nanoparticles with a particle size in the range of 10 to 30 nm were obtained from both methods. However, the MgAl2O4 nanoparticles synthesized using ammonium bicarbonate as a precipitant exhibited a higher specific surface area (74.61 m2/g).