The purpose of this work is to synthesize a single phase spinel from a layered magnesium-iron(II)-iron(III) hydrotalcite precursors. This paper reports a systematic investigation of the preparation of Mg- Fe(II)-Fe(III) hydrotalcites, and several hydrotalcites with different Mg~(2+)/Fe~(2+)/Fe~(3+) molar ratios in the layers were obtained. When the Mg~(2+)/Fe~(2+)/Fe~(3+) molar ratio in the stock solution is equal to 1/2/1, 4/5/3 or 2/1/1, a well crystallized hydrotalcites were obtained. The effects of various reaction conditions on the crystal structure were also investigated. The hydrotalcites were characterized by XRD, VSM and Mossbauer spectroscopy. When the Mg~(2+)/Fe~(2+)/Fe~ (3+) molar ratio in the reaction mixture was 2/1/1, the material obtained by calcining the resulting hydrotalcite was a single phase spinel.

Key words: SPINEL, MAGNESIUM, IRON, HYDROTALCITE, COPRECIPITATION, MAGNETISM, SOFT MAGNETIC MATERIALS, ROASTING, X-RAY DIFFRACTION, MOSSBAUER SPECTROSCOPY