High purity (AR grade) ferric chloride, aluminium chloride,
acetylacetonate and sodium acetate were obtained from commercial
sources (Sigma–Aldrich). Iron(III) acetylacetonate complex
[Fe(acac)3] was synthesized in the following manner. 2.9648 g
of ferric chloride was dissolved in 25 ml of water. A solution of
20.053 g of sodium acetate trihydrate in 25 ml of water was added
to it followed by addition of 5.489 g of acetylacetone. The flask
was covered and the mixture was stirred at room temperature for
20–30 min. The solid product (bright red precipitate) was collected
by suction filtration. It was washed with 0.5 ml water and dried
thoroughly in air. The melting point of the complex was 182 ◦C.
Aluminium(III) acetylacetonate complex [Al(acac)3] was synthesized
using similar method and its melting point was 190 ◦C. To
synthesize FeAl2O4 nanoparticles, a mixture of Fe(acac)3 (0.41 g,
1.18 mmol) and Al(acac)3 (0.38 g, 1.18 mmol) was heated in a furnace
under nitrogen at 450 ◦C for 3 h. The product was black in
color.