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This article presents a simple and fast method to synthesize metal fluorides such as FeF 2 , CoF 2 , ZnF 2 , LaF 3 , YF 3 , SrF 2 , and metal oxide Fe 2 O 3 having different morphologies. The synthesis is carried out in an ionic liquid solvent using a domestic microwave oven. The products are characterized with the help of an X-ray diffraction method. The different morphologies of the products are studied with the help of a high-resolution transmission electron microscope and a high-resolution scanning electron microscope. The change in the oxidation state of the reactant Fe(III) to the product Fe(II) is confirmed through Mo ¨ssbauer studies. The presence of carbon and its application as a reducing agent is illustrated by Raman spectroscopy.

Nanosized amorphous NiFe 2 O 4 powder was prepared by sonochemical decomposition of solutions of volatile organic precursors, Fe(CO) 5 and Ni(CO) 4 , in decalin at 273 K, under an oxygen pressure of 100-150 kPa. The amorphous nature of these particles was confirmed by various techniques, such as SEM, TEM, electron microdiffraction, and X-ray diffractograms. Magnetic measurements, Mössbauer, and EPR spectral studies indicated that the as-prepared NiFe 2 O 4 ferrite particles were superparamagnetic. The Mössbauer spectrum of the crystallized sample showed a clear sextet pattern, with hyperfine field values of 500 and 508 kOe for A (tetrahedral) and B (octahedral) sublattices, respectively, of the inverse spinel NiFe 2 O 4 . Saturation magnetization of the annealed sample (25 emu/g) was significantly lower than that for the reported multidomain bulk prticles (55 emu/g), reflecting the ultrafine nature of the sample. Thermogravimetric measurements with a permanent magnet gave Curie temperatures of 440°C for amorphous and 560°C for the crystallized forms.

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