Sonochemical Synthesis of Amorphous Iron

Furthermore, amorphous materials possess high flexibility with regard to the fine-tuning of electronic properties, mainly due to the fact that thermodynamic constraints are less severe in supercooled liquids than in crystalline materials. They are also ideally chemically homogeneous, structurally isotropic and highly reactive owing to their metastable structure. 

The main problem encountered in the use of such materials is their preparation.20 Usually, the melt-quenching method, with a cooling rate of at least 10 -10 K s , is the more frequently used (for comparison, plunging red-hot steel into water occurs with cooling rates of only ca. 2500 K s ). Moreover, the products obtained are ribbons, several millimeters to several centimeters wide with a thickness of several nanometers with a completely non-porous structure. 

Ultrasonic irradiation of iron pentacarbonyl, either pure or as 4.0-M solutions in decane with a high-intensity 20-kHz probe at 100 W cm 2, yields a dull black powder.2 /22 Elemental analysis of the product gives a 96% iron composition 

13 Nagata, Y. Watanabe, Y. Fujita, S. Dohmaru, T. Taniguchi, S. /. Chem. Soc. Chem. Commun. 1992,1620-1622. 

19 Oelhafen, P. in Glassy Metals II (Beck, H Giintherodt, G. Eds.), Springer, Berlin, 1983, pp. 283-321. 

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Suslick KS, Choe SB, Cichowlas AA, Grinstaff MW (1991) Sonochemical synthesis of amorphous iron. Nature 353 414-416... 

Suslick, K. S. Choe, S. B. Cichowlas, A. A. Grinstaff, M. W. (1991). Sonochemical synthesis of amorphous iron. Nature, 353,414-416,0028-0836 Taubert, A. Li, Z. (2007). Inorganic materials from ionic liquids. Dalton Trans. 7, 7 SC72 J, 1477-9226... 

Pinkas J, Reichlova V, Zboril R, Moravec Z, Bezdicka P, Matejkova J (2008) Sonochemical synthesis of amorphous nanoscopic iron (III) oxide from Fe(acac)3. Ultrason Sonochem... 

Pinkas, J., Reichlova, V., Serafimidisova, A., Moravec, Z., Zboril, R., Jandk, D., and Bezdicka, P. (2010) Sonochemical synthesis of amorphous yttrium iron oxides embedded in acetate matrix and their controlled thermal crystallization toward garnet (Y3FesOi2) and perovskite (YFeOs) nanostructures. /. Phys. Chem. C, 114,13557 13564. 

Sonochemical synthesis of fxmctionalized amorphous iron oxide nanoparticles. Langmuir, 17 5093-5097. 

Two approaches for the synthesis of nanostructured M50 type steel (composed of 4.0% Cr, 4.5% Mo, 1.0% V, 0.8% C and balance Fe) powders and their consolidation are reported in this chapter. One approach involved the sonochemical decomposition of organometallic precursors and the other involved the reduction of the metal halides with lithium triethyl borohydride followed by vaccum sublimation of the powders to remove lithium chloride. The as-synthesized powders are amorphous by X-ray diffraction (XRD) but the peaks corresponding to bcc a-Fe are observed in the compacts. The morphology and composition of the powders synthesized by both techniques, as well as the compacts, were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Hardness, density, particle size and impurity contents were also determined for the compacts. In addition, pure nanosized iron particles obtained by the ultrasound decompositon of iron pentacarbonyl were consolidated and the properties of the latter were studied. 

The first applications of DDM in the structural studies of polycrystalline and mesostructured substances have demonstrated its capacities for obtaining precise structure characteristics from diffraction data with various background complexities. DDM was used in the structure refinement and analysis of a series of nickel and iron methylimidazole hexafluorophosphates and tetrafluoroborates obtained in a sonochemical reaction. Due to the specific synthesis procedure, the substances were highly disordered and their XRD powder patterns contained a background of complex curvature, indicating the presence of an amorphous admixture. Despite these difficulties, the structures were successfully refined by DDM and analyzed in detail. 

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