An electrochemical method for the synthesis of complex dispersed oxide system Al 2 O 3-Fe 2 O 3 , based on the combined aluminum and iron anodic dissolution in aqueous solution containing chloride ions, has been suggested. The phase composition and morphology of Al 2 O 3-Fe 2 O 3 dispersed precipitate have been investigated by means of X-ray fluorescence, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The influence of the electrolysis mode on the characteristics of the synthesized oxide system has been shown. It is found that the direct current (DC) mode allows us to adjust the phase correlation in the precipitate and to obtain a particle size which is two or more times smaller than the particle size of the samples synthesized by means of the alternating current (AC).

The process of anodic dissolution of iron (purity not less than 99%) in aqueous solutions of barium chloride, barium nitrate and binary electrolytes under galvanostatic conditions and by registration of potentiodynamic polarization curves was investigated. The influence of solution composition and concentration and the value of applied direct current on the intensity of anodic oxidation of iron was shown. It was revealed that the oxidation rate of metal in binary electrolytes containing barium chloride and barium nitrate is comparable with the intensity of anodic dissolution in a solution based on barium chloride. It was found that anodic polarization curve in solutions containing BaCl2 and Ba(NO3)2 has a complex form typical of passivated metals. There is a clear maximum of anodic oxidation current on this curve, as well as in barium nitrate solution, however the peak height is much higher (50-150 times). A method for the synthesis of dispersed barium ferrite, based on the anodic oxidation of iron in aqueous barium chloride and barium nitrate solutions with subsequent thermal treatment of the product of electrochemical dissolution was suggested. The phase and elemental composition and structural characteristics of obtained precursor and ferrite samples were examined using X-ray phase analysis. The influence of the heat treatment mode on the phase composition of the synthesized samples is shown. It is found that electrolysis with a soluble iron electrode using direct anode current in 0.05M BaCl2 + 0.5M Ba(NO3)2 solution and subsequent thermal treatment of the dissolution product at 1200 ° C provide the formation of dispersed system, whose phase composition is predominantly Ba0.87Fe11.08O17.15 (74%) and BaFe2O4 (17%).

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Aims: Anodic polarization behavior of a combined iron-titanium electrode (two metals in electrical contact with each other) in aqueous solutions containing halide ions (F- and Cl-) was studied. Methods: The joint anodic dissolution of titanium and iron with subsequent thermal treatment makes it possible to obtain precursors of a highly dispersed mixed oxide system Fe2O3-TiO2. The phase and elemental composition and structural characteristics of obtained products were examined by means of X-ray diffraction and scanning electron microscopy. It has been experimentally confirmed that via changing the anode current density, hydrofluoric acid concentration in electrolyte and ratio of the working surface area of contacting metals, it is possible to effectively control the rate of anodic reactions and phase composition and morphology of anodic oxidation products for iron and titanium components in a combined electrode. Results: The main results of this study are following: Electrochemical method for the synthesis of complex dispersed oxide system Fe2O3 based on joint anodic oxidation of contacting metals in aqueous media was suggested. Relationships between parameters of electrochemical process and characteristics of the synthesized oxide system were revealed. Conclusion: By varying the parameters of the electrolysis process, it is possible to prepare complex oxyhydroxides with different ratios of iron and titanium, which makes it possible to synthesize precursors of iron titanates of preset composition and structure.