<p>Magnetic materials based on ferrite earth-metal elements have high electrical resistivity (104 107 Ohm) and high coercive force (500 kA / m). In this case, the magnetization values of saturation strongly depend on the size of the domains (crystallites). The microstructure as well as the crystallite size of the structured material depend on the technological conditions of the synthesis. Therefore, the control of the microstructure (crystallite size) of the material enables to vary the magnetic properties of the material, since the study of the synthesis of magnetic materials from the melt seems relevant both in fundamental and applied aspects. The purpose of the work is to study the processe of synthesis of magnetic materials – barium ferrites by melting the mixture of initial reagents in the Large Solar Furnace. The methods of X-ray structural analysis, microscopy and the measurements of the physical parameters of the material have been used. The study deals with the formation of the barium hexagonal ferrite 4(Fe2 O3 )4(FeO)BaFeO3-X and the cubic Ba3 Fe2 O6-X= 2(BaО)FeОВаFeO3-X, tetragonal BaOFeOBaFeO3-X modifications due to the exposure of concentrated solar radiation of high (350W/cm2) density on BaCO3 +Fe2 O3 mixture,. The modification of the technological process makes possible to obtain a material with high parameters of electrical resistance 1010 Ohm • cm, density 5 g / cm3, magnetodielectric effect 4.1%. Such materials can be used in electronic circuits to stabilize the frequency, current and voltage amplitude.</p>