Frolova L. Physico-chemical bases of hydrophase technology of production of spinel ferrites of 3d-metals

The dissertation is devoted to the development of scientific bases of hydrophase technology of obtaining ferrites 3d-metals of different composition, principles of regulation and forecasting of their magnetic, photocatalytic properties. It is established that the process of coprecipitation of hydroxides of iron(II) and cobalt(II), nickel(II), manganese(II), zinc, copper(II) hydroxides is associated with the formation of aqueous complexes and the formation of a structure different stability. The mechanism of ferritization under the action of contact nonequilibrium low-temperature plasma (CNP) is proposed and experimentally substantiated. The degree of homogeneity and crystallinity of ferrites formed under conditions of their further oxidation decreases in the following order: Fe2+ > Zn2+ > Ni2+ > Co2+ > Mn2+ > Cu2+. It is determined that in the systems Со2+-Fe2+-SO42--ОН-, Ni2+-Fe2+-SO42--ОН- and Ni2+-Со2+-Fe2+-SO42--ОН- the saturation of the magnetization significantly depends on the pH of processing, temperature and processing time of CNP. The main factor of influence is the initial pH of the treated suspension, due to the possibility of adjusting the oxidation rate. Crystal chemical models for ferrites MxFe3-xO4, where M = Ni, Co, are proposed, and it is found that the degree of spinel inversion increases with increasing value of x. Influence of cation content on phase composition, structural characteristics, magnetic and photocatalytic properties of ferrites in ternary systems CoxNiyZn1-x-yFe2O4, CoxNiyMn1-x-yFe2O4, CoxZnyMn1-x-yFe2O4, NiyZnxMn1-x-yFe2O4 (were 0<x<1 and 0<y<1) is established. The maximum photocatalytic activity corresponds to the total composition of MI0,33МII0,67Fe2O4, where MII = Zn, Mn, MI= Co, Ni. Physico-chemical bases of technology of production of 3d-metal ferrites are created. An effective technological scheme has been developed.