Structural transformation of a $(1-x)$Fe$_{2}$O$_{3}$-$x$RuO$_{2}$ nanosystem at different reduction temperatures

The phase composition and structure of oxide and hydrogen-reduced iron–ruthenium systems are studied using conversion and adsorption Mössbauer spectroscopy, as well as X-ray diffraction methods. In samples with metal concentration (mass.%) 50Fe–50Ru after calcination in air at 773 and 973 K, nanosystems containing two phases with different degrees of dispersion are formed ($\alpha$-Fe$_{2}$O$_{3}$ with an admixture of Ru and RuO$_2$ with an admixture of Fe, respectively). Structural transformations of the nanosystem calcinated at 973 K in different reduction conditions are investigated. It is shown that the formation of nanostructures depends on the initial and final reduction temperatures. The presence of ruthenium substantially changes the reduction kinetics of oxide systems. It is shown that upon an increase in the reduction temperature, the rearrangement of initial stoichiometric oxides to intermediate oxide structures with varying compositions and with different crystal lattice types is observed. The terminating stage of reduction is the formation of metal clusters or solid solutions of intermetallides.