SINTHESIS CERIUM-CONTAINING SOLID SOLUTIONS BASED ON HAFNIUM SILICATE USING MECHANICAL ACTIVATION

The processes occurring during the synthesis of Ce-containing solid solutions based on hafnium silicate by the solid-phase method using mechanical activation were studied. Mechanical activation of a mixture of silicon, hafnium and cerium oxides with a molar ratio of SiO2 : HfO2 : CeO2 = 1 : 0,9 : 0,1 was carried out in a laboratory planetary mill AGO-2 at a centrifugal factor of 40 g for 10 min. Reactive hafnium and cerium oxides were used in this work. Reactive hydrated silica and silica obtained from the slag of the “Pechenganikel” plant were used as a silica-containing component. Under identical synthesis conditions, similar results were obtained for both starting compositions. Using X-ray diffraction analysis, it was shown that after calcination of mechanically activated mixtures of oxides at 1200–1400 °C, the main phase was HfSiO4 (hafnon) with a tetragonal crystal lattice, containing an isomorphous inclusion of cerium. A hafnium-containing solid solution based on cerium dioxide (cerianite) was present as an impurity phase. Using the Rietveld method, the compositions of phases in calcined mixtures were calculated, as well as the compositions of the resulting solid solutions based on Vegard's law.