L.P. Mezentseva

Phase relations in the ZrO2-FeO system

We present the results of the investigation of the ZrO2-FeO system under an inert atmosphere. We have refined the position of the eutectic point, which lies at 1332 ± 5°C and 10.3 ± 0.6 mol % ZrO2. The iron oxide solubility boundaries in zirconium dioxide have been determined over a wide temperature range taking into account the polymorphism in ZrO2. A phase diagram for the system has been designed.

Phase and chemical transformations in the SiO2-Fe2O3(Fe3O4) system at various oxygen partial pressures

The SiO2-Fe2O3(F3O4) system has been studied in air, oxygen, and an inert atmosphere. The dissociation temperatures for iron oxides, the onset and full melting temperatures for coexisting phases, and the melt demixing temperatures have been determined as a function of the oxygen partial pressure. A scenario of the phase and chemical transformations in the title systems has been developed.

Phase transformation in the binary section of the UO2-FeO-Fe system

Phase transformations in the oxide binary section of the UO2-FeO-Fe ternary system were studied. The melting onset point of the UO2-FeO heterogeneous system (1335±5°C) was determined and the fusion curve of this system was constructed. The limiting solubility of FeO in the UO2 solid solution was measured. The changes in crystal parameters in formation of the solid solution were determined. Uranium dioxide was found to be insoluble in the wüstite phase (FeO).

Ternary eutectics in the systems FeO-UO2-ZrO2 and Fe2O3-U3O8-ZrO2

The systems FeO-UO2-ZrO2 (in inert atmosphere) and Fe2O3-U3O8-ZrO2 (in air) were studied. For the FeO-UO2-ZrO2 system, the eutectic temperature was found to be 1310°C, with the following component concentrations (mol %): 91.8 FeO, 3.8 UO2, and 4.4 ZrO2. For the Fe2O3-U3O8-ZrO2 system, the eutectic temperature was found to be 1323°C, with the following component concentrations (mol %): 67.4 FeO1.5, 30.5 UO2.67, and 2.1 ZrO2. The solubility limits of iron oxides in the phases based on UO2(ZrO2,FeO) and UO2.67(ZrO2,FeO1.5) were determined.