Complex Oxides in the System and Their Magnetic Properties

Phase equilibria in the suboxides region of the YO–FeO–TaO system have been studied. The compound YFeTaO was discovered for the first time, existing in a narrow temperature range of 1000–1400°C. Another previously unknown compound, YFeTaO, is realized in the temperature range up to 1000°C, at which it decomposes into YTaO and YFeTaO. It has been established that YFeTaO belongs to the structural type of pyrochlore (sp. gr. Fd3m) and has lattice parameter = 10.3158(6) Å. The existence of a solid solution of YFeTaO in the range = 0–0.2 has been confirmed. Isothermal sections of the system have been constructed for temperatures of 900 and 1200°C. The magnetic properties of the YFeTaO and YFeTaO phases in fields up to 5000 Oe in the temperature range 2–300 K have been studied and it has been shown that their behavior in almost the entire studied temperature range is characteristic of paramagnets. At extremely low temperatures, effects have been found indicating the presence of antiferromagnetic type interactions, but they are very weak against the background of a paramagnetic matrix.