Complex Oxides in the Y2O3–Fe2O3–Ta2O5 System and Their Magnetic Properties

Subsolidus phase equilibria of the Y2O3–Fe2O3–Ta2O5 system were studied. The compound YFeTa2O8 was discovered to exist within a narrow temperature range of 1000–1400°C. Another previously unknown compound, Y2FeTa3O12, appeared to exist in the range up to 1000°C, then it decomposed to YTaO4 and YFeTa2O8. The Y2FeTa3O12 has a pyrochlore-type structure (space group Fd 3 m) with the unit cell parameter a = 10. 3158 (6) Å. The existence of the Y2 – xFe1 + xTaO7 solid solution in the range x = 0–0. 2 was confirmed. The 900 and 1200°C isotherms of the system were designed. The magnetic properties of the YFeTa2O8 and Y2FeTa3O12 phases in fields up to 5000 Oe in the temperature range 2–300 K were studied; their behavior was typical of paramagnets almost over the entire range of temperatures studied. The effects observed at extremely low temperatures indicate the presence of antiferromagnetic interactions, but they are very weak against the background of the paramagnetic matrix.