Structure and Unusual Magnetic Properties of Mg-Containing Solid Solutions Based on Y2FeTaO7

Mg-containing solid solutions based on Y2FeTaO7 and formed by various mechanisms of heterovalent substitution were synthesized and had the following compositions: Y2Fe0.55Mg0.3Ta1.15O7, Y2Fe0.625Mg0.3Ta1.075O7, Y2Fe0.7Mg0.3TaO7, Y2Fe0.7Mg0.2Ta1.1O7, Y2Fe0.85Mg0.15TaO7, Y1.85Mg0.15Fe0.925Ta1.075O7, and Y1.85Mg0.15FeTaO7. It was shown that all synthesized solid solutions have a pyrochlore-like layered structure (space group P3(1)21), in which Fe3+ ions are distributed over three structural positions. The magnetic properties of these solid solutions are due to the presence of a small ferromagnetic component in a predominantly antiferromagnetic system and characterize a ferrimagnet or a canted antiferromagnet with the Neel transition at the Neel temperature T-N above room temperature. According to the data of magnetic measurements, two magnetic phase transitions to the ordered phase occur in all the studied samples. Along with the T-N transition, in weak magnetic fields and below T-N, there is a second transition, which is most likely due to a spin reorientation of the Morin type. The existence of magnetic ordering at room temperature in one magnetic sublattice or an internal magnetic field (H-in) was confirmed by Mossbauer spectroscopy.

Automated summary

Mg-containing solid solutions based on Y2FeTaO7 were synthesized by various mechanisms of heterovalent substitution. These solid solutions exhibited a pyrochlore-like layered structure and showed ferrimagnetic or canted antiferromagnetic properties above room temperature.