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

• Published in: Russian journal of inorganic chemistry 2023-10, Vol.68 (10), p.1325-1333
• Main Authors: Ellert, O. G., Popova, E. F., Kirdyankin, D. I., Imshennik, V. K., Kulikova, E. S., Egorysheva, A. V.
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Chemistry; Chemistry and Materials Science; Ferrimagnets; Ferromagnetism; Inorganic Chemistry; Magnetic fields; Magnetic measurement; Magnetic properties; Mossbauer spectroscopy; Neel temperature; Phase transitions; Room temperature; Solid solutions; Synthesis; Synthesis and Properties of Inorganic Compounds
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023623601599

Mg-containing solid solutions based on Y 2 FeTaO 7 and formed by various mechanisms of heterovalent substitution were synthesized and had the following compositions: Y 2 Fe 0.55 Mg 0.3 Ta 1.15 O 7 , Y 2 Fe 0.625 Mg 0.3 Ta 1.075 O 7 , Y 2 Fe 0.7 Mg 0.3 TaO 7 , Y 2 Fe 0.7 Mg 0.2 Ta 1.1 O 7 , Y 2 Fe 0.85 Mg 0.15 TaO 7 , Y 1.85 Mg 0.15 Fe 0.925 Ta 1.075 O 7 , and Y 1.85 Mg 0.15 FeTaO 7 . It was shown that all synthesized solid solutions have a pyrochlore-like layered structure (space group P 3 1 21), in which Fe 3+ 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 Néel transition at the Néel 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 Mössbauer spectroscopy.