Structure and transport properties of the novel (Dy,Er,Gd,Ho,Y)3Fe5O12 and (Dy,Gd,Ho,Sm,Y)3Fe5O12 high entropy garnets

• Published in: Journal of the European Ceramic Society 2021-06, Vol.41 (6), p.3844-3849
• Main Authors: Dąbrowa, Juliusz, Cieślak, Jakub, Zajusz, Marek, Moździerz, Maciej, Berent, Katarzyna, Mikuła, Andrzej, Stępień, Anna, Świerczek, Konrad
• Format: Article
• Language: English
• Subjects: Ferrites; Garnets; High entropy oxides; Magnetic materials; Mossbauer effect
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2020.12.052

[Display omitted] •The iron-containing high-entropy garnets are synthesized for the first time.•(Dy,Er,Gd,Ho,Y)3Fe5O12 and (Dy,Gd,Ho,Sm,Y)3Fe5O12 exhibit excellent stability.•The electrical behavior differs significantly from the conventional garnets.•The Raman and Mossbauer spectra indicate distorted character of the lattice. High-entropy, iron-containing, garnet-structured oxides with (Dy,Er,Gd,Ho,Y)3Fe5O12 and (Dy,Gd,Ho,Sm,Y)3Fe5O12 compositions are synthesized for the first time. A modified Pechini method followed by calcination at 700 °C and sintering at 1300 °C enables obtaining single-phase, homogenous materials of cubic structure with Ia-3d symmetry. High-temperature in-situ X-ray diffraction studies show excellent phase stability of the garnets, as well as moderate thermal expansion coefficient, ca. 11·10−6 K-1 in 25−1000 °C temperature range. Raman spectroscopy measurements indicate the presence of local distortion of structural polyhedra, likely associated with the high-entropy effect. The collected Mossbauer spectra confirm distorted character of the lattice. Influenced by the presence of Fe3+ in locally distorted octahedra and tetrahedra, the electrical conduction at low temperatures of both oxides remains much lower comparing to Y3Fe5O12 (yttrium iron garnet - YIG), as well as to other rare-earth garnets up to 600 °C, where it reaches value similar to YIG.