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

[Display omitted] • The iron-containing high-entropy garnets are synthesized for the first time. • (Dy,Er,Gd,Ho,Y) 3 Fe 5 O 12 and (Dy,Gd,Ho,Sm,Y) 3 Fe 5 O 12 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) 3 Fe 5 O 12 and (Dy,Gd,Ho,Sm,Y) 3 Fe 5 O 12 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- 3 d 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 Y 3 Fe 5 O 12 (yttrium iron garnet - YIG), as well as to other rare-earth garnets up to 600 °C, where it reaches value similar to YIG. [ABSTRACT FROM AUTHOR]