High-Temperature Layered Modification of Mn<sub>2</sub>In<sub>2</sub>Se<sub>5</sub>

Layered chalcogenides are interesting from the point of view of the formation of two-dimensional magnetic systems for relevant applications in spintronics. High-spin Mn<sup>2+</sup> or Fe<sup>3+</sup> cations with five unpaired electrons are promising in the search for compou...

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Main Authors: Ivan V. Chernoukhov, Anton D. Pyreu, Andrey N. Azarevich, Alexander N. Samarin, Alexey V. Bogach, Konstantin O. Znamenkov, Andrei V. Shevelkov, Valeriy Yu. Verchenko
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/9/1904
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Summary:Layered chalcogenides are interesting from the point of view of the formation of two-dimensional magnetic systems for relevant applications in spintronics. High-spin Mn<sup>2+</sup> or Fe<sup>3+</sup> cations with five unpaired electrons are promising in the search for compounds with interesting magnetic properties. In this study, a new layered modification of the Mn<sub>2</sub>In<sub>2</sub>Se<sub>5</sub> compound from the A<sub>2</sub>B<sub>2</sub>X<sub>5</sub> family (“225”) was synthesized and investigated. A phase transition to the polymorph with primitive trigonal lattice was recorded at a temperature of 711 °C, which was confirmed by simultaneous thermal analysis, X-ray powder diffraction at elevated temperatures, and sample annealing and quenching. The stability of Mn<sub>2</sub>In<sub>2</sub>Se<sub>5</sub> in air at high temperatures was investigated by thermal gravimetric analysis and powder X-ray diffraction. The new polymorph of Mn<sub>2</sub>In<sub>2</sub>Se<sub>5</sub> crystallizes in the Mg<sub>2</sub>Al<sub>2</sub>Se<sub>5</sub> structure type, as revealed by the Rietveld refinement against powder X-ray diffraction data. The crystal structure can be viewed as a close-packing of Se anions, in which indium and manganese cations are enclosed inside tetrahedral and octahedral voids, respectively, according to the <i>A</i><sub>Mn</sub><i>B</i><sub>In</sub><i>CB</i><sub>In</sub><i>C</i><sub>Mn</sub><i>A</i>… sequence. Magnetization measurements reveal an antiferromagnetic-like transition at a temperature of 6.3 K. The same magnetic properties are reported in the literature for the low-temperature R-centered trigonal polymorph. An approximation by the modified Curie–Weiss law yields a significant ratio of |<i>θ</i>|/<i>T</i><sub>N</sub> = 28, which indicates strong magnetic frustration.
ISSN:1420-3049