Two Different Mechanisms of Metal Cluster Formation in the Rhombohedral Spinel Structures: AlV2O4 and CuZr1.86(1)S4

Таланов, М. В.

doi:10.1021/acs.cgd.8b00151

Cited by 7 publications

(4 citation statements)

References 76 publications

(97 reference statements)

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“…The structural-descriptor-based approach has attracted much research attention in chemistry and materials science due to its potential applications in rapid estimation of phase stability and materials properties, with only a minimal calculation resource requirement compared to ab inito approaches. , Spinel-type compounds have aroused extensive research due to their prominent applications in electronics, optics, , catalysis, , magnetism, , batteries, , and environmental protection . With the general formula {A}(B) 2 [X] 4 , materials based on the spinel structure are able to accommodate a large variety of chemical elements, providing fascinating and diverse properties. − Therefore, developing the spinel-owned structural descriptor is urgent for materials design and discovery …”

Section: Introductionmentioning

confidence: 99%

Tolerance Factor and Phase Stability of the Normal Spinel Structure

Song

Liu

2020

Crystal Growth & Design

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Tolerance factor for the normal-spinel structure is introduced as a structural descriptor to predict the phase stability. It is derived following similar principles as those of perovskite and garnet structures, i.e., the geometrical relationship between multitype polyhedra. The calculation of tolerance factor only requires the ionic radii of compositional components involved. A survey of the tolerance factor over 120 AB2X4-type compounds proves the reliability. The numerical values are distributed below 1, which originates from the compressed octahedra which support the framework of spinel. The tolerance factor will be helpful in machine learning and high-throughput screening methods for fast evaluation of phase stability and materials properties of spinel-type compounds.

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Section: Introductionmentioning

confidence: 99%

Tolerance Factor and Phase Stability of the Normal Spinel Structure

Song

Liu

2020

Crystal Growth & Design

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“…In our previous works [21,23,24], we studied the structural mechanisms of the formation of "orbital molecules" in the crystals using crystal chemical and group-theoretical approaches and showed the involvement of different degrees of freedom (lattice, spins, orbitals, and charges) in the formation of these "molecules". The emergence of a complex multi-order state is expected in the rhombohedrally distorted spinels with the R3m space group [25,26]. In addition, it is important to note that the CuZr 2 O 4 compound is a structural analogue of CuTi 2 S 4 and crystallizes in the spinel type of structure [27].…”

Section: Introductionmentioning

confidence: 99%

Multi-order and structural mechanism of atom nanocluster formation in rhombohedral Cu-Zr-thiospinels

Talanov¹,

Talanov²

2022

Nanosystems: Phys. Chem. Math.

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A structural mechanism for the formation of nanoclusters and the rhombohedral modification of CuZr 1.86(1) S 4 has been proposed. Group-theoretical and crystal-chemical methods are used to study the features of the crystal structure and multi-order in Cu-Zr-thiospinel. A multi-order is a structural organization of a material, in the formation of which different degrees of freedom of a crystal participate. It has been proven that the rhombohedral structure of CuZr 1.86(1) S 4 is formed as a result of displacements and orderings of all types of atoms. It is theoretically shown that the formation of a rhombohedral phase is associated not only with the lattice, but also with the charge and, possibly, orbital degrees of freedom of the crystal. Theory predicts that the rhombohedral phase must be an improper ferroelastic. An important feature of the rhombohedral structure is metal nanoclusters: "bunch" of dimers, trimers, and tetrahedra. Bunch of dimers are an unusual type of self-organization of atoms in rhombohedral spinel-like structures, formed by atoms of two (tetrahedral and octahedral) frustrated crystal sublattices. KEYWORDS order parameter, multi-order, structural mechanism, rhombohedral modification, nanocluster ACKNOWLEDGEMENTS The reported study was funded by Russian Science Foundation (RSF) -research projects No. 22-22-00183, https://rscf.ru/project/22-22-00183/ FOR CITATION Talanov V.M., Talanov M.V. Multi-order and structural mechanism of atom nanocluster formation in rhombohedral Cu-Zr-thiospinels .

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“…Sometimes the formation of a low-symmetry phase occurs immediately upon synthesis (crystallization) of a substance without any real phase transitions. In this case, the relationship between the structures of the high-symmetry and the low-symmetry phases can be interpreted as a virtual phase transition . In our review, we exclusively consider this third group of structural transformations in the pyrochlore family.…”

Section: Introductionmentioning

confidence: 99%

Structural Diversity of Ordered Pyrochlores

Таланов

2021

Chem. Mater.

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Pyrochlores belong to a numerous family of crystalline materials with a rich variety of technologically important functional properties and developed structural diversity of possible transformations including isosymmetric, reconstructive, and phase transitions of second order (and first order close to second order). Here, using a combination of group-theoretical and crystallographic analysis, we report a uniform classification of 343 types of possible ordered phases, which are theoretically derived from only one initial A 2 B 2 X 6 Y pyrochlore structure by different specific physical mechanisms (order parameters or its combinations) and show a hierarchical relationship between them. A symmetry analysis of the intrinsic relationships between structural degrees of freedom and atomic order in pyrochlore crystals made it possible to highlight six nominal classes of atomic order depending on the ordered sublattice, and by taking into account the role of the improper ordered parameters, only four classes remain: X, XY, ABX, and ABXY. For each of these abstract classes of atomic order the modified Barnighausen tree, illustrating the symmetry pathways of group−subgroup relation and participation of relevant order parameters, was constructed. Three fundamental structural features of the ordered pyrochlores have been established: (a) the impossibility of "pure" (not accompanied by atomic displacements) cation ordering at the A and B pyrochlore sublattices (16d and 16c Wyckoff positions, respectively); (b) the impossibility of "pure" ordering of anions at the X sublattice (48f Wyckoff position); (c) atomic ordering in the A sublattice which is always accompanied by atomic ordering in the B sublattice. A brief review of experimentally known ordered pyrochlores consistent with our structural predictions is given. Finally, the main directions of the theoretical results application including interpretation of the phase transition origins, experimental property predictions, the choice of a model for structural refinement or for materials design as a starting point for energy calculations, and a classification of the hierarchical relationship between phases are discussed. This study provides a symmetry guide for the extensive family of ordered pyrochlores and shows the origin of its structural diversity.

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Two Different Mechanisms of Metal Cluster Formation in the Rhombohedral Spinel Structures: AlV₂O₄ and CuZr_1.86(1)S₄

Cited by 7 publications

References 76 publications

Tolerance Factor and Phase Stability of the Normal Spinel Structure

Tolerance Factor and Phase Stability of the Normal Spinel Structure

Multi-order and structural mechanism of atom nanocluster formation in rhombohedral Cu-Zr-thiospinels

Structural Diversity of Ordered Pyrochlores

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