High-entropy oxide phases with magnetoplumbite structure

Винник, Д.А.; Trofimov, Evgeny; Живулин, В.Е.; Зайцева, О.В.; Gudkova, S.A.; Starikov, A.Yu.; Жеребцов, Д. А.; Kirsanova, A. A.; Häßner, Manuel; Niewa, Rainer

doi:10.1016/j.ceramint.2019.03.221

Cited by 74 publications

(21 citation statements)

References 55 publications

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“…Recently the high-entropy concept has been extended to metal diborides 17 carbides 18 nitrides, 19 and oxides. 20 The field of high-entropy oxides attracts attention as a current research topic, [21][22][23][24][25][26] particularly due to the functional properties that have been reported, such as high dielectric constant, 27 lithium superionic conductivity, 28 magnetic properties, [29][30][31] electrical and thermal conductivities, 32,33 reversible energy storage, 34 and high catalytic activity in CO oxidation. 35 Launching the field of high-entropy oxides, Rost 20 reported a single rocksalt structure for (Mg ,Ni, Co, Cu, Zn)O pellets produced using solid-state synthesis.…”

Section: Introductionmentioning

confidence: 99%

Solid‐state synthesis of multicomponent equiatomic rare‐earth oxides

et al. 2020

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Phase formation in multicomponent rare-earth oxides is determined by a combination of composition, sintering atmosphere, and cooling rate. Polycrystalline ceramics comprising various combinations of Ce, Gd, La, Nd, Pr, Sm, and Y oxides in equiatomic proportions were synthesized using solid-state sintering. The effects of composition, sintering atmosphere, and cooling rate on phase formation were investigated. Single cubic or monoclinic structures were obtained with a slow cooling of 3.3°C/min, confirming that rare-earth oxides follow a different structure stabilization process than transition metal high-entropy oxides. In an oxidizing atmosphere, both Ce and Pr induce a cubic structure, while only Ce plays that role in an inert or reducing atmosphere. Samples without Ce or Pr develop a single monoclinic structure. The structures formed at initial synthesis may be converted to a different one, when the ceramics are annealed in an additional atmosphere. Phase evolution of a five-cation composition was also studied as a function of sintering temperature. The binary oxides used as raw materials completely dissolve into a single cubic structure at 1450°C in air. K E Y W O R D S phase transformations, rare earths, reaction sintering How to cite this article: Pianassola M, Loveday M, McMurray JW, Koschan M, Melcher CL, Zhuravleva M. Solid-state synthesis of multicomponent equiatomic rare-earth oxides. J Am Ceram Soc.

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Section: Introductionmentioning

confidence: 99%

Solid‐state synthesis of multicomponent equiatomic rare‐earth oxides

et al. 2020

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“…In addition to two major classes high-entropy UHTCs (discussed above) that have been extensively studied in the last a few years, high-entropy nitrides [67], silicides [44,45], sulfides [98], fluorides [99], aluminides [43], hexaborides [100], carbonitrides [101], and aluminosilicides [38] have been fabricated. In the broader families of oxide-related HECs, the fabrication of high-entropy magnetoplumbites [87,102], zeolitic imidazolate frameworks [103], ferrites [104], phosphates [18,105], monosilicates [19,20], disilicates [106], and metal oxide nanotube arrays [107] have been reported. Medium-and high-entropy Compositionally Complex thermoelectrics have also been explored [40][41][42].…”

Section: Graphical Abstractmentioning

confidence: 99%

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

2020

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High-entropy ceramics (HECs) have quickly gained attention since 2015. To date, nearly all work has focused on five-component, equimolar compositions. This perspective article briefly reviews different families of HECs and selected properties. Following a couple of our most recent studies, we propose a step forward to expand HECs to Compositionally Complex ceramics (CCCs) to include medium-entropy and non-equimolar compositions. Using defective fluorite and ordered pyrochlore oxides as two primary examples, we further consider the complexities of aliovalent cations and anion vacancies as well as ordered structures with two cation sublattices.Better thermally-insulating yet stiff CCCs have been found in non-equimolar compositions with optimal amounts of oxygen vacancies and in ordered pyrochlores with substantial size disorder.It is demonstrated that medium-entropy ceramics (MECs) can prevail over their high-entropy counterparts. The diversifying classes of CCCs provide even more possibilities than HECs to tailor the composition, defects, disorder/order, and, consequently, various properties.

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“…Obviously, Li + ions can be easily incorporated into and extracted from the strongly disordered rock salt structure, which is supported by the very high ionic conductivity of up to 1 mS/cm for (Mg,Co,Ni,Cu,Zn) 0.67 Li 0.33 O. [8] Apart from further studies on materials with rock salt structure, [9] high-entropy oxides with spinel, [10] fluorite, [11] bixbyite, [12] perovskite [13] and magnetoplumbite structure [14] have been created and investigated. Further examples of high-entropy oxides can be found elsewhere.…”

Section: Introductionmentioning

confidence: 99%

“…To our knowledge, the high-entropy oxides investigated so far have been based on multiple elements on cationic sites with equal fractions of the cations involved in order to maximize the entropy. [4][5][6][7][8][9][10][11][12][13][14][15] On the one hand, this approach can also be applied to NaSICON materials, because a large variety of cations can be incorporated. [18] On the other hand, however, this class of materials also offers the opportunity to induce high disorder in the polyanionic lattice in terms of variable site occupancy with many different central tetrahedral ions, which is not possible for the oxides mentioned above.…”

Section: Introductionmentioning

confidence: 99%

Polyanionic Lattice Modifications Leading to High‐Entropy Sodium Ion Conductors: Mathematical Solution of Accessible Compositions

Tietz

Fronia²

2020

ChemPhysChem

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Sodium zirconium double phosphate NaZr2(PO4)3 can be used as a starting point for investigations of high‐entropy materials. Apart from the frequently used approach of partial substitution with four or more different transition metal cations, this class of materials also allows multiple substitutions of the phosphate groups. Herein modifications of the polyanionic lattice are considered and high‐entropy compositions are numerically determined with up to eight elements on the central tetrahedral lattice site of the so‐called NaSICON structure. For this study, the chemical formula was fixed as Na3Zr2(EO4)3 with E=B, Al, Si, P, As, Sb, S, Se and Te. The number of compositions increases exponentially with the increasing number of elements involved and with decreasing equal step size for each element. The maximum number of 237258 compositions is found for Na3Zr2([B,Al,Si,P,As,Sb,S,Se]O4)3 with a step size of 0.1 mol/formula unit. Of this compositional landscape, 143744 compositions fulfil the definitions of high‐entropy materials. The highest entropy factor of ΔSconfig/R=‐2.0405 is attributed to the compositions Na3Zr2(B0.5Al0.6Si0.4P0.3As0.3Sb0.3S0.3Se0.3)O12 and Na3Zr2(B0.6Al0.5Si0.4P0.3As0.3Sb0.3S0.3Se0.3)O12.

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High-entropy oxide phases with magnetoplumbite structure

Cited by 74 publications

References 55 publications

Solid‐state synthesis of multicomponent equiatomic rare‐earth oxides

Solid‐state synthesis of multicomponent equiatomic rare‐earth oxides

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

Polyanionic Lattice Modifications Leading to High‐Entropy Sodium Ion Conductors: Mathematical Solution of Accessible Compositions

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