REPtX compounds with structures related to AIB<sub>2</sub>- and MgAgAs-type (RE=Y, Rare earth element;Χ = Ρ, As, Sb)

Wenski, G.; Mewis, A.

doi:10.1524/zkri.1986.176.12.125

Cited by 10 publications

(8 citation statements)

References 7 publications

(11 reference statements)

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“…Along these lines, it is interesting to note that in LaPtSb, the buckling is largely manifested in out-of-plane shifts of the Pt atoms, minimizing La-Sb collisions, while in LaAuGe the smaller Ge atoms show greater displacement. These results also correlate with observations described in the literature for other AlB 2 -type variants [38][39][40], where the degree of buckling in the crystal structures are often attributed to the size of the stuffing cation A. As the radius of the stuffing cation increases, c in-creases and interactions between the layers are reduced.…”

Section: Resultssupporting

confidence: 90%

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

Lim

Zhang

et al. 2019

APL Materials

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Polar metals are an intriguing class of materials that simultaneously host free carriers and polar structural distortions. Despite the name "polar metal," however, most well-studied polar metals are poor electrical conductors. Here, we demonstrate the molecular beam epitaxial (MBE) growth of LaPtSb and LaAuGe, two polar metal compounds whose electrical resistivity is an order of magnitude lower than the well studied oxide polar metals. These materials belong to a broad family of ABC intermetallics adopting the stuffed wurtzite structure, also known as hexagonal Heusler compounds. Scanning transmission electron microscopy (STEM) reveals a polar structure with unidirectionally buckled BC (PtSb, AuGe) planes. Magnetotransport measurements demonstrate good metallic behavior with low residual resistivity (ρLaAuGe = 59.05 µΩ·cm and ρ LaAP tSb = 27.81 µΩ·cm at 2K) and high carrier density (n h ∼ 10 21 cm −3 ). Photoemission spectroscopy measurements confirm the band metallicity and are in quantitative agreement with density functional theory (DFT) calculations. Through DFT-Chemical Pressure and Crystal Orbital Hamilton Population analyses, the atomic packing factor is found to support the polar buckling of the structure, though the degree of direct interlayer B − C bonding is limited by repulsion at the A − C contacts. When combined with insulating hexagonal Heuslers, these materials provide a new platform for fully epitaxial, multiferroic heterostructures. arXiv:1910.07685v1 [cond-mat.mtrl-sci]

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Section: Resultssupporting

confidence: 90%

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

Lim

Zhang

et al. 2019

APL Materials

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“…The first structure refinement for a pronounced two-dimensional polyanion was made for NdPtSb by Wenski and Mewis [48]. We therefore list both the NdPtSb and the LiGaGe type in Fig.…”

Section: Isopointal Ligage and Ndptsbmentioning

confidence: 99%

“…4) A doubling of the BaSn 5 unit cell upon a klassengleiche transition of index 2 (k2) results in the structure of YPtAs [48] (Fig. 4).…”

Section: Basn 5 and Yptasmentioning

confidence: 99%

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AlB₂-related intermetallic compounds – a comprehensive view based on group-subgroup relations

Hoffmann¹,

Pöttgen²

2001

Zeitschrift Für Kristallographie - Crystalline Materials

286

110

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46 structure types of binary and ternary intermetallic compounds have been derived from the well known, simple aristotype AlB 2 . Many compounds with the general compositions RX 2 , RT 2 , RTX, and R 2 TX 3 (R ¼ alkaline earth, rare earth or actinoid metal; T ¼ transition metal; X ¼ main group element) belong to this family. The structural similarities between these compounds are manifested by an ordering of the transition metal atoms and main group element atoms on the boron positions of the AlB 2 type. Also an ordering of vacancies on the boron positions occurs in some compounds. Striking structural motifs of the RX 2 , RT 2 , RTX, and R 2 TX 3 compounds are planar or puckered six-membered rings consisting of X 6 , T 6 , T 3 X 3 , and T 2 X 4 separated by the respective R atoms. The crystal chemical relationships between these compounds are discussed on the basis of a group-subgroup scheme in the concise and compact Bärnighausen formalism with respect to the aristotype AlB 2 . Two different branches of AlB 2 related structures are discussed. In the first, the hexagonal/trigonal branch, six-membered rings carry at least a three-fold axis, while in the orthorhombic/ monoclinic branch the distortions are more pronounced. The pseudo-hexagons show significant tilting and a loss of hexagonal/trigonal symmetry. Significant variations of the chemical bonding occur for some structure types, and therefore they may only be considered to be isopointal rather than isotypic. These "isopointal conversions" are based on a gradual changeover from two-to three-dimensionally infinite polyanions. Besides the group theoretical group-subgroup scheme we also discuss chemical bonding in these AlB 2 related intermetallic compounds.

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“…YbPtP type structure 44 . The tantalum-rich BeBTa2 is a layered orthorhombic structure, like CeNiC2 45 .…”

Section: 1structural Propertiesmentioning

confidence: 99%

Prediction of the fundamental properties of novel Be-B-Ta-based ternary compounds from first-principles calculations

Haque

Stampfl

2019

Phys. Rev. Materials

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Be-B/B-Ta based compounds are very attractive to researchers because of their high density and ultra-hardness. But ternary Be-B-Ta compounds are neither synthesized nor predicted. In this paper, variable composition evolutionary crystal structure prediction calculations based on firstprinciples method have been performed to find the stable crystal structure containing Be-B-Ta at ambient condition. The predicted five compounds BeB2Ta, BeB3Ta2 (high-pressure phase), BeBTa, BeBTa2, and Be2B2Ta have been found to be highly dense and very hard materials. All these compounds are metallic and spin-orbit coupling (SOC) effect is significant in them. Only two of them (BeB2Ta and Be2B2Ta) have been found to be superconductors within Migdal-Eliashberg theory. The calculated critical temperature including SOC effect is 8 and 9 K for BeB2Ta and Be2B2Ta, respectively. Because of their energetic and dynamic stability, these compounds might be favorable to synthesize in the laboratory. IntroductionBeryllium (Be) and boron (B) are light elements with different electronic structures, first one is the metal and the second one is the semiconductor, while tantalum is the electron-rich transition metal. Beryllium has applications in X-ray equipment 1 , as effective moderators and reflectors for neutrons 2 , aircraft, rockets, etc. 3,4 . The use of a glove box is very effective way to synthesize industrially beryllium-containing compounds 5 . Different phases are possible by the combination of Be and B, such as Be2B 6 , Be4B 7 , and boron-rich compounds BeB2 8-12 and BeB4 (high-pressure phase) 10 . Usually, covalent-bond forming element based compounds show high hardness, for example, BeB2 (Cmcm) 9 , diamond 13 , c-BN 14 , and BC2N 15 . The diamond, c-BN, and BC2N would be synthesized at high pressure and high-temperature condition 16 . On the other way, light element combined with electron-rich transition metal-based materials show also high hardness 17-21 , such as ReB2 22 , IrN2 23 , RuO2 24 , WB4 25 , MnB4 and CrB4 26 . This method is very effective to design superhard materials. The different phases of tantalum borides (TaB, TaB2, Ta3B4) have been synthesized at ambient pressure 27 . It has been found that TaB and TaB2 have high hardness (~30 GPa) 27-29 . The theoretically calculated Vickers hardness of TaB is 28.6 GPa 30 . Thus, transition metal rich borides show good mechanical behavior for practical applications.Boron-rich BeB2 and MgB2 shows superconductivity, although the first one has very low transition temperature (0.72 K) 8 , the second one has the highest transition temperature (39 K) among simple binary structure 31 . In MgB2, σ-band electrons strongly bonded with in-plane phonons to induce a high superconducting transition temperature. Boron-rich transition metal boride TaB2 might show superconductivity with a critical temperature of 9.5 K 32,33 , although others reported the absence of superconductivity 34,35 . The strong hybridization between Ta 5d and B 2p orbitals outside the hexagonal basis plane might be responsi...

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REPtX compounds with structures related to AIB₂- and MgAgAs-type (RE=Y, Rare earth element;Χ = Ρ, As, Sb)

Cited by 10 publications

References 7 publications

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

AlB₂-related intermetallic compounds – a comprehensive view based on group-subgroup relations

Prediction of the fundamental properties of novel Be-B-Ta-based ternary compounds from first-principles calculations

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REPtX compounds with structures related to AIB2- and MgAgAs-type (RE=Y, Rare earth element;Χ = Ρ, As, Sb)

Cited by 10 publications

References 7 publications

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

High electrical conductivity in the epitaxial polar metals LaAuGe and LaPtSb

AlB2-related intermetallic compounds – a comprehensive view based on group-subgroup relations

Prediction of the fundamental properties of novel Be-B-Ta-based ternary compounds from first-principles calculations

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Product

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REPtX compounds with structures related to AIB₂- and MgAgAs-type (RE=Y, Rare earth element;Χ = Ρ, As, Sb)

AlB₂-related intermetallic compounds – a comprehensive view based on group-subgroup relations