The MAX phase borides Zr2SB and Hf2SB

Zr2SB and Hf2SB were synthesized via solid-state reactions and the crystal structures were determined by powder X-ray diffraction. Both compounds crystallize in the hexagonal Cr2AlC-type structure (P63/mmc; Z = 2; Zr2SB a = 3.5001(1) Å, c = 12.2712(2) Å; Hf2SB a = 3.4671(1) Å, c = 12.1046(2) Å). The...

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Vydané v:Solid state sciences Ročník 106; s. 106316
Hlavní autori: Rackl, Tobias, Johrendt, Dirk
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: Elsevier Masson SAS 01.08.2020
Predmet:
Borides
DFT calculations
Elastic properties
MAX phases
Structural properties
MAX phases
Borides
Elastic properties
Structural properties
DFT calculations
ISSN:1293-2558, 1873-3085
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Popis
Shrnutí:Zr2SB and Hf2SB were synthesized via solid-state reactions and the crystal structures were determined by powder X-ray diffraction. Both compounds crystallize in the hexagonal Cr2AlC-type structure (P63/mmc; Z = 2; Zr2SB a = 3.5001(1) Å, c = 12.2712(2) Å; Hf2SB a = 3.4671(1) Å, c = 12.1046(2) Å). The lattice parameters and bond lengths are slightly longer and the M6X octahedra are less distorted compared to the known carbides. Resistivity and magnetic measurements reveal that Zr2SB and Hf2SB are good metallic conductors and Pauli paramagnets. Ab-initio DFT calculations of the electronic structure confirm the nonmagnetic metallic state and show mainly ionic bonds, which are weaker than in the carbides. The elastic constants indicate that Zr2SB and Hf2SB are brittle and exhibit a less two-dimensional character compared to other MAX phases. [Display omitted] •The new MAX phase borides Zr2SB and Hf2SB have been discovered and characterized.•DFT calculations confirm the nonmagnetic metallic state and reveal mainly ionic bonds.•The bulk moduli are slightly smaller than in the carbides due to weaker Zr,Hf–B bonding.
ISSN:1293-2558
1873-3085
DOI:10.1016/j.solidstatesciences.2020.106316