Related Experiment Video
Updated: Nov 8, 2025
Author Spotlight: Accelerating Discovery in Microporous Material Chemistry
Published on: October 6, 2023
In-plane ordered quaternaryM4/3'M2/3″AlB2phases (i-MAB): electronic structure and mechanical properties from
Hans Lind1, Martin Dahlqvist1, Johanna Rosen1
1Thin Films Physics, Department of Physics, Chemistry, and Biology, Linköping University, SE-581-83 Linköping, Sweden.
Abstract:
We have by means of first principles density functional theory calculations studied the mechanical and electronic properties of the so calledi-MAB phases,M4/3'M″2/3AlB2, whereM' = Cr, Mo, W andM″ = Sc, Y. These phases, experimentally verified for Mo4/3Sc2/3AlB2and Mo4/3Y2/3AlB2, display an atomically laminated structure with in-plane chemical order between theM' andM″ elements. Structural properties, along with elastic constants and moduli, are predicted for different structural symmetries, including the reportedR3̄m(#166) space group. We find all consideredi-MAB phases to be metallic with a significant peak in the electronic structure at the Fermi level and no significant anisotropy in the electronic band structure. The simulations also indicate that they are rather hard and stiff, in particular the Cr-based ones, with a Young's modulusEof 325 GPa forM″ = Sc. The Mo-based phases are similar, withE= 299 GPa forM″ = Sc, which is higher than the corresponding laminated carbides (i-MAX phases).
More Related Videos
Related Concept Videos
02:37Metallic Solids
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
02:42Valence Bond Theory
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:46Electron Configurations
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p,...
02:28Electronic Structure of Atoms
An atom comprises protons and neutrons, which are contained inside the dense, central core called the nucleus, with electrons present around the nucleus. Taking into account the wave–particle duality of electrons and the uncertainty in position around the nucleus, quantum mechanics provides a more accurate model for the atomic structure. It describes atomic orbitals as the regions around the nucleus where electrons of discrete energy exist, characterized by four quantum...
02:42Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...