Monika Kušter (Author), Anton Meden (Author), Boštjan Markoli (Author), Zoran Samardžija (Author), Maja Vončina (Author), Pascal Boulet (Author), Émilie Gaudry (Author), Jean-Marie Dubois (Author), Sašo Šturm (Author)

Abstract

This study focused on the crystal and electronic structures of a newly discovered phase in the Al-Cr-Sc system. The latter two species do not mix in a binary alloy, but can be alloyed with aluminium in the vicinity of the Al$_{2−x}$Cr$_x$Sc composition, where 0.3 < x < 0.5. After preparation of the pure constituents via arc melting, high-temperature annealing at 990 °C for 240 h was required to achieve full mixing of the elements. A detailed characterisation of the crystal structure, alloy microstructure and stability was obtained using single-crystal X-ray diffraction (SCXRD) and powder X-ray diffraction (PXRD), in addition to transmission electron microscopy (TEM), especially in highangle annular dark-field scanning transmission electron microscopy (HAADF-STEM) mode, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDXS) and differential scanning calorimetry (DSC) measurements. The crystal structure was refined to a hexagonal unit cell of the MgZn$_2$ type, space group no. 194, P6$_3$/mmc, which belongs to the Laves phases family. Special attention was paid to the occupancy of the crystallographic sites that were filled by both Cr and Al atoms. First-principles calculations based on the density functional theory (DFT) were performed to investigate the electronic structure of this ternary phase. The total density of states (DOS) exhibited a pronounced sp character, where a shallow pseudo-gap was visible 0.5 eV below the Fermi energy that brought a small but definite contribution to the thermodynamic stability of the compound.

Keywords

Al-Cr-Sc system;Laves phase;crystal structure refinement;HAADF-STEM;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL NTF - Faculty of Natural Sciences and Engineering
UDC: 669
COBISS: 88540675 Link will open in a new window
ISSN: 2073-4352
Views: 98
Downloads: 45
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Other data

Type (COBISS): Article
Pages: 1535-1-1535-18
Volume: ǂVol. ǂ11
Issue: ǂiss. ǂ12
Chronology: 2021
DOI: 10.3390/cryst11121535
ID: 15297835