In this paper, we present a comprehensive analysis of the atomic and electronic structure of the icosahedral quasicrystalline powder Al65Cu23Fe12 (QC) using both experimental and theoretical methods. The study of the QC powder i-Al65Cu23Fe12 was carried out using X-ray diffractometry, scanning electron microscopy, Mössbauer spectroscopy, as well as X-ray absorption spectroscopy (XANES and EXAFS) and X-ray photoelectron spectroscopy. It was found that the surface layer of the i-Al65Cu23Fe12 quasicrystal consists of Al2O3 and Cu2O oxides, while the internal structure is characterized by the presence of the icosahedral phase Al65Cu23Fe12 and the cubic phase β-Al(Cu0.5Fe0.5). The developed theoretical model of the i-Al65Cu23Fe12 QC structure based on the transformation of the crystalline analogue Al7Cu2Fe demonstrates good agreement with the experimental data on the structure obtained by EXAFS and XANES methods. The electronic structure of the upper part of the valence band and the lower part of the conduction band of i-Al65Cu23Fe12 QC was analyzed using X-ray photoelectron spectroscopy, XANES analysis and first-principles calculations.
Quasicrystals, which occupy an intermediate position between crystalline and amorphous solids, attract considerable attention due to their unique physical properties due to their aperiodic atomic structure. Of particular interest is the study of the local atomic and electronic structure of quasicrystalline alloys, since it determines their macroscopic characteristics. This paper presents the results of a study of the local atomic and electronic structure of the quasicrystalline powder i-Al65Cu23Fe12 obtained by rapid melt solidification.
The formation of a single-phase icosahedral quasicrystal was confirmed by X-ray diffraction and transmission electron microscopy. The X-ray absorption spectra (XAS) at the edges of Al K, Cu K, and Fe K were measured to study the local atomic environment of each element. Analysis of the XANES spectra revealed significant differences in the local symmetry around the Al, Cu, and Fe atoms.
EXAFS (extended X-ray absorption fine structure) data were used to determine the interatomic distances and coordination numbers. It was found that Al atoms tend to form shorter bonds than Cu and Fe atoms. The calculation of the electronic structure by the DFT method showed the presence of a pseudogap near the Fermi level, which is consistent with the dielectric properties of quasicrystals. The results indicate a complex local atomic and electronic structure of the quasicrystalline powder i-Al65Cu23Fe12, which determines its unique properties.
Author: IE Uflyand, EG Drogan, VE Burlakova, KA Kydralieva, IN Shershneva, GI Dzhardimalieva
Institute:
Center for Intelligent Materials Research, Southern Federal University, 5 Sorge St., Rostov-on-Don, 344090, Russia
Research Institute of Physics, Southern Federal University, Stachki Ave., 194, Rostov-on-Don, 344090, Russia
Don State Technical University, Gagarin Square, 1, Rostov-on-Don, 344002, Russia