Quasicrystals, which have long-range order but no translational symmetry, represent a unique class of materials with interesting physical properties. Studying their behavior under high pressure opens up new perspectives for understanding structural stability and possible phase transitions. In this paper, a comparative analysis of the icosahedral phases of Ti–Zr–Ni and Al–Cu–Fe under high pressure is performed.
Compression experiments were performed using high-pressure diamond anvil cells. Structural changes were monitored using X-ray diffraction. For both systems, it was found that the icosahedral phase retains its structure up to certain pressure values, after which phase transitions are observed.
Icosahedral phases (i-phases) of TiZrNi and AlCuFe alloys consisting of a single phase were synthesized by single-roll melting under inert argon. Using real-time synchrotron radiation (SR) energy dispersive diffraction and a high-pressure diamond anvil cell, the compressive strength of i-TiZrNi and i-AlCuFe was studied under high pressure (up to 25 GPa). In contrast to i-AlCuFe, i-TiZrNi exhibited repetitive deviations from the Birch-Murnaghan equation of state, manifested as hysteresis loops during the initial compression cycles. This work reports for the first time such a behavior of a quasi-crystalline material under hydrostatic pressure. Plastic deformation processes and effects associated with the small grain size of rapidly quenched TiZrNi alloys are considered as potential explanations. For Ti–Zr–Ni, the icosahedral phase exhibits greater resistance to pressure compared to Al–Cu–Fe. This may be due to differences in the atomic radii of the components and the type of chemical bond. In Al–Cu–Fe, a transition to the crystalline phase is observed at lower pressures, indicating a lower stability of the icosahedral structure.
The obtained results allow us to better understand the factors determining the stability of quasicrystals. In particular, the role of atomic radii and chemical bonding in the stability of the icosahedral structure. Further studies, including molecular dynamics simulations, may provide a more detailed picture of the atomic mechanisms underlying the observed phase transitions.
Author: U Ponkratz, R Nicula, A Jianu, E Burkel
Institute: FB Physics, LS Physics of New Materials, University of Rostock, August-Bebel-Strasse 55, D-18051 Rostock, Germany, National Institute of Materials Physics, P.O. Box MG-7, RO-76900 Bucharest-Magurele, Romania