A high-pressure study of Co-rich decagonal Al–Co–Ni and its approximant, the W phase

Abstract

The stability of Co-rich decagonal Al–Co–Ni and its closely related approximant phase, W-Al–Co–Ni, was studied in situ using powder diffraction and synchrotron radiation at high pressures up to 61.4(1) GPa (d-Al–Co–Ni) and 50.6(2) GPa (W-Al–Co–Ni), respectively. Within the experimental errors, both compounds show comparable values of the bulk modulus, i.e. K₀=120(11) GPa for the quasicrystal and K₀=138(11) GPa for its approximant phase, respectively. Both phases were found to be stable within the framework of the experiment. The results indicate that the local structure dominates the bulk property and the type of long-range order has only a minor influence.

Acknowledgements

Part of this work was performed at the Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland. Experimental assistance from the staff of the MS beamline is gratefully acknowledged. We thank the Swiss National Science Foundation for financial support under grant no. 200021-105233.