In situ study of icosahedral Zn-Mg-Dy and Co-rich decagonal Al-Co-Ni at high pressures and high temperatures

An in situ high-pressure high-temperature x-ray diffraction study on single-crystalline icosahedral Zn-Mg-Dy up to 12.5(4) GPa at 873 K and powdered Co-rich decagonal Al-Co-Ni up to 12.3(4) GPa at 973 K has been performed using a heatable diamond-anvil cell and synchrotron radiation. Quantitative reciprocal-space reconstruction from image plate data was used for evaluating the single-crystal data. The compressibility of the materials at ambient temperature was determined from x-ray powder diffraction up to 30.3(2) GPa for icosahedral Zn-Mg-Dy and 61.4(1) GPa for Co-rich decagonal Al-Co-Ni. The bulk modulus at zero pressure and its pressure derivative were determined from fitting third-order Birch-Murnaghan equations of state as K0 = 92(4) GPa, K' = 3.1(3) for icosahedral Zn-Mg-Dy and K0 = 120(11) GPa, K' = 7.1(7) for Co-rich decagonal Al-Co-Ni, respectively. The compressibilities of the quasicrystals are discussed with respect to their structure types and the available literature data. To a first approximation, a linear dependency of the squared electron density at the border of the Wigner-Seitz atomic cell from the ratio of the bulk modulus and the molar volume was found. This behaviour is comparable to that of periodic alloys