Structural stability of an icosahedral Cd-Yb quasicrystal and its crystalline approximant under high pressure

Watanuki, Tetsu; Sato, Taku*; Tsai, A. P.*

Synchrotron X-ray powder diffraction studies on an icosahedral Cd-Yb quasicrystal (iCd-Yb), its crystalline approximant of CdYb (cCd-Yb) and the related CdEu (cCd-Eu) material were performed under pressures of up to about 40 GPa at room temperature. The icosahedral lattice of the atomic cluster in iCd-Yb and the bcc lattices in cCd-Yb and cCd-Eu were found to be stable under pressure. Although the Tsai-type atomic cluster can possibly be distorted in various ways, low-symmetry distortion modes do not seem to develop even at high pressure. It is considered that the cluster structure of centrosymmetric dense atomic packing prevented low-symmetry distortions and consequently provided the cluster lattice stability.