Low-temperature structural phase transition in a Cd6Y 1/1 approximant

R. Tamura, K. Edagawa, C. Aoki, S. Takeuchi, and K. Suzuki
Phys. Rev. B 68, 174105 – Published 13 November 2003
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Abstract

Electron and x-ray-diffraction studies have revealed that a Cd6Y 1/1 crystalline approximant (Im3¯, a=1.5482nm) undergoes a phase transition at some temperature around 160 K. The transition accompanies a change of the lattice period as well as an extremely small tetragonal distortion (c/a=0.9992±0.0002). Differential scanning calorimetry experiment also exhibits an anomaly around 175 K and the transition entropy suggests that the transition is of the order-disorder type with respect to the orientation of the Cd tetrahedron situated inside the icosahedral cluster. The phenomenon is discussed within the formalism of the Landau theory and it is suggested that the transition is attributed to an irreducible representation at the zone-boundary (N point) and the low-temperature phase possesses an orthorhombic 2a×2a×a superlattice.

  • Received 29 May 2003

DOI:https://doi.org/10.1103/PhysRevB.68.174105

©2003 American Physical Society

Authors & Affiliations

R. Tamura1, K. Edagawa2, C. Aoki1, S. Takeuchi1, and K. Suzuki2

  • 1Department of Materials Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan
  • 2Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan

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Vol. 68, Iss. 17 — 1 November 2003

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