Low-temperature structural stability of Cd₆M (M  = Ho, Er, Tm and Lu) cubic crystalline approximants

Abstract

TEM observations and electrical resistivity measurements have been performed to investigate the low temperature stability, e.g. the occurrence of a phase transition, in Cd₆ M (M = Ho, Er, Tm and Lu) approximants, which have the smallest M atomic radii among a series of Cd₆ M compounds. Unlike other Cd₆ M compounds, no changes or anomalies were observed in selected-area electron diffraction patterns or in electrical resistivity down to 20 and 15 K, respectively. Therefore, we conclude that a phase transition does not occur in Cd₆ M (M = Ho, Er, Tm and Lu) and orientational ordering of the Cd₄ tetrahedron is kinetically suppressed when the space inside the icosahedral cluster is reduced to a certain level.

Keywords:

• quasicrystals
• phase transition
• icosahedral cluster
• electron diffraction

Acknowledgements

This work was supported by Grant-in-Aid (KAKENHI (20045017)) and was carried out via joint research at the Institute for Solid State Physics, University of Tokyo. The authors wish to thank M. Ichihara, D. Hamane and M. Koike of Materials Design and Characterization Laboratory, Institute for Solid State Physics, University of Tokyo, for their assistance during TEM operations.