Development of a single-crystal X-ray diffraction system for hydrostatic-pressure and low-temperature structural measurement and its application to the phase study of quasicrystals

Abstract

We constructed a single-crystal synchrotron X-ray diffraction system to precisely study the structure under hydrostatic pressure conditions at low temperatures and applied it to a study on the phase transition phenomena of a Cd–Yb periodic approximant and a Cd–Yb quasicrystal. Four phases were newly observed for the 1/1 approximant crystal in a P–T range up to 5.2 GPa and down to 10 K. The innermost part of the atomic clusters of Cd₄ tetrahedra exhibited various orientational ordering sensitively depending on pressure and temperature. High pressure diffraction measurements using a highly parallel synchrotron X-ray beam and a hydrostatically compressed single crystal enabled us to detect the weak diffractions due to the subtle structural changes.

Acknowledgements

We thank Dr N. Hamaya for the fruitful discussion about the system design and T. Shobu for his technical support. This work is partially supported by a Grant-in-aid for Scientific Research (14740218, 17740238) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.