Structure, composition and chemical order characterization of i-QCs and ACs
Research group: Cesar Pay Gómez.
Determining the atomic structure of QCs has been a major challenge due to the lack of 3D-periodicity and the presence of chemical disorder. The discovery of the binary QC i-Yb-Cd therefore represented an important milestone. Owing to the combination of well-defined chemical order, good X-ray contrast between constituent elements, and the existence of two different ACs in the Yb-Cd system a complete atomic structure characterization of an i-QC was achieved for the first time. Today, the structure model of i-Yb-Cd is at the heart of the large family of Tsai-type i-QCs.
In this project we build on this model in order to conclusively characterize atomic structure and chemical order of new representatives of RE i-QCs and ACs obtained from ambient and high pressure synthesis. For structure elucidation we will rely on single crystal (and powder) X-ray diffraction using in-house and synchrotron instrumentation. The use of synchrotron radiation will improve the signal to noise ratio and allow for high dynamic range data sets. The application of neutron diffraction may occasionally be useful to resolve contrast/absorption issues with X-rays. Composition analysis and chemical order characterization will also include selected area electron diffraction and SEM/TEM/microprobe analysis. The unambiguous atomic structure and chemical order characterization of samples is imperative prior to property measurements.