Investigation of intermetallic phase diagrams, synthesis and crystal growth of i-QCs and ACs at ambient pressure

Research group: Cesar Pay Gómez.

Ternary systems, like RE-TM-Tt (RE=Lanthanides, TM=d-block elements,Tt = p-block elements), will be systematically investigated for new i-QCs and ACs. These systems can be exploited for studying thermodynamic relations and phase stability through melt-growth of single crystals. The compositional and temperature windows of formation of new phases can be screened by thermal analysis (DTA and DSC) and high temperature powder XRD experiments and the identified formation conditions subsequently utilized for targeted melt-growth of (quasi) crystalline samples and their isolation by melt-centrifugation. The thermodynamic stability of isolated products will be examined by thermal analysis and HT-PXRD.

The goal of this project line is to increase the number of RE-containing i-QCs and ACs through systematic phase diagram analysis. Within this project line falls also the synthesis of known RE i-QCs (i.e. i-RE-Cd) and ACs for investigating pressure-induced phase and property changes.

Research group: Ulrich Häussermann.

The recent discovery of an i-Al-Cu-Fe phase with an unusual composition in a meteorite fragment fueled our hypothesis that high pressure synthesis can be a novel route to stabilize i-QCs with new compositions and to explore phase relations between Bergman and Tsai i-QC families. We will perform exploratory investigations of binary and ternary systems using large volume multi-anvil high pressure equipment and cell assemblies allowing for melt-growth of (quasi) crystalline samples at pressures up to 15 GPa. Crystalline specimens will be isolated by melt-centrifugation of the recovered sample at ambient pressure.

The goal of this project line is the confirmation of the hypothesis that novel i-QCs will be accessible through high pressure synthesis and the subsequent identification and optimization of formation and crystal growth conditions for RE-containing i-QCs and ACs at high pressures. In situ diffraction studies at synchrotron facilities (such as the ESRF, Grenoble) are expected to be useful for rapid mapping of formation conditions of (quasi) crystalline samples.