Formation of scandium carbides and scandium oxycarbide from the elements at high-(P, T) conditions
Synchrotron diffraction experiments with in situ laser heated diamond anvil cells and multi-anvil press synthesis experiments have been performed in order to investigate the reaction of scandium and carbon from the elements at high-(P,T) conditions. It is shown that the reaction is very sensitive to the presence of oxygen. In an oxygen-rich environment the most stable phase is ScO{sub x}C{sub y}, where for these experiments x=0.39 and y=0.50-0.56. If only a small oxygen contamination is present, we have observed the formation of Sc{sub 3}C{sub 4}, Sc{sub 4}C{sub 3} and a new orthorhombic ScC{sub x} phase. All the phases formed at high pressures and temperatures are quenchable. Experimentally determined elastic properties of the scandium carbides are compared to values obtained by density functional theory based calculations. - Graphical Abstract Legend (TOC Figure): Table of Contents Figure Selected images recorded with a MAR345 image plate detector show the reaction of alpha-Sc and graphite at high-(P,T) conditions. Left: mixture of alpha-Sc and graphite. Right: recovered sample after laser heated the diamond anvil cell.