New Epitaxially Stabilized Silicide Phases

A new epitaxial CoSi2 phase has been synthesized on Si(111) by molecular beam epitaxy (MBE) at room temperature (RT). Structural investigations revealed, that films grown onto an ultrathin CoSi2 template crystallize with the CsC1 structure with 50% vacancies on the cation lattice. The same is true for codeposited films nucleating from the amorphous phase at very low annealing temperatures (100–200 °C). Upon annealing a gradual transition to the stable bulk phase with the CaF2 structure takes place. For films grown onto a template, some grains of (CsCl)Co0.5Si remain stable up to at least 550 °C, while the films grown without a template are fully transformed.

An Electron Microscopic Study of Hydrogen Dissolution in FeTi

The intermetallic compound FeTi (with CsC1 structure) is a candidate material for hydrogen storage systems. FeTi forms iron titanium hydride (FeTiHx, where x represents a variable number of hydrogen atoms, up to about 2). In this study, electron microscopy has been used to study (a) the nature of the ‘activation’ process i.e. introduction of hydrogen in FeTi, (b) the morphology and structure of hydride phases and (c) the microstructure of the material after the subsequent removal of hydrogen. For this purpose the same region of the specimens were observed in the electron microscope (a) before the dissolution of hydrogen, (b) after the dissolution of hydrogen and (c) after the removal of hydrogen.