SYNTHESIS OF OXIDE SUPERALLOYS BY ML-ALE METHOD

Synthesis by molecular layering (ML-ALE) of chromium oxides and aluminium oxides superalloys was studied in the present work. The process was conducted by sequential supply of two reactants - trimethyl aluminum (TMA) and chromyl chloride. We used the oxidation-reduction reaction between these reactants in this ML-ALE method. It was found that synthesis of the layer took place in the temperature range from 25 to 200-degrees-C. The ''processing window'' was 100-200-degrees-C. The composition of the layer measured by ESCA corresponds to the formula CrAl2O5. Ellipsometric measurements showed that the synthesis of chromium and aluminum oxides took place in a layer-by-layer manner. The calculation of the fully optimized structure was carried out with a CNDO program attached to a MOBY system. Chromium atoms are situated at the centre of the tetrahedron, the oxygen atoms occupy vertices, and two aluminum atoms are attached to a couple of oxygens at the periphery of a cell. Each structural subunit is linked to others by bridged oxygens and closely attached to other tetrahedrons so that the tetrahedral oxygens are shared between neighboring tetrahedrons.