TEM AND IBA STUDY OF THE THERMAL-OXIDATION OF V FOLLOWING HIGH-DOSE HE IMPLANTATION

High dose He implantation in V can lead to the formation of He bubble arrays with high cavity volume fractions. These structures, which are of interest in relation to applications such as catalysis, are charact erized by nanoscale cavities of uniform size separated by microscopica lly thin metal walls. The oxidation of such structures with volume fra ctions of approximately 20%, is investigated. High levels of lateral s tress are evident in the implanted V specimens, A combination of TEM a nd IBA is used to show that when such structures are thermally oxidize d in flowing oxygen at temperatures up to 400 degrees C: (i) an abrupt interface is maintained between the growing oxide layer and the under lying V (which is also the case for compact V); (ii) the underlying bu bble structure is preserved; (iii) unexpectedly, the oxygen uptake is slightly inhibited compared with that for compact V, and; (iv) the for mation of V2O5 is favored over V3O7 when compared with compact V.