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 characterized by nanoscale cavities of uniform size separated by microscopically thin metal walls. The oxidation of such structures with volume fractions of approximately 20%, is investigated. High levels of lateral stress are evident in the implanted V specimens. A combination of TEM and IBA is used to show that when such structures are thermally oxidized in flowing oxygen at temperatures up to 400°C: (i) an abrupt interface is maintained between the growing oxide layer and the underlying V (which is also the case for compact V); (ii) the underlying bubble structure is preserved; (iii) unexpectedly, the oxygen uptake is slightly inhibited compared with that for compact V, and; (iv) the formation of V 2O 5 is favored over V 3O 7 when compared with compact V.