SURFACE-PROPERTIES OF EXCIMER-LASER-IRRADIATED SINTERED ALUMINA

In this presentation, the potential of excimer laser irradiation as a tool for tailoring the physical properties of materials is demonstrated on sintered alumina. Focusing on surface versus bulk crystallographic transformations, normal incidence and low-angle X-ray diffraction analyses have been used to investigate irradiated substrates. In particular, it is shown how excimer irradiation induces melt/quench procedures which may be tuned, as a function of the irradiation parameters, to produce various degrees of ordering in the solidified material. In particular, a set of irradiation regimes are shown to induce the exclusive emergence of the alumina gamma-phase at and within 10 nm from the surface of the material. The phenomenology of this gamma-phase synthesis is described and further modelled taking into account the presence in its lattice of periodically distributed cationic vacancies. This presence is further demonstrated in an electroless procedure by immersing the irradiated substrates in an autocatalytic bath containing di-valent metal ions which are driven to occupy vacant sites at and close to the surface, hence demonstrating an interesting potential for the development of a novel and efficient metallization process for sintered alumina.