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 demonstrate d on sintered alumina. Focusing on surface versus bulk crystallographi c transformations, normal incidence and low-angle X-ray diffraction an alyses have been used to investigate irradiated substrates. In particu lar, it is shown how excimer irradiation induces melt/quench procedure s which may be tuned, as a function of the irradiation parameters, to produce various degrees of ordering in the solidified material. In par ticular, a set of irradiation regimes are shown to induce the exclusiv e emergence of the alumina gamma-phase at and within 10 nm from the su rface 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 pres ence is further demonstrated in an electroless procedure by immersing the irradiated substrates in an autocatalytic bath containing di-valen t metal ions which are driven to occupy vacant sites at and close to t he surface, hence demonstrating an interesting potential for the devel opment of a novel and efficient metallization process for sintered alu mina.