EXCIMER LASER INDUCED MODIFICATION OF CERAMICS SURFACE

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The aim of the present project is a surface modification of ceramics by excimer laser implantation. By this technique, it is possible to make a conductive thin layer and/or a special coating film on dielectric materials. The ceramics used in this experiment are quartz (SiO_2), alumina (Al_2O_3) and human dental enamel as hydroxyapatite (Ca_<10>(PO_4)_6(OH)_2). Au atoms were implanted into the oxides and Ag and F atoms were implanted into the enamel. The analysis for implanted part was done by Ratherford backscattering spectroscopy (RBS) for the depth distribution and X-ray micro analysis XMA for the plane distribution.The main features obtained in this project are as follows.1. SiO_2 and Al_2O_3These oxides were irradiated by excimer laser (<lambda>=248nm ,<tau>=23ns ) after vopour deposition of Au atoms on ceramics surface.(1)The amount of implanted Au atoms decreases with increasing irradiation energy density. Maximum amount was obtained at around 0.5 J/cm^2.(2)Maximum depth was 350nm for SiO_2 at [0.5 J/cm^2 and 650nm for Al_2O_3 at [0.2 J/cm^2.(3)The ratio ,Ns/Nb is a function of energy density where Ns and Nb are the amount of Au atoms near surface and in the bulk , respectively.(4)Above experimental results are completely different from that obtained by useing with IR- and visible-laser light.2. Ca_<10>(PO_4)_6(OH)_2In this case , CO_2 laser(<lambda>=10.6<micrn>m ,<tau>=0.5s ) irradiation was done fluoride (Ag(NH_3)_2F)- coated enamel surface.(1)Maximum depth of implanted F atoms was observed at 20 J/cm^2 and was about 1.2<micrn>m. This maximum depth is about 1.7 times larger than the case of an unirradiated enamel.(2)Part of Ag atoms was sputtered from enamel surface by laser irradiation.