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ZB 19 - Characterization of processes in first atomic layers of a solid surface (A.Jablonski)


Biomaterials, SERS active substrates, conductors for oxygen ions, physico-chemical investigation of the surface materials. M.Pisarek, A.Roguska, M.Holdynski

To date, studies of modified Ti surfaces for biomedical purposes have concentrated on observations of morphology and identifying their physicochemical properties. A promising approach to meet the above requirements it to create modern type of composite coatings on Ti substrate, namely Ca-P/Ag/TiO2 composite coatings, with well-defined microstructure, chemical and phase composition, controlled porosity and surface topography. Preliminary studies have shown that TiO2 nanotubes fabricated via anodization technique have ordered structure and their growth is perpendicular to Ti substrate. The specific surface morphology of TiO2 nanotubes facilitates the formation of calcium phosphate (Ca-P) layers under physiological conditions. Additional loading of the resulted coatings with Ag nanoparticles with diameter of 2 ? 50 nm using sputter deposition technique  is expected to provide antiseptic properties. Composite layers on Ti consisting of bioactive ceramic coating and Ag nanoparticles should have a positive impact on the osteoblasts activity and prevent bacterial adhesion to the implant surface. Moreover, nanoporous oxide layers (TiO2, Al2O3) decorated with nanoparticles of Ag, Au or Cu can be used as model substrates for SERS investigations. Such systems may be particularly active substrates capable of increasing the cross sections for Raman scattering of adsorbed organic molecules (e.g. pyridine) to a degree much higher than is possible on the electrochemically roughened surfaces of SERS active metals. SERS spectra of molecules adsorbed on the surface of new nano-structured materials will allow to understand electromagnetic (depending on the morphology) and chemical (the effect of CT (charge transfer) transition associated with a partial charge between adsorbate and adsorbent) effects. SERS investigation using substrates with variable nanoporous morphology and different sizes of metal nanoparticles, is of particular interest since the reduction in size of material through the nanoscale regime (< 100 nm) can lead to a new chemical n\and physical properties clearly different from the bulk counterparts of those materials.
Using simple methods of chemical synthesis of oxides based on rare-earth in aqueous solutions of organic acids, combined with heat treatment can lead to create a new generation of nanomaterials (oxygen ions conductors based on CeO2). These types of materials that can be used as solid electrolyte for intermediate-temperature solid oxide fuel cells (SOFC) or oxygen pumps, are showing a higher ionic conductivity in the temperature range 500oC - 700oC  than stabilized zirconia (YSZ) used so far. Low working temperature of electrolytes based on CeO2 and stability in a reducing atmosphere (in contrast to materials based on Bi2O3) can allow for their wider use.