Growth of ruthenium dioxide nanostructures by micro-afterglow oxidation at atmospheric pressure

Various ruthenium dioxide nanostructures were grown locally by the oxidation of ruthenium samples with an Ar-O2 microwave micro-afterglow operated at atmospheric pressure. A special attention was paid to the distribution of the surface temperature of the sample which evolves between 530 K and 820 K. Whatever the treatment time, the temperature and the gas composition set within the studied ranges, a general nanostructure, made of lamellae separated by 20-50 nm, is found. When the temperature rises, localized nano-sea urchins, nanotubes with square sections, nano-needles, and more complex structures are found spread over the surface. Treated surfaces were characterized by different surface diagnostics (SEM, XRD, SIMS, etc.) Finally, a growth mechanism is proposed emphasizing the role of emerging defects and stress on the appearance of localized nanostructures.