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Single and multiwalled nitrogen-doped carbon nanotubes were grown by chemical vapor deposition varying the feedstock composition between pure acetonitrile and ethanol/acetonitrile mixtures. The advantage of using CN sources that develop close vapor pressure values has been used in order to elucidate the effects of the reaction atmosphere in the synthesis of N-doped nanotubes. Our findings show that the morphology of the nanotube material depends strongly on the composition of the reaction atmosphere. When carrying out the experiments in an atmosphere solely determined by the vapor pressure of the feedstock components, improved homogeneity is achieved with pure CN sources or low concentration of the foreign solute. Under these conditions the temperature has strong influence in the diameter distribution.

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Zinc oxide tetrapod powders with high luminescent characteristics have been grown by simple evaporation and direct oxidation of zinc. Their structural and optical properties have been studied by transmission electron microscopy and by cathodoluminescence. The legs of the tetrapods have a pure hexagonal structure and form an arrowhead joint at the center. The tetrapod legs exhibit strong band edge and weak green luminescence. Monochromatic cathodoluminescence images show that the band-edge emission originates from the bulk of the legs, while the green emission emanates from the surface, indicative of it being related to oxygen vacancies. Low temperature cathodoluminescence shows a direct correlation of near-band-edge emission with specific sites within the structure.

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