Síntese de nanotubos de carbono orientados e aplicação na produção de pontas de AFM / Oriented growth of carbon nanotubes and application in production of afm Tips

AUTOR(ES)

Fernando Massa Fernandes

DATA DE PUBLICAÇÃO

2008

RESUMO

In this work multi walled carbon nanotubes (MWCNT) were obtained. The growth presented high density nanotubes oriented perpendicularly to the substrate, with about 20 m length and diameters between 20 and 60 nm. Catalytic films containing iron were used. These films were deposited from solution of iron nitrate (Fe(NO3)3.9H2O) in ethyl alcohol with concentrations that varied between 37 mmol / L and 1.2 mmol / L. It was not observed significant difference among the grown nanotubes obtained with different concentrations, except from the solution of 0.6 mmol / L, where the nanotubes growth was not observed. The growths of carbon nanotubes were obtained in a microwave plasma CVD reactor. The Raman spectroscopy suggests that the carbon nanotubes obtained in this work correspond to MWCNT, presenting high degree of structural disorder. Direct growths of carbon nanotubes on commercial AFM tips were performed, using films of iron nitrate. The nanotubes grown directly on the tips presented tendency in forming agglomerates. They were not obtained satisfactory AFM tips with this method. Another method consisted of carbon nanotubes growth on flat silicon substrates, using catalytic film of iron nitrate, with subsequent nanotubes capture at the extremity of the tip, using a microscope AFM. Altogether 26 procedures were performed, where most of their results were not satisfactory. In just two of these procedures were obtained very good results with straight and protuberant carbon nanotubes emerging of the tips. Still in this work a method of tip recycling was developed. The process is valuable, since the success in obtaining AFM tips with nanotubes occurs in just a fraction of the attempts, generating a representative number of lost tips. The tips recycling were performed through the corrosion of the carbon nanotubes in hydrogen plasma. The equipment used for this purpose was the microwave plasma CVD reactor, also used for carbon nanotubes growth.

ASSUNTO(S)

pontas de afm tips nanotubos de carbono carbon nanotubes afm tips

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