Synthesis of carbon nanotubes directly over TEM grids aiming the study of nucleation and growth mechanisms

A novel approach to produce electron-transparent multi-layer membranes over TEM grids for transmission electron microscopy analysis is presented. The membranes have been used to grow and analyze carbon nanostructured materials in a thermal-chemical vapor deposition process using Ni and Cu as catalysts and silicon oxide thin films as support layers, at temperatures as high as 900 °C. It is important that conditions of the synthesis using the electron-transparent multi-layer membrane system are similar to those for a conventional chemical vapor deposition process, where oxidized silicon wafers are employed. In particular, the thickness of the silicon oxide and the catalyst layers are the same, and similar carbon tubular structures were grown using both substrates. The use of membranes was crucial especially for the study of the nucleation mechanism for carbon nanotubes. These electron-transparent multi-layer membranes are relatively easy to obtain and they can be used for transmission electron microscopy studies of high-temperature synthesis of different nanostructured materials.