Functional Bi Coatings as a Perspective Material for Radiation Shields Production against Electron Radiation

Abstract

Aligned, highly uniform multiwall carbon nanotubes (MWCNT) in a porous anodic aluminum oxide (AAO) membrane were successfully grown by chemical vapor deposition (CVD). The effectiveness of MWCNT formation was studied with various synthesis parameters. It was found that high catalyst (ferrocene) concentrations led to formation of a thick layer of MWCNT arrays on top surface of AAO membranes, which led to decrease of the pores filling with nanotubes. It was shown that the growth mechanism of the nanotubes in the AAO pores by this method was not connected with the traditionally used transition metal catalysts, no matter whether they were in a deposited (localized catalyst) or volatile (injected catalyst) state. The pre-annealing process in air atmosphere inhibited the nanotubes formation in the AAO pores. We speculate that the formation of MWCNT s in the AAO pores is governed by the pore structure reconstruction (water desorption, phase transformation) during the high-temperature (870°C) CVD process, though this phenomenon needs further investigation.