Spectroscopic characterization and development of technique for high-pressure synthesis of carbon based nano-structural materials

To be able to study high pressure properties and synthesis of carbon nanostructures, we built a pressure control box to regulate and fine tune pressure to our membrane diamond anvil cell (MDAC). Using ruby fluorescence method, we calibrated the pressure in the membrane against the generated pressure in the cell. This resulted in both a pre-indentation pressure curve for hardened stainless steel gaskets and in a calibration curve for pressure in the membrane against generated pressure in the MDAC. Raman spectroscopy was used to characterize carbon nanostructures. Two kinds of carbon nanotubes (CNTs) were examined, one HiPCO and one Arc- discharged produced sample, with the purpose to see how side-wall functionalization affects their spectra. Spectra were acquired from pristine and functionalized samples with 532 nm (2,33 eV) and 632,8 nm (1,96 eV) excitations and compared. Both metallic and semiconducting tubes are being probed, and we can see that metallic- and small diameter semiconducting tubes are more affected compared to semiconducting tubes with larger diameters. Different types of polymeric fullerene samples were also characterized in order to determine their structure. Spectra from 1D and one kind of 2D polymeric fullerene samples were found. Multi wall CNT (MWNT) – epoxy composites, manufactured by SiCOMP, were examined with Raman spectroscopy to see how well the MWNT interacted with the epoxy matrix and to get an estimation of how well dispersed the MWNTs were in the matrix. Spectra were acquired from epoxy and MWNTs separately, and then compared with spectra acquired from the composites. We could not see any sign of interaction between the epoxy and the MWNTs, and the tubes do not seem to be that well dispersed in the matrix.

Author: Abrahamsson, David; Jonsson, Henrik

Source: Lulea University of Technology

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