Structure of the dense amorphous carbon phase synthesized in a mixture with diamond as a result of shock compression of carbon black

Abstract

Soft X-ray emission and absorption spectroscopy methods were used in the present work to study experimentally the electronic structure of the dense amorphous carbon phase synthesized in a mixture with diamond as a result of shock compression of carbon black. The X-ray emission C Kα bands, representing the energy distribution of the C 2p-like states, have been recorded for the amorphous carbon phase and, for comparison, for diamond, lonsdaleite, graphite, and carbon black. For the amorphous carbon phase, diamond and lonsdaleite the spectra of quantum yields of the X-ray photoeffect in the area of the C K absorption edge have been recorded as well. Total and partial densities of states of the carbon H-6 and bct-4 phases, diamond and lonsdaleite have been calculated using the first-principles self-consistent full potential linearized augmented plane wave (FP-LAPW) method. Comparison on a common energy scale of the X-ray emission C Kα bands and C K quantum yields of the dense amorphous carbon phase as well as the theoretical curves of partial C 2p-like states of the carbon H-6 and bct-4 phases reveals that, the electronic structure of the amorphous carbon phase under consideration is well described by that of the carbon bct-4 phase. The experimental X-ray emission and absorption spectroscopy data indicate that the amorphous carbon phase studied is metallic, being in agreement with the results of the theoretical FP-LAPW calculations.