Porous CY carbon: a new semiconducting phase with an sp1-sp2-sp3 bonding network

A new carbon allotrope consisting of 16 atoms in an orthorhombic cell with a porous structure and displaying an Imma symmetry (termed as CY carbon) with a low mass density of 2.27 g cm(-3) was identified by first-principle calculations. The new carbon phase had an sp(1)-sp(2)-sp(3) network. Phonon dispersion confirmed that the allotrope was dynamically stable, whereas the elastic constants implied its mechanical stability. Analysis of the electronic band structure showed that this new carbon crystal was a direct semiconductor. The X-ray diffraction patterns and Raman spectra of the material were also simulated for the future experimental characterizations. A peak of 591 cm(-1) in the Raman spectrum revealed that a low-frequency feature can also exist in other carbon crystals besides just amorphous carbon. Due to the direct gap and porous character with low mass density, this new 3D porous semiconducting carbon allotrope may possess potential not only in electronic and optical applications but also in gas absorption applications.