The simplest dense carbon allotrope: Ultra-hard body-centered tetragonal C4

Body-centered tetragonal C4: a viable sp3 carbon allotrope.

We have investigated by first principles the electronic, vibrational, and structural properties of bct C4, a new form of crystalline sp{3} carbon recently found in molecular dynamics simulations of carbon nanotubes under pressure. This phase is transparent, dynamically stable at zero pressure, and more stable than graphite beyond 18.6 GPa. Coexistence of bct C4 with M carbon can explain better ...

A Reinvestigation of a Superhard Tetragonal sp3 Carbon Allotrope

I 4 ¯ -carbon was first proposed by Zhang et al., this paper will report regarding this phase of carbon. The present paper reports the structural and elastic properties of the three-dimensional carbon allotrope I 4 ¯ -carbon using first-principles density functional theory. The related enthalpy, elastic constants, and phonon spectra confirm that the newly-predicted I 4 ¯ -carbon is thermodynami...

Tetragonal allotrope of group 14 elements.

Group 14 elements (C, Si, and Ge) exist as various stable and metastable allotropes, some of which have been widely applied in industry. The discovery of new allotropes of these elements has long attracted considerable attention; however, the search is far from complete. Here we computationally discovered a tetragonal allotrope (12 atoms/cell, named T12) commonly found in C, Si, and Ge through ...

A novel low compressible and superhard carbon nitride: body-centered tetragonal CN2.

A novel body-centered tetragonal CN(2) (4 units per cell), named as bct-CN(2), has been predicted here using our newly developed particle swarm optimization algorithm for crystal structure prediction. Bct-CN(2) is energetically much superior (3.022 eV per f.u.) to previously proposed pyrite structure and stable against decomposition into a mixture of diamond + N(2) or 1/3(C(3)N(4) + N(2)) above...

Spin liquid versus long range magnetic order in the frustrated body-centered tetragonal lattice