Ternary inorganic compounds containing carbon, nitrogen, and oxygen at high pressures

2017/10/10 by Brad A. Steele, Steele, Brad A., Ivan I. Oleynik +1
Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #cond-mat.mtrl-sci

paper · pdf · doi:10.48550/arxiv.1710.03652

arxiv created 2017/10/10 · arxiv updated 2017/10/11

Abstract

Ternary C_xN_yO_z compounds are actively researched as novel high energy density and ultrahard materials. Although some synthesis work has been performed at ambient conditions, very little is known about the high pressure chemistry of of C_xN_yO_z compounds. In this work, first principles variable-composition evolutionary structure prediction calculations are performed with the goal of discovering novel mixed C_xN_yO_z materials at ambient and high pressure conditions. By systematically searching ternary variable composition crystalline materials, the full ternary phase diagram is constructed in the range of pressures from 0 to 100 GPa. The search finds the C₂N₂O crystal containing extended covalent network of C, N, and O atoms, having space group symmetry Cmc2₁, and stable above just 10 GPa. Several other novel metastable (CO)_x-(N)_y crystalline compounds discovered during the search, including two polymorphs of C₂NO₂ and two polymorphs of C₃N₂O₃ crystals are found to be energetically favorable compared to polymeric carbon monoxide (CO) and nitrogen. Predicted new compounds are characterized by their Raman spectra and equations of state.

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