Ab initio studies of the electronic structure of the quaternary system LiBC4N4

Starting from experimental data on the synthesis of solid LiBC4N4, an ab initio study has been carried out within the DFr-LDA framework of its structure and completed by accounting for other potential cubic arrangements. The consideration of stabilization energies confirms the experimental phase as the most stable one but predicts some other potential arrangements. The system is found very compressible with a bulk modulus close to that of gypsum (B-0 = 35 GPa). The electronic structure characteristics are provided allowing to confirm an ionic behavior involving complex anionic species (Li+[B(CN)(4)](-)). The control of the crystal cell size by a stoichiometry modification, such as by a CN group substitution is also studied. The proposition of LiBX4 and LiBS4N4 stoichiometries leads to predict new materials. (c) 2006 Elsevier B.V. All rights reserved.