Elastic properties of amorphous boron suboxide based solids studied using ab initiomolecular dynamics

Abstract

We have studied the correlation between chemical composition,structure, chemical bonding and elastic properties of amorphousB6O based solids using ab initio molecular dynamics. These solids are of different chemicalcompositions, but the elasticity data appear to be a function of density. This is inagreement with previous experimental observations. As the density increases from 1.64 to2.38 g cm−3, the elastic modulus increases from 74 to 253 GPa. This may be understood by analyzing thecohesive energy and the chemical bonding of these compounds. The cohesive energy decreases from−7.051 to−7.584 eV/atom in the elastic modulus range studied. On the basis of the electron density distributions,Mulliken analysis and radial distribution functions, icosahedral bonding is the dominatingbonding type. C and N promote cross-linking of icosahedra and thus increase the density,while H hinders the cross-linking by forming OH groups. The presence of icosahedralbonding is independent of the density.