Ab-initio simulation of elastic constants for some ceramic materials

Athermal elasticity for some ceramic materials (α-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>, SiC (α and β phases), TiO<Subscript>2 </Subscript>(rutile and anatase), hexagonal AlN and TiB<Subscript>2</Subscript>, cubic BN and CaF<Subscript>2</Subscript>, and monoclinic ZrO<Subscript>2</Subscript>) have been investigated via density functional theory. Energy-volume equation-of-state computations to obtain the zero pressure equilibrium volume and bulk modulus as well as computations of the full elastic constant tensor of these ceramics at the experimental zero pressure volume have been performed. The present results for the single crystal elasticity are in good agreement with experiments both for the aggregate properties (bulk and shear modulus) and the elastic anisotropy. In contrast, a considerable discrepancy for the zero pressure bulk modulus of some ceramics evaluated from the energy-volume fit to the computational zero pressure volume has been observed. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007