Elasticity of (K,Na)AlSi3O8 hollandite from lattice dynamics calculations

International audience ; We compute the elastic constants tensor and the seismic properties of KAlSiO and KNaAlSiO up to the ferroelastic transition using density-functional theory and density-functional perturbation theory in the ABINIT implementation. We observe a softening of the tetragonal shear with pressure that precedes the ferroelastic transition. The Reuss shear moduli become negative at respectively 23GPa and 13GPa for the two compositions considered in here. The ferroelastic transition is associated with a strong decrease of the horizontal shear wave velocities and a corresponding i... Mehr ...