Elastic properties of Sr_n+1Ti_nO_3n+1phases (n= 1–3, \infty )

Abstract

Using ab initio calculations, we have studied the correlation between the electronic structure and elastic properties of Srn+1TinO3n+1 (space groups and I4/mmm; n = 1–3, ). These ternary oxides possess an unusually large bulk modulus to C44 ratio and the Peierls stress is comparably low. This may be understood on the basis of the electronic structure: ionic–covalent layers (Ti–O) are interleaved with metallic layers (Ti–Sr and Ti–Ti). We suggest that the large bulk modulus to C44 ratio and low Peierls stress are the result of weak coupling between the ionic–covalent and metallic layers, causing the low C44 value, as well as strong coupling within ionic–covalent layers, causing the large bulk modulus.