Elastic properties of quaternary oxyarsenide LaOFeAs as basic phase for new 26-52K superconductors

TL;DR

This study uses first-principles calculations to predict the elastic properties of LaOFeAs, a key phase in high-temperature superconductors, revealing its mechanical stability, softness, and bonding characteristics.

Contribution

First numerical estimates of elastic parameters for polycrystalline LaOFeAs ceramics using FP-LAPW and GGA methods.

Findings

LaOFeAs is mechanically stable and anisotropic.

It is a soft material with high compressibility.

It exhibits a high ionic bonding contribution.

Abstract

The full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential has been applied to predict the elastic properties of quaternary oxyarsenide LaOFeAs - the basic phase for the newly discovered 26-52K superconductors. The optimized lattice parameters, independent elastic constants (Cij), bulk modulus B, compressibility betta, and shear modulus G are evaluated and discussed. For the first time the numerical estimates of the elastic parameters for polycrystalline LaOFeAs ceramics are performed. Our analysis shows that LaOFeAs belong to the anisotropic mechanically stable systems; a parameter limiting the mechanical stability of this material is the shear modulus. In addition, LaOFeAs is a soft material (B -98 GPa) with high compressibility (betta - 0.0102 1/GPa); lays at the border of a brittle behavior and adopts a high ionic contribution in intra-atomic bonding.