Elastic properties and chemical bonding in ternary arsenide SrFe2As2 and quaternary oxyarsenide LaFeAsO - basic phases for new 38-55K superconductors

TL;DR

This study uses first-principles calculations to analyze the elastic properties and chemical bonding of SrFe2As2 and LaFeAsO, key phases in high-temperature superconductors with critical temperatures up to 55K.

Contribution

First comprehensive calculation of elastic properties and bonding characteristics of SrFe2As2 and LaFeAsO, providing essential data for understanding their superconducting behavior.

Findings

Elastic constants and moduli are quantitatively estimated.

Chemical bonding features are characterized.

Elastic parameters for polycrystalline ceramics are provided for the first time.

Abstract

We report the first-principle FLAPW-GGA calculations of the elastic properties of two related layered phases, namely, the ternary arsenide SrFe2As2 and the quaternary oxyarsenide LaFeAsO - basic phases for the newly discovered "122" and "1111" 38-55K superconductors. The independent elastic constants (Cij), bulk moduli, compressibility, and shear moduli are evaluated and discussed. The numerical estimates of the elastic parameters of the polycrystalline SrFe2As2 and LaFeAsO ceramics are performed for the first time. Additionally, the peculiarities of chemical bonding in these phases are discussed.