Abstract:
Compounds belonging to the 122 iron pnictide have a ThCr2Si2 structure with a space group of 14/mmm containing divalent alkali earth metal elements. This study applies First Principle Calculation to investigate mechanical, electronic and structural phase transition properties. The compound has a low value of Vicker hardness an indication that it is not strong enough to resist being dented. This property enables them suitable for the use as bake hardeners which provide a good formability before stamping and enhance strength post baking. It has low value of Debye temperature hence frozen high frequency modes are expected that enhances field amplitude which can be very attractive in various applications such as dispersion engineering, lasers and delay lines. The compound is metallic. The compound has phase transition from the stable phase non-superconducting tetragonal to type I orthorhombic superconducting phase. This plays a big role in enhancing conductivity. We are making use of the Quantum Espresso simulation package which is a suite for First Principles electronic structure calculations and material modelling distributed for free under free software for the General Public License. It has its basis on plane wave basis sets, density functional theory, and pseudopotentials both ultrasoft and norm-conserving. Quantum Espresso runs many calculations with powerful parallel machines, workstations and computer systems. These calculations involve ground state calculations, structural optimization, electrochemistry and special boundary conditions, response properties, spectroscopic properties and Quantum transport. The elastic constants indicate the deformation resistance along the axes and planes of the material under study. The band structure which represent the allowed electronic energy levels of solid materials, gives information on the material's electrical properties. It consists of the valence and conduction bands which overlaps. Between the conduction and valence bands the compound has superconducting gaps. The superconducting gaps are the energy differences between the valence band's highest points and the conduction band's lowest points. At external pressure application of 0.2GPa, the compound achieves phase transition and superconductivity emerges due to the reduction of the unit cell volume. The projected Density of states gives the number of states per energy range between the bands and shows the orbitals responsible for the conductivity. The phase change properties are brought about by changes in the conditions which induce desirable characteristics, for instance, superconductivity. Our results indicate that the compound is stable mechanically and with application of pressure it undergoes phase transition at 0.2GPa. From Density of states calculation, increase in energy results to phonon hardening a property which can be studies for its good application in integrated circuits.
