The structural, electronic, and mechanical properties of FeH under extreme pressures: First-principles calculation

Abstract

The structural, electronic, and mechanical properties of FeH binary compound under 0–300 GPa were investigated by first-principles calculation. It is proved that the FeH is stable under 0–300 GPa using mechanically stable criteria and phonon spectra. Firstly, the electronic properties of Fe–H compounds were studied by density of states and the band structures. FeH shows its metallic properties under extreme pressure. Secondly, the elastic constant, bulk modulus and shear modulus of FeH increase with the increase of pressure, and the values of above physical quantities for Fe–H binary compounds decrease with the higher content of H. In addition, Poisson's ratio revealed its essence of ionic crystal. Thirdly, Vickers hardness(Hv) and Young's modulus(E) of FeH increase with the pressure, and the smaller content of H in Fe–H binary compound implies the bigger Hv and E. Last but not least, the existence of H in Fe might increase the Vp compared with that of pure Fe which is higher than PREM's. Therefore, Fe–H binary compounds might not be a suitable model for Earth's core. There might be some other elements in the earth interior.