Hydrogen storage properties, structural analysis, elastic and electronic properties of K2PdH4

Abstract

Density functional theory is adopted to study phase transitions and structural, elastic, and electronic properties of hydrogen storage K2PdH4. First, the structural evolution of K2PdH4 is investigated under high pressure along with the hydrogen storage properties. In the ambient conditions, K2PdH4 crystallizes in a tetragonal structure with space group I4/mmm. As the pressure is increased gradually on the crystal, a phase transition is recorded to the orthorhombic structure with space group Immm. Subsequently, the density of states and electronic band structures are obtained for each phase. Mechanical properties such as ductility and brittleness are investigated using elastic constants which are crucial parameters for solid-state hydrogen storage materials. Moreover, several properties are analyzed using Young, shear and bulk modulus to reveal the bonding characteristics of K2PdH4.