First principles study of structural, electronic and elastic properties of lutatium mono-pnictides

The structural, electronic, elastic and thermal properties of two lutatium mono-pnictides (LuAs and LuSb) have been studied using the density functional theory within the generalized gradient approximation. The calculations indicate that there is a structural phase transition from their ambient NaCl – (B1) to CsCl – (B2) structure at 56.7 and 25.2 GPa along with the volume collapse percentage of 3% and 5%, respectively. Structural parameters like lattice constant (a0), bulk modulus (B) and pressure derivative of the bulk modulus (B′) are presented. The calculated band structures indicate that B1 and B2 phase of these compounds are metallic. We have calculated the second order elastic constants for these compounds. We also compare the ground state (a0 and B) and high pressure phase transition (Pt) properties for three members of lanthanide series.

Research highlights
► The high pressure phase of LuAs and LuSb is predicted to be CsCl structure at 56.7 and 25.2 GPa respectively.
► The elastic constants of both compounds show that they are mechanically stable in NaCl structure.
► The lattice constant, bulk modulus and phase transition of three lanthanide (La, Gd and Lu) unfilled, half filled and completely filled with f-electrons of lanthanide series are compared.
► DOS and Band structure show that both the compounds (LuAs and LuSb) are metallic.