Theoretical investigation of Zr2PbC, (V0.25Zr0.75)2PbC, (V0.5Zr0.5)2PbC, V0.75Zr0.25)2PbC, and V2PbC MAX phases: a DFT based study

Abstract

The structural, elastic, and electronic properties of new nanolaminates (V0.25Zr0.75)2PbC, (V0.5Zr0.5)2PbC, (V0.75Zr0.25)2PbC, and V2PbC are investigated for the first time by applying density functional theory. These properties are investigated at different V and Zr concentrations in Zr2PbC at ambient conditions. The fully relaxed and optimized structural parameters a (Å), c (Å), and V (Å3) maintain the dimensions of the parent material. Elastic constants Cij have been calculated to investigate the mechanical behaviour of these MAX compounds. The calculated elastic moduli show that Zr and, or V containing new MAX compounds are more anisotropic than the parent bulk Zr2PbC, with improved ductility. The compressibility, brittleness, and hardness (at V = 25% is seen to increase while it decreases in the V = 50%, 75%, and the bulk V2PbC MAX phases). The elastic constants results reveal an increment in their magnitude as the concentration of V increases. Moreover, the electronic band structure and total density of states (TDOS) of these MAX compounds experience considerable evolution due to changes in atomic concentrations. The electronic bands and TDOS depict metallic characteristics with impact largely from the Zr-4d and V-3d states. The density of states shows a significant increase at the Fermi level as the concentration of V in Zr2PbC is increased.