Effect of Pressure on Structural and Elastic Properties of Noncentrosymmetric LaPtGe3 Studied by ab-initio Method

The structural and elastic characteristics of LaPtGe3 were reported using density functional theory (DFT) implemented in the CASTEP code. The study reveals significant pressure-induced effects of external pressure on these properties. The lattice parameter c changes more than a and b under pressure, highlighting the anisotropic nature of LaPtGe3. The reduction in unit cell volume under pressure mainly arises from shifts in the positions of Ge and Pt atoms. As pressure increased, bond lengths decreased, with the most pronounced reduction shows in Ge-Ge bonds. This contraction in bond lengths contributed to the decrease in unit cell volume and influenced other related properties of the material. The calculated elastic constants of LaPtGe3 at both ambient conditions and under external pressure adhered to the Born–Huang stability criteria, confirming the material’s mechanical stability. With increasing pressure, the bulk modulus of LaPtGe3 rose, indicating that the material became harder. Additionally, Pugh’s ratio, which exceeded 1.75, suggested a ductile nature, and this ductility further increased with applied pressure. This behavior was corroborated by Poisson’s ratio, which also indicated enhanced ductility under higher pressure. An analysis of the anisotropy factor revealed that LaPtGe3 remained elastically anisotropic across the applied pressure range of 0 to 25 GPa, as the factor remained below unity. A strong anomaly was indicates at approximately 15 GPa in several properties, including shear modulus, Young’s modulus, Pugh’s ratio, Poisson’s ratio, and the universal anisotropic factor. This anomaly is likely associated with a structural phase transition in LaPtGe3, marking a significant change in its mechanical and elastic behavior under high-pressure conditions.