High pressure lattice dynamics and stress-strain responses of LaIn3 and LaTl3

Abstract

A detailed study of the ground state structure, non-zero elastic constants, high pressure lattice dynamics as well as theoretical tensile and shear strengths of the cubic intermetallic compounds LaIn3 and LaTl3 with AuCu3 (L12)-type has been made through first-principles. The optimized equilibrium crystal constants, cell volumes, bulk modulus and its pressure derivative, and single-crystalline elastic constants are in fair agreement with available experimental data and other calculations. More importantly, high pressure phonon spectrum, total and partial phonon densities of states in LaIn3 and LaTl3 up to 10 GPa are reported by employing Density Functional Perturbation Theory (DFPT), and the present results have demonstrated that both systems are dynamically stability up to 10 GPa. The differences between the dynamical properties of LaIn3 and LaTl3 have also been discussed systematically. Additionally, the tensile and shear stress-strain responses and the theoretical strengths of LaIn3 and LaTl3 are further calculated, we have found that LaIn3 exhibits larger tensile and shear strengths than LaTl3. These investigations are expected to provide beneficial references for further exploring the physical properties of rare earth compounds.