Investigation of the mechanical and thermodynamic properties of the U3Pt4 and Th3Pt4

The elastic, Vickers hardness and anisotropy properties of A3Pt4 (A = U and Th) have been extensively investigated by the first principles calculations. The obtained equilibrium lattice parameters are in good agreement with the available experimental data. The calculated elastic constants meet the mechanical stability conditions, demonstrating that A3Pt4 are mechanically stable. The bulk modulus, Young's modulus, shear modulus and hardness of A3Pt4 were calculated. The results reveal that both of them are ductile, and the hardness is 0.26 GPa and 2.7 GPa for U3Pt4 and Th3Pt4, respectively. The elastic anisotropy was characterized by several different methods. The results demonstrate that the anisotropy of U3Pt4 is more prominent than Th3Pt4. Furthermore, through the quasi-harmonic Debye (QHD) model, the temperature dependence of thermodynamic properties of A3Pt4 has been obtained. Our theoretical calculations suggest that the Cv and Cp of A3Pt4 are increase with increasing temperature, and the Cv is about 173.07 J/mol.K and 170.65 J/mol.K at 300 K, respectively. The Cp of A3Pt4 are good agreement with the available experimental data in the low temperature region. Finally, the Debye temperature θD and the minimum thermal conductivity Kmin were obtained, and further analyses show that A3Pt4 are potential thermal insulating materials.