First Principles Study of High-Pressure Phases of ScN

Abstract

We report the results of first-principles total-energy calculations for structural properties of scandium nitride (ScN) semiconductor compound in NaCl-type (B1), CsCl-type (B2), zincblende-type (B3), wurtzite-type (B4), NiAs-type (B81), CaSi-type (Bc), B-Sn-type (A5), and CuAu-type (L10) structures. Calculations have been performed with the use of the all-electron full-potential linearized augmented plane wave FP-LAPW method based on density-functional theory (DFT) in the generalized gradient approximation (GGA) for the exchange correlation energy functional. We predict a new phase transition from the most stable cubic NaCl-type structure (B1) to the B-Sn-type one (A5) at 286.82 GPa with a direct band-gap energy of about 1.975 eV. Our calculations show that ScN transforms from the orthorhombic CaSi-type structure (Bc) to A5 at 315 GPa. In agreement with earlier ab initio works, we find that B1 phase transforms to Bc, L10, and B2 structures at 256.27 GPa, 302.08 GPa, and 325.97 GPa, respectively. The electronic structure of A5 phase shows that ScN exhibits a direct band-gap at X point, with Eg of about 1.975 eV.

Structural and Mechanical Properties of Orthorhombic Libeh3: AB-Initio Study

“…The mass density of the substance called also the gravimetric density is the ratio of the mass to the volume; it is expressed in kg/m 3 or in g/cm 3 . It is given as follows: [45][46][47], where M is the molecular weight, which is expressed in 10 -3 kg, Z is the number of molecules per unit cell, V is the unit cell volume, which is expressed in m 3 , and NA is the Avogadro's number.…”