High Pressure Effects on the Structural Properties of GaN Compound Using Equations of State

The present study is a theoretical calculation for the effects of high pressure on thermodynamic properties on GaN up to 40Gpa at room temperature. Volume compression ratio (V-0/V-p), lattice constant (a) and elastic bulk modulus(B) have been established. Furthermore, lattice frequencies and disruptions function by analyzing phonon frequency spectrum (PFS) at (0 K). The entire calculations rely on using of two equation of state (EOS) Birch-Murnaghan and modified Lennard-Jones equation of state and with the integration of Gruneisen approximation theory. From the considered equations of state, formulation of bulk modulus was derived, that predicts a rising trend of bulk modulus. The large bulk modulus value of GaN has made a small fraction of change in volume (less than 15%) of the material even under an extreme pressure up to 45Gpa. It was also found that the results of phonon frequency spectrum obtained from Birch-Murnaghan equation of state in a better agreement with the experimental data than that of modified Lennard-Jones equation of state. Given that the Birch-Murnaghan equation of state developed according to Eulerian strain theory accounted as a universal equation of state. Moreover, good agreement between theoretically present calculations and experiment data of phonon frequency spectrum, reveals the validity of the equations of state used in the present study.

Automated summary

The present study conducts a theoretical calculation to analyze the effects of high pressure on the thermodynamic properties of GaN. The results show that the bulk modulus of GaN increases with pressure, while the volume change is relatively small. Additionally, the theoretical calculations are in good agreement with experimental data, indicating the validity of the equations of state used in this study.