Structural, elastic and mechanical properties of group III-nitrides in zinc-blend structure

The pressure induced crystal properties of group III-nitrides have been investigated by means of modified interaction potential model (MIPM) which consists of Coulomb, three-body and short-range overlap repulsive up to second neighbour ions, covalency effect and van der Waal’s interactions. These compounds exhibit first-order phase transition from their initial ZnS-type structure to NaCl-type structure at pressures 555, 21, 37 and 8.2 GPa for XN (X = B, Al, Ga and In) respectively. Their equation of state shows volume collapse of 3.6%, 17%, 16.53% and 17.73%. The elastic constants and thermophysical properties have also been obtained at zero and high pressures. The results are in good agreement with the experimental and theoretical data where available. This model is capable of explaining the phase transition, Cauchy’s discrepancy and elastic and mechanical properties successfully.

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► We have investigated the high-pressure structural transition of III-nitrides.
► A modified model (MIPM) (including the covalency effect) has been developed.
► Phase transition pressures are associated with a sudden collapse in volume.
► Our model is able to explain Cauchy violations.
► We have extended our study to elastic and mechanical properties of III-nitrides.