First-Principles Calculations on Phase Transition and Elastic Properties of CoN

Abstract

The structural phase transition and elastic properties of CoN are investigated by ab initio plane-wave pseudopotential density function theory method. The equilibrium lattice parameters a0, elastic constants Cij, bulk modulus B0 and its derivative B0 are calculated. From the usual condition of equal enthalpy, the phase transition of CoN from zinc-blende to rocksalt structure occurs at 35.4 GPa with a volume collapse of about 15.6%, consistent with the calculated result 36 GPa (FP-LDA), but an uncertainty is about 4.4 GPa compared with the 31 GPa (ASA-GGA). All three independent elastic constants, C11, C12, and C44 for CoN are calculated from direct computation of stresses generated by small strains. Both C12 and C44 are less sensitive to pressure as compared with C11. The calculated conclusions offer theoretical data for the further research of the mechanical properties for CoN.

X-ray absorption spectroscopy study of cobalt mononitride thin films

“…Though theoretical works predict both ZBand RS-type structures for FeN and CoN, but under ambient temperature and pressure, the ZB-type structure is preferred [21]. The energy minima in the total energy-volume plots is lower in ZB, as compared to that in RS CoN [21,22,[37][38][39][40]. Under high pressure, a phase transition from ZB-to RS-type phase is expected at about 50 GPa in FeN [33] and about 40 GPa in CoN [22].…”

Study of Structural & Magnetic Properties of CoN Thin Films

“…Though theoretical works predict both ZB and RS-type structures for FeN and CoN but under ambient temperature and pressure, the ZB-type structure is preferred [21]. The energy minima in the total energy-volume plots is lower in ZB, as compared to that in RS CoN [21,22,[30][31][32][33]. Under high pressure, a phase transition from ZB to RS-type phase is expected at about 50 GPa in FeN [26] and about 40 GPa in CoN [22].…”