Pressure effect on stabilities of self-Interstitials in HCP-Zirconium
نویسندگان
چکیده
The self-interstitial atoms (SIAs) mediate the evolution of micro-structures which is crucial in understanding the instabilities of hexagonal close packed (HCP) structures. Taking zirconium as a prototype, we investigate the pressure effect on the stabilities of SIAs using first-principles calculations based on density-functional theory. We found that the pressure greatly affects the stability of the SIAs. The SIAs in basal planes are more stable under pressure. The SIA configuration of the lowest formation energy changes from basal octahedral (BO) to octahedral (O) at a pressure of 21 GPa. The lowest formation enthalpy configuration switches from BO to S (split-dumbbell) at the pressure of 30 GPa. The formation volumes of SIAs decrease monotonically in response to an increase in pressure. Our results reveal that it is important to take pressure effects into account when predicting the micro-structural evolution of HCP structures.
منابع مشابه
Ab Initio Study on the Electronic Band Structure, Density of States, Structural Phase Transition and Superconductivity of Zirconium
The electronic band structure, density of states, structural phase transition and super conducting transition temperature of group –IV B element Zirconium (Zr) under normal and high pressure are reported. The normal pressure band structure, density of states and superconducting transition temperature of hcp Zr agree well with the previous calculations. The high pressure band structure exhibits ...
متن کاملRoom-temperature structures of solid hydrogen at high pressures.
By employing first-principles metadynamics simulations, we explore the 300 K structures of solid hydrogen over the pressure range 150-300 GPa. At 200 GPa, we find the ambient-pressure disordered hexagonal close-packed (hcp) phase transited into an insulating partially ordered hcp phase (po-hcp), a mixture of ordered graphene-like H(2) layers and the other layers of weakly coupled, disordered H(...
متن کاملTexture changes in the hcp! bcc! hcp transformation of zirconium studied in situ by neutron diffraction
The crystallographic texture of hot-rolled polycrystalline zirconium has been studied below and above the hcp–bcc transition temperature with HIPPO, the new time-of-flight neutron diffractometer at Los Alamos Neutron Science Center, making use of the multidetector capabilities and a vacuum furnace. Incomplete pole figures were extracted from diffraction spectra to determine the orientation dist...
متن کاملSolutions of diffusion equation for point defects
An analytical solution of the equation describing diffusion of intrinsic point defects in semiconductor crystals has been obtained for a one-dimensional finite-length domain with the Robin-type boundary conditions. The distributions of point defects for different migration lengths of defects have been calculated. The exact analytical solution was used to verify the approximate numerical solutio...
متن کاملThe effect of iodo substituents in bis(phenoxyimine) zirconium complexes on the catalytic performance of homogeneous ethylene polymerization reactions
Eight different zirconium phenoxyimine complexes were synthesized, characterized and tested as catalysts for ethylene polymerization. The phenoxyimine compounds were prepared by condensation of substituted salicylaldehydes with aliphatic and aromatic amines, the substituted salicylaldehydes from ortho substituted phenols and paraformaldehyde. The introduction of iodo substituents was achieved e...
متن کامل