First-principles calculation of Mg/MgO interfacial free energies

Xu, Weiwei; Horsfield, Andrew P.; Wearing, David; Lee, Peter

doi:10.1016/j.jallcom.2015.07.289

Cited by 24 publications

(4 citation statements)

References 58 publications

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“…For all the alloys, it appears that the majority of the grains nucleated on the sample wall and grew towards the sample center. This is potentially due to the MgO / 31 skin on the surface acting as heterogeneous nucleation sites for the α-Mg grains [38] [39]. With increased solid fraction, an increase in the image contrast was observed.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys

et al. 2018

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Dendritic microstructural evolution during the solidification of Mg-Zn alloys was investigated as a function of Zn concentration using in situ synchrotron X-ray tomography. We reveal that increasing Zn content from 25 wt.% to 50 wt.% causes a Dendrite Orientation Transition (DOT) from a six-fold snowflake structure to a hyper-branched morphology and then back to a six-fold structure. This transition was attributed to changes in the anisotropy of the solid-liquid interfacial energy caused by the increase in Zn concentration. Further, doublon, triplon and quadruplon tip splitting mechanisms were shown to be active in the Mg-38wt.%Zn alloy, creating a hyper-branched structure. Using the synchrotron tomography datasets, we quantify, for the first time, the evolution of grain structures during the solidification of these alloys, including dendrite tip velocity in the mushy zone, solid fraction, and specific surface area. The results are also compared to existing models. The results demonstrate the complexity in dendritic pattern formation in hcp systems, providing critical input data for the microstructural models used for integrated computational materials engineering of Mg alloys.

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Section: Materials and Experimental Methodsmentioning

confidence: 99%

Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys

et al. 2018

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“…Their values can be ob-tained from DFT calculations of the total energies of appropriate systems modeling the heterostructure as well as the bulk crystals and slabs with a vacuum layer. The methodology details (from choosing the interface model up to the optimization methods) differ between implementations [12,27]. Here we focus on the approach in which two crystalline solids (X and Y) form a supercell with imposed periodic boundary conditions, that is, there are two interfaces within the supercell.…”

Section: Methodology Interfacial Energy and The Work Of Separation In...mentioning

confidence: 99%

Density functional theory study of Au-fcc/Ge and Au-hcp/Ge interfaces

Sikora,

Sternik,

Jany

et al. 2023

Beilstein J. Nanotechnol.

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In recent years, nanostructures with hexagonal polytypes of gold have been synthesised, opening new possibilities in nanoscience and nanotechnology. As bulk gold crystallizes in the fcc phase, surface effects can play an important role in stabilizing hexagonal gold nanostructures. Here, we investigate several heterostructures with Ge substrates, including the fcc and hcp phases of gold that have been observed experimentally. We determine and discuss their interfacial energies and optimized atomic arrangements, comparing the theory results with available experimental data. Our DFT calculations for the Au-fcc(011)/Ge(001) junction show how the presence of defects in the interface layer can help to stabilize the atomic pattern, consistent with microscopic images. Although the Au-hcp/Ge interface is characterized by a similar interface energy, it reveals large atomic displacements due to significant mismatch. Finally, analyzing the electronic properties, we demonstrate that Au/Ge systems have metallic character, but covalent-like bonding states between interfacial Ge and Au atoms are also present.

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“…The surface free energy (γ( T )) can be calculated as where γ 0 is the surface energy at the ground state (0 K), A is the surface area, and G slab ( T ) and G bulk ( T ) are the Gibbs free energy of the slab system and bulk system, respectively. The slab contains N formula units of the bulk unit.…”

Section: Methodsmentioning

confidence: 99%

Bromine Precursor Mediated Synthesis of Shape Controlled Cesium Bromide Nanoplatelets and Their Mechanism Study by DFT Calculation

et al. 2020

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We synthesized CsBr nanoplatelets and controlled their size and shape using HBr and tetrabutylammonium bromide (TBAB) as bromine precursors, obtaining hexagonal and rectangular plates, respectively. The phenomena were elucidated by density functional theory calculations, which indicated that the formation of the hexagonal shape was explained by comparing the relaxed surface free energy of oleate on the exposable surfaces of the CsBr plates. As the bromine precursor changed from HBr to TBAB, the formation of the rectangular shape was determined by comparing the surface free energy and attachment free energy between exposable surfaces due to its bulky surfactant tail. In addition, the TEM measurements indicated that the rectangles or hexagonal shapes are aligned precisely regardless of their size. The data mean that the large plates split into smaller plates as the temperature increases so that the nanoplatelets were formed by a topdown method in which a large plate was split by surfactants rather than through a bottom-up method in which a rectangle or a hexagon grew from smaller particles. The facts were explained by the surface chemical thermodynamics model which showed that the surface area (σ) and the crystal size decreased as the temperature increased.

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First-principles calculation of Mg/MgO interfacial free energies

Cited by 24 publications

References 58 publications

Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys

Synchrotron tomographic quantification of the influence of Zn concentration on dendritic growth in Mg-Zn alloys

Density functional theory study of Au-fcc/Ge and Au-hcp/Ge interfaces

Bromine Precursor Mediated Synthesis of Shape Controlled Cesium Bromide Nanoplatelets and Their Mechanism Study by DFT Calculation

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