Absolute ionic diffusion in MgO—computer calculations via lattice dynamics

Vočadlo, Lidunka; Wall, A.; Parker, Stephen C.; Price, G. D.

doi:10.1016/0031-9201(94)02987-m

Cited by 44 publications

(18 citation statements)

References 16 publications

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“…These energies compare favorably with the experimental and calculated data. Examination of the pathway taken by the migrating vacancy showed that it followed a linear route between the two sites diagonally across the face of an MgO cube, which agreed with the approximately room-temperature data calculated by Vocadlo et al 8 We now apply this approach to modeling diffusion at the grain boundary. …”

Section: B Diffusion Path For Isolated Vacancies In the Bulksupporting

confidence: 85%

“…Using this method, Mackrodt and Stewart 6 calculated activation energies for vacancy migration of 2.16 eV for magnesium and 2.38 eV for oxygen in bulk MgO. More recent calculations using the SS potential 28 by Vocadlo et al 8 predicted activation energies of 1.99 eV for magnesium and 2.00 eV for oxygen. Experimental activation energies for magnesium vacancy migration are available, which include values of 2.28 eV ͑Ref.…”

Section: B Diffusion Path For Isolated Vacancies In the Bulkmentioning

confidence: 99%

“…7͒, which indicated that the defect formation volume is important and highly dependent on pressure. More recently, Vocadlo et al 8 calculated the activation energies for self-diffusion in MgO as a function of temperature indicating that the energies decreased with increasing temperature while the migration volume increased. These studies have all considered bulk MgO and yet the polycrystalline nature of many materials means that grain boundaries should be considered.…”

Section: Introductionmentioning

confidence: 99%

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Vacancy migration at the {410}/[001] symmetric tilt grain boundary of MgO: An atomistic simulation study

1997

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We present the results of atomistic simulations to evaluate diffusion pathways and hence activation energies for cation and anion vacancy migration in the MgO ͕410͖/͓001͔ symmetric tilt grain boundary, which can be considered as a series of dislocation pipes. The approach employed in this study is based on molecular dynamics and we found that the diffusion routes were anisotropic with diffusion down the dislocation pipes favored over diffusion between the pipes. The lowest calculated activation energies for isolated vacancies were 1.05 eV for magnesium and 1.01 eV for oxygen at 0 GPa ͑cf. bulk activation energies of 1.94 eV for magnesium and 2.12 eV for oxygen͒. The lower activation energies coupled with the enhanced defect concentrations at the interface shows that boundaries are regions of high diffusivity. However, the concentration of vacancy pairs at the interface and the high binding energy of a magnesium-oxygen pair leads to the prediction that a large component of the defects is bound, which in turn causes the activation energy for vacancy migration to approach that of the bulk. In this case the higher boundary diffusivities are the result of high defect concentrations at the boundary.

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Section: B Diffusion Path For Isolated Vacancies In the Bulksupporting

confidence: 85%

Section: B Diffusion Path For Isolated Vacancies In the Bulkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Vacancy migration at the {410}/[001] symmetric tilt grain boundary of MgO: An atomistic simulation study

1997

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“…[42] The rate of O 2À diffusion is much lower than that of Mg 2þ . [43] Studies on thin films have also shown that SrO layer forms on top of MgO due to Sr out diffusion. [44] It is therefore likely that Sr out diffuses faster than the other species and exhibits enhanced oxidizing on the top surface.…”

Section: Sr Diffusivity May Be Higher Than That Of Mg and O Transportmentioning

confidence: 99%

High Temperature Oxidation Behavior of Hypoeutectic Mg–Sr Binary Alloys: The Role of the Two‐Phase Microstructure and the Surface Activity of Sr

2014

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The high temperature oxidation behavior of Mg-Sr hypoeutectic alloys was investigated. The oxide layer was characterized after isothermal heating experiments that were conducted at 500°C in dry airflow for 12 h. It was seen that a non-uniform oxide scale formed on hypoeutectic Mg-Sr alloys with a two-phase structure whereby the oxide over the interdendritic intermetallic phase had a finer grain size than the oxide over the a-Mg dendrites. The interrupted tests on selected alloys showed that the two phases exhibit different oxidation sequences of Sr and Mg. It was observed that the intermetallic phase oxidizes first with the formation of both MgO and SrO on the surface. The oxidation proceeds with SrO and MgO formation on the a-Mg. This sequence is different from what is predicted as possible via thermodynamic calculations based on the activities of the elements on the two-phases. SEM/EDS analyses revealed that the Sr surface-enrichment has occurred, which explains the differences between the observation and the assessment. Thermodynamic re-assessment suggested that the Sr enrichment on the surface due to the surface activity of Sr in Mg could largely determine the initial oxidation sequence.

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“…Consequently, it becomes possible to calculate a very wide range of physical properties, such as the structural, dynamical, thermodynamic, and transport properties of solids, liquids and vapors for a given interaction model. The application of atomistic simulation in minerals has achieved great success, in the fields of predicting the elastic constants of MgSiO 3 -perovskite [5], calculating the heat capacity and entropy of the major phase in the mantle [6], predicting the high pressure phase transition in simple oxides such as Al 2 O 3 at high pressure [7], and analyzing the diffusion mechanisms in a variety of oxides and silicates [8,9]. The important progresses in this field have been achieved with the development of first-principle methods [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Study of high-pressure and high-temperature behaviors and α-to-β phase transition of forsterite by first-principles and quasi-harmonic Debye model

Liu

Zhao

et al. 2008

Computer Physics Communications

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Absolute ionic diffusion in MgO—computer calculations via lattice dynamics

Cited by 44 publications

References 16 publications

Vacancy migration at the {410}/[001] symmetric tilt grain boundary of MgO: An atomistic simulation study

Vacancy migration at the {410}/[001] symmetric tilt grain boundary of MgO: An atomistic simulation study

High Temperature Oxidation Behavior of Hypoeutectic Mg–Sr Binary Alloys: The Role of the Two‐Phase Microstructure and the Surface Activity of Sr

Study of high-pressure and high-temperature behaviors and α-to-β phase transition of forsterite by first-principles and quasi-harmonic Debye model

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