Diffusion of aluminium in MgO from first principles
Diffusion of aluminium in MgO from first principles
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从第一原理看铝在氧化镁中的扩散
DOI：
10.1007/s00269-012-0506-z
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发表时间：
2012
影响因子：
1.4
通讯作者：
D. Dobson
中科院分区：
文献类型：
--
作者：
M. Ammann;J. Brodholt;D. Dobson
我们从第一性原理计算了在与行星深部内部相关的压力下，铝在方镁石（MgO）中的扩散率。通过找到铝原子迁移的一个更低能量的鞍点，我们调和了实验迁移焓与先前理论研究所得结果之间的差异。先前的研究没有认识到鞍点处的分支情况。我们还解释了铝与镁空位的实验结合焓和理论结合焓之间的差异。我们发现结合焓随着铝浓度的降低而持续增加，因此实验和理论结合能之间的差异可归因于浓度的不同。我们还发现，随着介电常数的降低，结合能随着压力的增加而增加。因此，铝不仅导致非本征空位的形成，还会结合其中一些空位，有效地减少了可用于镁扩散的空位。我们讨论了其他3 + 离子如何影响氧化物和硅酸盐中扩散的相关影响。
We have calculated the diffusivity of aluminium in periclase, MgO, under pressures relevant to deep planetary interiors from first principles. We reconcile differences between experimental migration enthalpies and those obtained with previous theoretical studies by finding a lower energy saddle point for the aluminium atom migration. Previous studies did not recognise a bifurcation at the saddle point. We also explain differences between experimental and theoretical binding enthalpies of an aluminium with a magnesium vacancy. We find that binding enthalpies continuously increase with decreasing aluminium concentrations, such that the difference between experimental and theoretical binding energies can be attributed to differing concentrations. We also find that binding energies increase with pressure as the permittivity decreases. Aluminium therefore not only causes extrinsic vacancy formation but also binds some of them, effectively removing them for magnesium diffusion. We discuss the implications for how other 3+ ions affect diffusion in oxides and silicates.
影响因子：
6.3
作者：
Alfe, Dario
通讯作者：
Alfe, Dario