Binding of an Oxide Layer to a Metal: The Case of Ti(101虆0)/TiO2(100)

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• 作者：Linggang Zhu ; Qing-Miao Hu ; Rui Yang ; Graeme J. Ackland
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：February 16, 2012
• 年：2012
• 卷：116
• 期：6
• 页码：4224-4233
• 全文大小：548K
• 年卷期：v.116,no.6(February 16, 2012)
• ISSN：1932-7455

文摘

We study the chemical nature of the bonding of an oxide layer to the parent metal. In order to disentangle chemical effects from strain/misfit, the Ti(101虆0)/TiO₂(100) interface has been chosen. We use the density functional pseudopotential method which gives good agreement with experiment for known properties of bulk and surface Ti and TiO₂. Two geometries, a film-like model (with free surface in the structure) and a bulk-like model (with no free surface in the structure), are used to simulate the interface, in each case with different terminations of Ti and TiO₂. For the single-oxygen interfaces, the interface energies obtained using these two models agree with each other; however, for the double-oxygen ones, the relative stability is quite different. The disturbance to the electronic structure is confined within a few atomic layers of the interface. The interfacial bonding is mainly ionic, and surprisingly, there is more charge transfer from Ti to O in the interface than in the bulk. In consequence, the Ti/TiO₂ interface has stronger binding than the bulk of either material. This helps to explain why the oxide forms a stable, protective layer on Ti and Ti alloys.