DFT Simulations of Titanium Oxide Films on Titanium Metal
DFT Simulations of Titanium Oxide Films on Titanium Metal
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DOI：
10.1021/jp309827u
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发表时间：
2013-01-10
影响因子：
3.7
通讯作者：
Langel, Walter
中科院分区：
文献类型：
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作者：
Ohler, Bastian;Prada, Stefano;Langel, Walter
植入物中的钛表面被1.5-25 nm厚的氧化钛钝化层覆盖。在表面形成具有金红石和金红石结构的TiO 2相。为了提高对钝化初始阶段的理解，我们研究了Ti与最常见的氧化物表面金红石（110）和（100）以及金红石（101）和（001）之间的界面。基于DFT+U方法的模拟揭示了由已经向金属相移动的氧原子引起的金属诱导间隙态（MIGS）的存在。我们讨论了界面周围的结构无序及其对氧化物晶体结构的影响。计算的分离功为3.4- 4.3J/m（2），远高于Ti金属和TiO_2的表面能，导致界面能为负。电荷转移发生从金属的氧化物，似乎是较少依赖于氧化物相比厚片的厚度。我们计算了每个原子0.07电子的电荷转移，其中大部分仍然位于第一界面层。金属功函数由于钝化层的形成而改变，但Delta Phi对于金红石为正，对于金红石为负。
Titanium surfaces in implants are covered by titanium oxide passivation layers of 1.5-25 nm thickness. At the surface TiO2 phases form with anatase and rutile structures. To improve the understanding of the initial phases of passivation, we investigated the interfaces between Ti and the most common oxide surfaces rutile (110) and (100) and anatase (101) and (001). Simulations based on a DFT+U approach revealed the presence of metal induced gap states (MIGS) caused by oxygen atoms that have moved toward the metal phase. We discuss the structural disorder around the interface and its effect on the oxide crystal structure. The computed work of separation is 3.4-4.3 J/m(2) which is much higher than the surface energies of Ti metal and TiO2 and results in a negative interface energy. Charge transfer takes place from the metal to the oxide and appears to be less dependent on the oxide phase than on the thickness of the slabs. We computed a charge transfer of 0.07 e per atom, most of which remains located in the first interface layers. The metal work function changes as a consequence of the formation of the passivation layer, but Delta Phi is positive for rutile and negative for anatase.