First-principles investigations of oxygen adsorption at TiNi surface and the TiO₂/TiO-TiNi interface

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• 作者：Svetlana E. Kulkova ; Alex ; er V. Bakulin ; Q.M. Hu ; Rui Yang
• 关键词：Electronic structure ; TiNi ; Oxidation ; Interface ; Defects
• 刊名：Physica B
• 出版年：2013
• 出版时间：1 October, 2013
• 年：2013
• 卷：426
• 期：Complete
• 页码：118-126
• 全文大小：4214 K

文摘

Ab-intio study of the interaction of atomic and molecular oxygen with the TiNi(1 1 0) surface was performed using the projector augmented wave method with generalized gradient approximation for the exchange-correlation functional. The oxygen adsorption energies were calculated and the preferential adsorption sites of oxygen atom on the surface were determined. Our results confirmed the formation of a Ni-rich layer at the alloy-oxide interface. Atomic and electronic structure of both TiO/TiNi(1 1 0) and TiO₂/TiNi(1 1 0) interfaces were analyzed. The formation energies (E_f) of point defects at the interfacial layers as well as in bulk TiNi, monoclinic TiO, and rutile TiO₂ were estimated. It was shown that E_f of Ti-Ni swap defect has a lower energy than that for the Ni antisites at the TiO₂(1 0 0)/TiNi(1 1 0) interface. In the case of TiO(1 0 0)/TiNi(1 1 0) interface, the formation energies of Ti-Ni swap and Ni-antisites defects are close to each other. Our results demonstrated that E_f of Ni-defect in TiO is twice less than that in TiO₂. The increase in the formation energies of defects in TiO₂ reveal the increase in diffusion barriers of Ni atoms in comparison with those in oxides with a lower oxygen content, which hampers Ni segregation.