Oxidation of pure and K-doped NiTi shape memory surface: a DFT investigation
نویسنده
چکیده
The oxidation of Ti terminated NiTi surfaces is investigated with density functional theory. The surfaces considered are (001) and (110) of the austenite phase (B2) and (010) of the martensite phase (B19’). The favored adsorption sites for atomic oxygen are fourfold hollow on B2 (001), and twofold bridged between two surface Ti atoms on B2 (110) and B19’ (010). Adsorption of one oxygen molecule per surface Ti atom results in the formation of a rutile-like protective layer of TiO2. The oxidation results in outward and inward movement of surface Ti and Ni atoms, respectively, signaling depletion of Ni atoms from the surface region. Substitution of Ni by K near the surface is found to enhance the formation of TiO2 at the expense of TiO, and increase the stability and facilitate the growth of thicker layers of titanium oxides on the NiTi surfaces. This is of importance for the biofunctionality of the alloy. PACS numbers: 73.20.At, 68.43.Fg
منابع مشابه
Theoretical investigation of the interaction of oxygen with pure and K-doped NiTi shape memory surface alloys
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Theoretical investigation of the interaction of oxygen with pure and K-doped NiTi shape memory alloys
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