Structural change of Ni–Cu alloy nanowires with temperature studied by in situ X-ray absorption fine structure technique

Abstract

Ni–Cu alloy nanowire array, with uniform length and diameter, was well fabricated by using alternating current electrodeposition. Both X-ray diffraction and in situ heating extended X-ray absorption fine structure technique were employed to characterize its structural change with temperature. As expected, a weak concentration fluctuation of Ni and Cu atoms was found in the as-prepared nanowires. However, this concentration fluctuation can be easily eliminated by heating the as-prepared sample at 200 °C, which resulting in an approximately homogeneous Ni–Cu solid solution. From the nanostructural point of view, the serviceability temperature of Ni–Cu alloy nanowire array in magnetism could not exceed 200 °C. The Ni–Ni, Ni–Cu and Cu–Cu bonds were found to have different thermal expansion behaviors, causing the distortion of the crystal cell. An average thermal expansion coefficient (1.1 × 10 −5 K −1) was obtained. The structural change of Ni–Cu alloy nanowires with temperature was discussed.