Formation of Nickel Oxide Nanotubes with Uniform Wall Thickness by Low‐Temperature Thermal Oxidation Through Understanding the Limiting Effect of Vacancy Diffusion and the Kirkendall Phenomenon |
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Authors: | Yi Ren Wai Kin Chim Sing Yang Chiam Jin Quan Huang Can Pi Ji Sheng Pan |
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Affiliation: | 1. NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, 117456 (Singapore);2. Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576 (Singapore);3. Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 3 Research Link, 117602 (Singapore) |
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Abstract: | In this work, the step‐wise oxidation mechanism of nickel (Ni) nanowires is elucidated. Rapid vacancy diffusion plays a significant role at low temperatures in forming heterostructures of nickel oxide (NiO) nanotubes with Ni nanowires. Subsequent investigations of Ni nanowire oxidation at higher temperatures and faster temperature ramp rates show that it is difficult to bypass this rapid vacancy diffusion stage, which affects the formation of the final structure. Therefore, it is unlikely to form solid NiO nanowires or NiO nanotubes with uniform wall thickness through the conventional annealing/oxidation process of Ni nanowires. Instead, a step‐wise oxidation process by combining low temperature oxidation with a chemical etching step is utilized to produce for the first time NiO nanotubes with uniform wall thickness from Ni nanowires. |
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Keywords: | Nickel oxide Nanotubes Thermal oxidation Kirkendall effect Vacancy diffusion |
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