Open Access Nano Express

High temperature in-situ observations of multi-segmented metal nanowires encapsulated within carbon nanotubes by in-situ filling technique

Yasuhiko Hayashi1*, Tomoharu Tokunaga2, Toru Iijima1, Takuya Iwata1, Golap Kalita1, Masaki Tanemura1, Katsuhiro Sasaki2 and Kotaro Kuroda2

Author Affiliations

1 Department of Frontier Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan

2 Department of Quantum Engineering, Nagoya University, Furo-cho Chikusa-ku, Nagoya, 464-8601, Japan

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Nanoscale Research Letters 2012, 7:448  doi:10.1186/1556-276X-7-448

Published: 8 August 2012

Abstract

Multi-segmented one-dimensional metal nanowires were encapsulated within carbon nanotubes (CNTs) through in-situ filling technique during plasma-enhanced chemical vapor deposition process. Transmission electron microscopy (TEM) and environmental TEM were employed to characterize the as-prepared sample at room temperature and high temperature. The selected area electron diffractions revealed that the Pd4Si nanowire and face-centered-cubic Co nanowire on top of the Pd nanowire were encapsulated within the bottom and tip parts of the multiwall CNT, respectively. Although the strain-induced deformation of graphite walls was observed, the solid-state phases of Pd4Si and Co-Pd remain even at above their expected melting temperatures and up to 1,550 ± 50°C. Finally, the encapsulated metals were melted and flowed out from the tip of the CNT after 2 h at the same temperature due to the increase of internal pressure of the CNT.

Keywords:
Carbon nanotubes; in-situ filling method; Metal nanowires; Encapsulation; Transmission electron microscopy (TEM); Environmental TEM; Melting temperature