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In Situ TEM Observation of a Microcrucible Mechanism of Nanowire Growth

Science  09 May 2014:
Vol. 344, Issue 6184, pp. 623-626
DOI: 10.1126/science.1251594

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Nanowire Growth Observed

In the hypothetical microcrucible growth mechanism for nanowires, a molten catalytic particle located in a pore on a substrate continually feeds the outward growth of the wire. To observe such a mechanism requires the ability to examine nanowire growth in situ. Boston et al. (p. 623) studied various stages of Y2BaCuO5 nanowire growth using transmission electron microscopy and were able to observe a microcrucible growth mechanism directly.

Abstract

The growth of metal oxide nanowires can proceed via a number of mechanisms such as screw dislocation, vapor-liquid-solid process, or seeded growth. Transmission electron microscopy (TEM) can resolve nanowires but invariably lacks the facility for direct observation of how nanowires form. We used a transmission electron microscope equipped with an in situ heating stage to follow the growth of quaternary metal oxide nanowires. Video-rate imaging revealed barium carbonate nanoparticles diffusing through a porous matrix containing copper and yttrium oxides to subsequently act as catalytic sites for the outgrowth of Y2BaCuO5 nanowires on reaching the surface. The results suggest that sites on the rough surface of the porous matrix act as microcrucibles and thus provide insights into the mechanisms that drive metal oxide nanowire growth at high temperatures.

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