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  Synthesis of long CNTs


Synthesizing apparatus for CNTs

The diameter of CNTs is several nanometers, but its length varies greatly from several micrometers to several millimeters depending on its synthesize method. It is necessary to compose longer CNTs in large quantities to make use of its mechanical strength and high thermal conductivity to the big materials such as architectural materials.

There are several methods to synthesize CNTs. The chemical vapor deposition (CVD) is one of those methods and very suitable for long and a large quantity CNT synthesis. Therefore we use a radical CVD apparatus that is revamped chemical vapor deposition apparatus (CVD). In this device, a plasma ball is generated on the antenna tip above the catalyst substrate and decomposes source gases to synthesize CNTs on that substrate. The distance between the substrate and the plasma ball prevents catalyst from damaging by the plasma and prolongs catalyst lifetime. That enables us to compose long CNTs.


The radical CVD apparatus (left figure) and its diagrammatic illustration (right figure)

Long CNTs

It is possible to synthesize several millimeter long CNTs by using the radical CVD apparatus under proper synthesis condition. The CNTs at the SEM image below are about 5 millimeter long. That is one of the longest CNTs in the world. It is expected that these long CNTs can make several new materials or devices possible.


The SEM image of about 5 mm long CNTs



[1] T. Iwasaki, J. Robertson, H. Kawarada, "Mechanism Analysis of Interrupted Growth of Single-Walled Carbon Nanotube Arrays", Nano. Lett., 8, 886-890 (2008)