• Korean Journal of Materials Research
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• v.22 no.3
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• pp.130-135
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• 2012

We present a method of graphene synthesis with high thickness uniformity using the thermal chemical vapor deposition (TCVD) technique; we demonstrate its application to a grid supporting membrane using transmission electron microscope (TEM) observation, particularly for nanomaterials that have smaller dimensions than the pitch of commercial grid mesh. Graphene was synthesized on electron-beam-evaporated Ni catalytic thin films. Methane and hydrogen gases were used as carbon feedstock and dilution gas, respectively. The effects of synthesis temperature and flow rate of feedstock on graphene structures have been investigated. The most effective condition for large area growth synthesis and high thickness uniformity was found to be $1000^{\circ}C$ and 5 sccm of methane. Among the various applications of the synthesized graphenes, their use as a supporting membrane of a TEM grid has been demonstrated; such a grid is useful for high resolution TEM imaging of nanoscale materials because it preserves the same focal plane over the whole grid mesh. After the graphene synthesis, we were able successfully to transfer the graphenes from the Ni substrates to the TEM grid without a polymeric mediator, so that we were able to preserve the clean surface of the as-synthesized graphene. Then, a drop of carbon nanotube (CNT) suspension was deposited onto the graphene-covered TEM grid. Finally, we performed high resolution TEM observation and obtained clear image of the carbon nanotubes, which were deposited on the graphene supporting membrane.

• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.218-224
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• 2001

Yttria-stabilized zirconia (YSZ) films were deposited with varying temperatures of ZrCl$_4$between 250~55$0^{\circ}C$ with YCl$_3$and the substrate at 100$0^{\circ}C$. Nanoamperes per square centimeter of the electric current were measured in the reactor during deposition and the current increased with increasing evaporation temperature of ZrCl$_4$. The zirconia nanometer size clusters were captured on the grid membrane near the substrate during the CVD process and observed by transmission electron microscopy (TEM). The deposition rate decreased with increasing evaporation temperature of ZrCl$_4$. A cauliflower-shaped structure was developed at 25$0^{\circ}C$ then gradually changed to a faceted-grain structure above 35$0^{\circ}C$. Dependence of the growth rate and the morphological evolution on the evaporation temperature of ZrCl$_4$was approached by the charged cluster model.