Ni-metallized graphite

Fig. 10. TEM picture of a Ni metal left in the capillary of a graphite tube. Contact angle of the Ni particle on graphite surface (angle between the Ni/graphite interface and the Ni free surface) is larger than 90° (measured angle is about 140°), indicating poor wetting of Ni on the inner wall of a graphite tube.

Similar to copper, the nickel formate is also converted to Ni metal when heated in 4%H2 in a balance of helium gas. This is demonstrated in the XRD pattern in Fig. 2a where a sample of nickel formate (in the absence of graphite) was heat-treated at 400°C for 10 h. One can clearly see that Ni metal is present. An interesting comparison may be made if the nickel formate sample is instead heated only in argon gas flow for 10 h at 400°C. In this case (Fig. 2b), both NiO and Ni are formed. Thus, it is important to heat-treat in a more reducing atmosphere to generate fully reduced metal. 

The XRD for the sample of Ni-metallized on graphite (4.6wt%) is provided in Fig. 2c, however the strongest peaks of Ni metal are overlapping with those peak reflections from the MAG-10 graphite. But, the X-ray diffraction in Fig. 2a revealed the Ni particles were pure nickel crystalline with a face-centered cubic (fee) structure. 

Air exposure of highly dispersed Ni on graphite affords a modified, less active catalyst (Ni-G2), owing to partial oxygenation of the metal. This catalyst allows bond selectivity in the hydrogenation of dienones in favor of the conjugated double bond ... 

Fig. 17. a TEM image showing single-walled nanotube bimdles, with encapsulated metal particles, produced by arc discharge techniques using Ni-Y/graphite mixtures scale bar 100 nm (courtesy of P.M. 

Presolar grains are foremost identified by their nonsolar isotopic composition. They are subsequently classified by the mineral phase carrying the isotopes and by the isotopic ratios of certain elements (mainly C, N, O, Si, Al, and Fe). Most abundant but the least understood are nanodiamonds. Best studied are the second most abundant SiC grains. Further phases include, in order of abundance, graphite, TiC, ZrC, MoC, RuC, FeC, Fe-Ni metal, Si3N4, corundum, spinel, hibonite, and Ti02. 

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