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Under high vacuum (~10^-7Torr), catalyst metal is melted with energetic electrons. A bias of >5 kV applied to the sample accelerates the thermionic current from the glowing tungsten filament. This procedure routinely produces an origami-like graphite shell enclosing a round metal core. This procedure works with iron, nickel and cobalt. Because surface tension is exploited to suspend the melt, shell width is limited to about 5 millimeters.

Splat cooling-a slight variation on this procedure-permits the formation of graphitic dendrites and delaminated membranes.

Optical images of curved kish graphite synthesis procedure

thermionic emission

tungsten filament

e^-

graphite

iron

current

Molten metal dissolves carbon from graphite stem.

Origami graphite (pale phase) sweeps over melt surface, frequently with a polygonal boundary.

Displaced, distorted reflection of glowing tungsten filament provides evidence of faceted graphite surface.

As melt cools, graphite continues to precipitate. Resulting internal pressure can rupture the graphite shell.

Origami formation is reversible, by re-heating. Pale origami islands are stable, indicating solid film on dark area. See dendrites page for further evidence of non-origami curved graphite.

Methods for control of graphite crystal shape:

Patterning graphite:

"pimple" erupting from origami-enveloped melt

origami islands immobilized within dark phase on melt