TURNING ONIONS INTO DIAMONDS. Nano-diamonds can
be created without high pressure by squeezing carbon "onions"
(nested buckyball-like structures) with ion beams. Graphite
material can be made into diamond the hard way, with the use of
high pressure (above 10^6 atmospheres), high temperature, and
the use of catalysts. But recently scientists have been able to
bombard carbon onions with electron beams and now ion beams
as well, and have been able to convert the onions almost
completely into diamonds, up to 100 nm in size. Researchers at
the Max Planck Institute in Stuttgart (Florian Banhart,
banhart@wselix.mpi-stuttgart.mpg.de) use a beam of neon ions
to pelt the onions, which act like miniature pressure cells. With
larger ion accelerators, one should be able to make macroscopic
amounts of irradiation-induced diamond. (Experimental work:
Wesolowski et al., Applied Physics Letters, 6 Oct. 1997; theory
paper (Zaiser and Banhart) upcoming in Physical Review Letters;
figure at www.aip.org/physnews/graphics.)