Making Diamonds
Chris Rieger
One of my students is interested in trying to make diamonds. He has done
some research and found one method involving passing acetone vapour and oxygen
over a silicon substrate heated to 800 degrees Celsius. Has anyone every
tried this method? Any words of wisdom? If anyone has heard of alternative
methods I would be glad to hear them. Just remember that we have access to
only the basic lab equipment available in a high school chemistry lab. Thank
you in advance!
Chris Rieger
Tomas Eriksson
My guess is that the method your student has found produces so-called
diamond-like films; a thin carbon film which has small areas of
diamond-like structure (and probably amorphous carbon between them).
This type of coating on silicon will probably not be recognized as being
related to diamond at all by most people...
* WARNING! Mixing acetone vapour and oxygen can (will) give you an
* EXPLOSIVE MIXTURE. I'd be very reluctant to deliberately mix vapour
* of a combustible organic compound and pure oxygen myself, and I would
* STRONGLY DISRECOMMEND letting a high school student do this!
I guess you all know that poor chemists die young, but I see no reason
to speed up the process. :-)
The method used on an industrial scale to produce diamonds involves very
high temperatures (somewhere 1000-2000 deg. C, I think), and extremly
high pressures. The equipment used to produce these reaction conditions
wouldn't fit into a high school chemistry lab, I'm afraid... The
starting material is graphite mixed with small amounts of various other
things, including some metal compounds which act as catalysts. I'm
afraid I don't see any way you could do this in your chemistry lab.
As an alternative to actually doing diamonds (you don't get gem quality
diamonds anyway... :-( ), if this is some kind of project, couldn't you
have the student check Scientific American and similar sources; there
should be a popular-level description of the manufacture of synthetic
diamonds somewhere (it could very well be from the 1970's and 1960's
though). Perhaps the student can contact some company which manufactures
synthetic diamonds and get some additional information them? A phase
diagram for carbon could probably be instructive to study, and perhaps
the conditions needed to produce diamonds could be contrasted with the
conditions under which the presently very fashionable carbon allotrope
buckminsterfullerene is formed?
Tomas Eriksson (tom...@physchem.kth.se)
Dept. Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden
Arno Hahma
>The method used on an industrial scale to produce diamonds involves very
>high temperatures (somewhere 1000-2000 deg. C, I think), and extremly
>high pressures. The equipment used to produce these reaction conditions
>wouldn't fit into a high school chemistry lab, I'm afraid... The
>starting material is graphite mixed with small amounts of various other
>things, including some metal compounds which act as catalysts. I'm
>afraid I don't see any way you could do this in your chemistry lab.
Then there is still one way of making diamonds in large scale, without
the need for any high tech equipment - using aromatic explosives.
Russians do it this way, they produce industrial diamonds with
explosives, several tons annually.
The procedure is simple: mix carbon black into TNT, explode the charge
and collect the resulting soot. It will contain 20..50 % by its weight
of diamonds, depending on how lucky you are ;-). There is just one
problem: how to effectively collect the soot... Strong pressure
vessels are useful.
>Tomas Eriksson (tom...@physchem.kth.se)
>Dept. Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden
ArNO
2
M. Bruce Wehr
I started reading this group not too long ago - primarily to determine if it could augment my recently begun studies in gemology.
Yes, diamonds are currently synthesized, but, other than casual knowledge, I'm not familiar with the processes. I would be interested in hearing about the method your student has found. I will try to find what I can and follow up. What little I do know about diamond synthesis leads me to beleive that the equipment needed to generate the high pressures required would not be typical of a school lab, however.
--
\ Bruce Wehr (we...@etcv01.eld.ford.com) /
*--------------\ Ford Motor Company - Electronics Division /--------------*
\ Electronics Technical Center - Powertrain Electronic Controls Engineering /
*-- 17000 Rotunda Drive, Room B360, Dearborn, MI 48121 (313)248-5530 --*
M. Bruce Wehr
> As an alternative to actually doing diamonds (you don't get gem quality
> diamonds anyway... :-( )
Though I have no formal chemistry background, I do know from my gemological studies that gem quality diamonds are synthesized regularly today. True, most don't find their way into jewelry (though they could), but enough do that jewelers have to beware. (Yes, synthetic diamonds *can* be identified as such).
Diamonds are not the only gem that is synthesized today - in fact, most well known gems are. With the right equipment, however, a synthetic gem that cannot be distinguished from its natural counterpart has yet to be made.
Laurent Fulchieri
I know it is possible making diamond from methane
at high temperature (>2300 K)and low pressure (<0.5 atm)
in a plasma reactor (arc or induction).
for more details you can contact :
G. FLAMANT
IMP du CNRS BP 5
66120 FONT ROMEU FRANCE
fax : 68 30 29 40
(no email)
======================================================
| Laurent Fulcheri |TEL : (33) 93 95 74 06 |
| Centre d Energetique | |
| Ecole des Mines de Paris |FAX : (33) 93 95 75 35 |
| Rue Claude Daunesse |========================|
| | |
| 06560 SOPHIA ANTIPOLIS | lau...@cenerg.cma.fr | |
| FRANCE | |
|=====================================================
Braswell Lance Todd
The low pressure high temperature method does indeed produce diamond films.
However, the complete mechanism is still unknown. I have several articles
on this subject at home. If anyone is interested, send me some e-mail.
Perhaps the easiest way to make these films is with an acetylene
torch directed a few cm above a Si wafer for a couple of hours.