What Marilyn Monroe never knew about diamonds, Israelis discover hard
diamond
Judy Siegel-Itzkovich
,found at THE
JERUSALEM POST Dec. 24, 2007
Everybody knows that diamonds are a girl's best friend, sang Marilyn Monroe,
but until chemists at Bar-Ilan University and mechanical engineers at the
Technion, Israel Institute of Technology studied them, nobody could explain the
precious gem's secret for being the hardest material in nature.
The answer to this question has been sought for years by numerous scientists
around the world.
In an article soon to be published in The Journal of Physical Chemistry by
Prof. Shmaryahu Hoz of Bar-Ilan and of the Technion in Haifa with Dr. Lior
Itzhaki, Prof. Eli Altus and Prof. Harold Basch of Bar-Ilan in Ramat Gan, the
secret behind the super-hard material will be revealed. The researchers
predicted that the discovery will lead to the development of additional
super-hard materials, some of which may be even harder than the diamond.
Gem-quality diamond in
Kimberlite. (Reproduced by permission of National
Aeronautics and Space Administration)
The authors noted that understanding the origin of materials' hardness is
required for intelligent design. Their research resulted in the discovery that
the interactions among atoms that are not chemically bonded directly to each
other are responsible for the diamond's hardness.
Hoz noted that diamonds are made from pure carbon. Every atom of carbon in a
diamond is surrounded by four additional carbon atoms directly bonded to it.
However, each of these atoms is linked to three additional carbon atoms. Thus
the resulting structure was very special, he said.
The team members, who for years have been studying the laws of mechanical
engineering in the nano-metric world, previously discovered a synthetic
molecular rod 40 times harder than diamonds and traced its hardness to its
bonding hybridization.
However, they said, this did not apply to the diamond, because the bonding
hybridization in the gem was the weakest in the realm of carbon chemistry.
Combining quantum mechanics and mechanical engineering at the nano-molecular
level, they discovered another contributor to hardness: The repulsive
interaction between two atoms not directly bonded chemically to each other.
In their research, they found that this interaction is behind the mystery and
is one of the major factors behind the diamond's super-hardness. The hardness
results from the fact that diminishing the distance between these atoms induces
an exponential rise in energy, the authors suggested.