Historical Milestones Of Diamond Synthesis

Previously it was believed that diamond was never synthesized before the 20th century. However, in the light of the discovery of CVD methods for depositing diamond, it is possible that diamond could be formed in regions where the burning of hydrocarbon gas is incomplete. Minute diamond-like particles could have been made inadvertently when Cro-Magnon made wall paintings by brushing torches against a cave wall some 35 thousand years ago (DeVries, 1995). If this was the case, then diamond synthesis may have occurred before the modern man Homo sapiens first appeared in Africa approximately 150 thousand years ago. For example, Homo erectus who is known to be the first makers of fire, could have left behind nano-sized diamond-like particles within their half burnt wood more than one and half million years ago.

Modern attempts in the quest for diamond did not actually begin until after the renaissance. The two most famous historical cases for creating artificial diamonds were by Hannay and Moisson. However, their methods were not able to produce stable forms of diamond and therefore their claims for diamond making

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was long discounted by scientists. Hannay's experiments involved sealing hydrocarbons in the form of bone oil and lithium in steel tubes that were then heated until it was red-hot. Although it was discredited that he actually produced diamond, in hindsight, he could have done so by reducing the hydrocarbons with Li. It has been since demonstrated that diamonds do in fact form when CCl4 is heated at low pressures with Na.

It is also conceivable that the hydrocarbon in Hannay's experiment may have decomposed and the catalytic action of iron could have generated hydrogen. Although Hannay may have tried to make diamonds under pressure, the possibility that he accidentally deposited some crystallites via a vapor deposition route is a possibility. Some of the tiny crystals formed via Hannay's method show the unusual birefringence of natural diamond. Such characteristics resemble the modern diamonds that have been synthesized by chemical vapor deposition (CVD).

Table 4.1. Historical milestones of diamond synthesis

When

Who

How

1.5 MYA

Homo Erectus

Incomplete burning of wood in fires

35 KYA

Crog-Magnon

Painting cave walls using fire

1880

Hannay

Reduction of paraffin by Li

1904

Moisson

Exsolution of C from Fe

1905

Burton

Exsolution of C from Pb/Ca with H2O

1911

Von Bolton

Reduction of C2H2 by Na

1936

Leipunskii

P/T for exsolution of C from Fe

1952

Eversole

Thermal decomposition of CH4

1953

ASEA

High pressure synthesis with Fe

1954

Hall

High pressure synthesis with 12 metals

1968

Hibsman

Hint of using H atoms for CVDD

1970

Wentorf

Gem diamond growth

1971

Angus

CVDD by hot filament (no H2 addition)

1976

Derjaquin

CVDD by glow discharge

1981

Setaka

CVDD by microwave

1988

Hirose

CVDD by flame

1989

Norton

CVDD production by DC arc

Source: Abbreviations: MYA = million years ago, KYA = thousand years ago, CVDD = chemical vapor deposition diamond.

Source: Abbreviations: MYA = million years ago, KYA = thousand years ago, CVDD = chemical vapor deposition diamond.

On the other hand, Moisson could not have possibly made diamond using his method of quenching molten iron. Even if he did, the diamond formed would have completely converted to amorphous carbon by the catalytic action of molten iron at high temperature.

The historical milestones in diamond synthesis are listed in Table 4.1. Of particular importance is the discovery of catalysts, notably iron for high pressure synthesis and hydrogen atoms for CVD deposition.

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