South Korean scientists have made a breakthrough in the field of diamond synthesis. They managed to grow the hardest stones in laboratory conditions in just 15 minutes at normal pressure. This method differs from traditional methods of obtaining synthetic diamonds.

A group of scientists led by physicist and chemist Rodney Ruoff from the South Korean Institute of Basic Sciences has developed a new method of diamond synthesis without the use of seed crystals and high pressure, which greatly facilitates the “growth” of stones. The scientists published their findings in the journal Nature.

It is known that natural diamonds are formed in the bowels of the earth, at a depth of tens of kilometers, under great pressure of several gigapascals and a temperature of over 1500 ° C. Similar natural conditions are used in the method currently used to synthesize 99% of all artificial diamonds. This method is called “growing at high pressure and high temperature » (HPHT) uses extraordinary parameters to convert carbon into diamond based on a small seed crystal.

However, maintaining such high pressure and temperature is a technically difficult task. Additionally, the ingredients used in the process limit the size of the resulting diamond to one cubic centimeter. HPHT also takes a lot of time; Very small stones take about two weeks to grow.

Another method, chemical vapor deposition, overcomes some of the disadvantages of HPHT, such as high pressure, but retains the need for seed crystals.

The new diamond synthesis technology proposed by Ruoff’s team allows you to get rid of the listed features of both existing methods. The method is based on the use of heated gallium with a small amount of silicon in a graphite crucible. Gallium was chosen because previous studies have shown that it can catalyze the formation of graphene from methane. The crucible was placed in a specially designed chamber in which normal atmospheric pressure (as at sea level) was maintained and through which superheated methane enriched in carbon was passed. During the course of experiments, researchers concluded that a mixture of gallium, nickel and iron together with a pinch of silicon is optimal as a catalyst for the growth of diamonds. After 15 minutes, diamonds began to appear in the form of a diamond film at the bottom of the crucible. Spectroscopic analysis showed that this film was highly transparent with a small amount of silicon atom impurities.

The exact mechanism of diamond formation in this method has not yet been elucidated. Presumably temperature affects the movement of carbon towards the center of the crucible, where it crystallizes and forms a diamond structure.

It is stated that the new method has disadvantages. One problem is that diamonds produced this way are very small; It is hundreds of thousands of times smaller than diamonds grown using the HPHT method. Therefore, they cannot be used as wearable jewelry. The potential of these diamonds to be used for technological purposes such as polishing and drilling is still controversial. But because the process occurs at low pressure, it could significantly increase diamond synthesis, Ruoff said. In a few years the world may have a clearer idea of ​​the possible commercial application of this method.