Tokyo scientists grow diamonds without heat or pressure using electron beam

Scientists at the University of Tokyo have developed a novel method for synthesizing diamonds that avoids the intense heat and pressure usually necessary. 

When they prepared carbon samples and exposed them to an electron beam, they found that this process not only converted the material into diamond but also safeguarded delicate carbon compounds from damage.

This breakthrough could improve safety and analytical techniques in materials science and biology.

Typically, diamond creation involves transforming carbon under high temperatures and pressures or using gas phase precursors, neither of which demands such extreme conditions.

In this connection, Professor Eiichi Nakamura and his team used a novel technique using controlled electron irradiation on a molecule known as adamantane (C10H16).

The process of converting adamantane into diamond entails the removal of hydrogen atoms (C-H bonds) and their replacement with carbon-carbon (C-C) linkages, thereby arranging the atoms into a three-dimensional diamond lattice.

Previous research indicated that single-electron ionization could facilitate the breaking of C-H bonds, but this approach did not yield isolated solid products.

To overcome this limitation, Nakamura’s team utilized transmission electron microscopy (TEM), a technique capable of imaging materials at an atomic resolution.

They exposed tiny adamantane crystals to electron beams of 80-200 kiloelectron volts at specific temperatures between 100-296 kelvins in a vacuum for a few seconds.

This arrangement specifically allowed the team to determine the process of nanodiamond formation.

Meanwhile, the experiment revealed TEM’s potential for studying how electrons influence polymerization and restructuring. High-quality nanodiamonds, up to 10 nanometers in diameter and possessing a cubic crystal structure, were observed to form during the hydrogen evolution reaction.

Time-resolved TEM imaging demonstrated the gradual transformation of adamantane molecule chains into spherical nanodiamonds. The rate of this reaction was found to be regulated by the breaking of C-H bonds, a process that can also control reactions in other organic molecules.

Adamantane’s distinct stability for diamond growth is highlighted by the failure of other hydrocarbons to produce similar results.

The research could open fascinating questions and suggest homogeneous irradiation processes that may illustrate how diamonds form naturally in meteorites.

Additionally, this method could further help the production of quantum dots, which are vital components for quantum computing.

Nonetheless, the findings offer insights into growing diamonds without the conventional reliance on extreme heat.

This synthesis definitively illustrates that electrons do not destroy organic molecules. Instead, they enable these molecules to sustain well-defined chemical reactions. This achievement has the potential to influence future chemical transformations and the field of diamond production.