The smallest diamonds, with a width of only a few nanometers, are widely used in sensors and
Scientists report cultivation methodultra-homogeneous nanodiamonds without the use of explosives. The second advantage of the new method is the addition of useful monatomic defects to otherwise ideal diamonds.
“It is surprising that although diamond is chemically quitesimple - it's one element, carbon - it's extremely difficult to fabricate this material at the nanometer scale," says Hao Yang, the project's principal investigator.
Carbon becomes diamond when the atoms of thiselements line up in a rigid three-dimensional cubic pattern under conditions of high pressure and high temperature. Researchers have previously created nanodiamonds in the lab by detonating an explosive such as trinitrotoluene in a sealed stainless steel container. The explosion turns the carbon in the explosive material into tiny diamond particles. However, this method is difficult to control, the researchers explain. In addition, the resulting crystals are not uniform in size, requiring extra steps to sort them.
In order to develop a more accurate way to produce nanodiamonds, the scientists studied the "chemistry" used by thenature.
"We realized that the places where diamonds form in the Earth's mantle containa lot of iron and iron-carbon compounds, including carbides and carbonates," saysYang.
And when iron carbide reacts with iron oxide between the crust and the upper mantle, diamonds grow.
Armed with this knowledge, scientists have developed a chemical process to mimic the lithospheric environment beneath the Earth's surface.To do this, they created iron carbide nanoparticles of uniform size as a carbon source for diamonds.The particles were then placed in a high-pressure, high-temperature environment, similar to those found in places where natural diamonds are formed.The compounds reacted, and the result was very homogeneous nanodiamonds.
The new method allows you to create crystals with a widthonly 2 nm with differences between them less than a nanometer. Previously, such results have not been obtained. The scientists claim that this is an order of magnitude better than anyone can do without additional post-synthetic processing or purification steps.
Creating homogeneous, perfect nanodiamonds is a good thing in itself, they believeresearchers, but these materials can be even more useful when they have defects, such as empty spaces in the structure of a diamond.These voids can be replaced with atoms of carbon, nitrogen, silicon, nickel, or another element.Embedded non-carbon atoms lightly color the material, they are called "color centers".
Traditionally for diamond bombardment andEmbedding these elements into the crystal structure uses a high-energy beam of atoms such as nitrogen or silicon. However, this method cannot control how many color centers are added to a single diamond, requiring post-processing steps to produce crystals with a one-atom defect. The scientists believe that with the new method, they could develop a way to replace just one of the thousands of carbons present in a nanodiamond. Nanoparticles with only one color center are highly desirable as they can securely store information in quantum computers and telecommunications devices.
“Now we have the perfect platform fordevelopment of a method for manufacturing a single-color central nanodiamond, which is a breakthrough for a number of technologies related to diamonds. But also, in a broader sense, it would be a fascinating demonstration of how you can control one atom in a much larger structure,” Yang says.
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