Introduction of Nano-sized Growth Twins Diamond

In the past twenty years, the synthesis of nano materials has been a hot topic of materials field. The reason is not only to develop better materials, but also to explore new phenomenon under such a small scale.

Normally, the materials of high-strength tend to show the brittleness at room temperature, but improving its ductility can improve the processability of these strong/hard materials (especially metal compounds). The improved metal, alloy and ceramic materials have achieved about 4-5 times the strength of the corresponding coarse grain materials. The other problem of nano structural materials is their thermal stability-they will degrade at a higher temperature.

Therefore, when these materials are exposed under high temperature, the benefits of nanostructures will disappear. As a result, scientists around the world are trying to prepare a kind of of nano structure materials with high strength, good ductility and high temperature stability. Recently, Huang and others have successfully produced the first nano-sized twins diamond with high hardness and high heat stability.

Previously, scientists use the method of electrodeposition to increase the twins density of the material, so the copper alloy that is stronger than the nanometer copper is produced. But this phenomenon is limited to the material with face-centered cubic (FCC) structure. Therefore, using carbon nanoparticles to produce nano-sized twins diamond is of great significance.

The fold layer and stacking fault with high density are advantageous to the nano-sized twins diamond. Diamond with the width of 5nm can make the hardness up to 200GPa, which is almost twice nano diamond produced by other methods. The nano-sized twins diamond can still keep heat stability under high temperature of as high as 980 ℃, which is higher about 200 ℃ than natural diamond. These materials can be used for drilling and other industrial applications.

Huang and others have synthesized a tiny amount of nano-sized twins diamond with onion carbon nanoparticles under high pressure of 12-25 GPA and high temperature of 2200-2500 ℃. However, the real industrial applications require these materials with high performance and are easy to produce repeatedly. The most important thing is that factories also hope the cost of these materials can be as cheap as possible. But if these diamonds are produced on the basis of the current methods, the cost will be very expensive. We must develop some advanced technology to produce nano-sized twins diamond in the economic and feasible way.