On the way to mass-scale production of perfect bulk diamonds

Diamonds are hard. Humans have known that for ages. This hardness encompasses not only mechanical hardness, but also chemical, electrical, optical, and structural hardness (1). Diamonds are hard to cut, and shaping them requires a complex technology. Diamonds are chemically inert and, because of this, they are not processed chemically. Diamonds are resistant to electrical fields and, as an electronic material, they can work in the highest electric fields that solids can withstand. They are hard structurally and, because of this, they do not allow diffusion, they are immune to radiation, and they possess a stable defect structure. This hardness is a blessing when making “diamonds forever,” but it turns into a real curse when considered from the technological viewpoint. However, there is one physical parameter against which diamonds are not hard—temperature. Notwithstanding their many hardnesses, diamonds are a metastable solid and this metastability makes diamonds transform into graphite at high temperatures. This graphitization temperature ranges from 1,650 to 1,750 °C (2, 3) at normal pressure and may be as high as 3,000 °C at a pressure of 50 kbar. Ironically, this only weakness makes diamonds an even more difficult material technologically because it does …