Their findings were published in yesterday s Applied Physics Letters . Like the carbon in diamond, both boron and nitrogen in cBN tend to form short, strong chemical bonds, which is why they create such hard materials. So the scientists considered how they might combine all three elements. Like graphite, they are initially soft but can be compressed into harder materials. Squeezing BC2N at about 1.8 million times atmospheric pressure produces its cubic form, which pushes cubic boron nitride to third place on the list of hardest materials.
Diamonds still hold first place.