Stabilizing the metastable superhard material wurtzite boron nitride by three-dimensional networks of planar defects
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Millimetre-sized crystals of the superhard semiconductor wurtzite boron nitride (w-BN) can now be fabricated at atmospheric pressure and moderate temperatures.
As hard as a diamond and having a wide electronic band gap and high thermal conductivity, w-BN is a metastable form of BN that is attracting considerable attention for potential use in next-generation electronics.
Current methods for producing w-BN involve direct conversion of hexagonal BN (h-BN) at high pressures. However, the bulk of the material returns to its h-BN form when the pressure is released, leaving only small amounts of w-BN crystals with micrometre-sized grains.
By introducing planar defects into the crystals, a team of scientists led by researchers from the Advanced Institute for Materials Research at Tohoku University was able to delay the transformation from w-BN to h-BN and produce millimetre-sized crystals of w-BN.
- PNAS 116, 11181–11186 (2019). doi: 10.1073/pnas.1902820116