The pressure is off

Boron Nitride is the second hardest material known to us and is used extensively in cutting and grinding tools. It is usually made by mixing the two elements at very high temperatures and then squeezing the mixture at high pressures of about 500,000 times our atmospheric pressure. Chinese researchers have reported a process of making boron nitride at 500C. B L Cui and his colleagues at the Shandong University have made tiny boron nitride crystals by heating a mixture of boron tribromide and lithium nitride, using benzene as a solvent. The challenge now is to make crystals, which can be used in abrasives and drilling tools ( Chemistry of Materials , Vol 13, p2457).