Nitriding of iron boride to hexagonal boron nitride

A process for preparing hexagonal boron nitride (h-BN) from iron boride (FeB) has been described for the first time. FeB powder was nitrided in ammonia at 700 K for 24 hours yielding non-crystalline BN and -Fe₂N. Subsequent annealing in ammonia for 1 hour at 1273 K resulted in a mixture of crystalline h-BN together with -Fe, -Fe₃N and -Fe₄N. The morphology of the product grains is described. This comprises an iron nitride core loosely encapsulated in a foliated BN layer. The open nature of the product layer may account for the relatively low temperature (700 K) required for the nitriding reaction. These iron containing phases were removed with dilute mineral acid leaving h-BN and trace amounts of FeB₄₉.