SCHEDULED MAINTENANCE
Synthesis of boron nitride nanostructures from borates of alkali and alkaline earth metals†
Abstract
Reactions of borates of alkali and alkaline earth metals with ammonia in a temperature range of 950–1250 °C are explored with respect to the nano-boron nitride syntheses. M2O(MO)·nB2O3 borates, where M2 = Li, Na, K, and M = Mg, Ca, Sr, Ba are studied for a molar ratio n = 0.5–5.0. It is found that various boron nitride (BN) nanostructures such as BN-nanotubes (BNNTs), graphene-like BN petals (BNGPs), and columnar porous BN (BNP) flakes grow depending on the borate composition and synthesis temperature. Both morphology and yield of BN-nanostructures depend on the basicity of the metal oxide and its fraction in the precursor borate. Borates of Li, Mg, and Ca demonstrate the highest ability to produce BNNTs. Borates of Na and K produce BNGPs in the whole range of investigated n values and temperatures. BNP flakes with pores of 10–100 nm are formed from Mg-borates with n > 3.
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