Facile synthesis of hexagonal boron nitride nanoplates via molten-salt-mediated magnesiothermic reduction

Abstract Highly crystallized hexagonal boron nitride (h-BN) nanoplates were synthesized at 1200 °C via a molten-salt-mediated reduction route using Na 2 B 4 O 7 , Mg powders as starting materials in a nitrogen atmosphere. The influence of synthesis temperature and salt/reactants weight ratio on the phase composition and morphology of the final products was investigated. The salt melt formed from MgCl 2 and Na 2 B 4 O 7 at test temperatures was found to have a positive effect on promoting the crystal growth. The morphology of the h-BN crystallites changed from spherical particles to two-dimensional (2D) plates when MgCl 2 was used as a crystallization medium. Many 2D h-BN nanoplates with a diameter of 200–600 nm and a thickness of less than 30 nm were generated. Strong violet–blue photoluminescence (PL) emission with a broad band ranging from 350 nm to 650 nm has been observed in the room temperature. The possible formation mechanism of h-BN nanoplates in molten salt was proposed.