Synthesis and magnetic property of boron nitride nanoparticles

Abstract

Boron nitride（BN）nanocapsules encaging Fe or Co nanoparticles were synthesized by using Fe₄N/B or Co（NH₃）₆Cl₃/KBH₄ powders as raw materials, respectively. The Fe₄N was reduced to a-Fe during annealing at 1000 ℃ for several hours with flowing 100 sccm N2 gas, and the reaction was predicted by Ellingham diagram. Co nanoparticles with BN layers were also produced by annealing the powders at 1000 ℃ in nitrogen atmosphere. These BN nanocapsules with magnetic nanoparticles exhibited soft magnetic characteristics and good oxidation resistance.

BN nanotubes, nanohorns and nanocoils were also synthesized by annealing Fe₄N and B powders. Especially, Fe-filled BN nanotubes, bamboo-type and cup-stacked type BN nanotubes were produced. Formation mechanism and nanostructures were investigated by high-resolution electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, electron diffraction, energy dispersive X-ray spectroscopy and molecular mechanics calculations.