Effect of catalyst content on morphology and productivity of boron nitride nanotubes synthesized by ball milling and annealing method

Abstract

Boron nitride nanotubes were prepared by ball milling and annealing method using boron oxide and ammonia as raw materials and iron or magnesium powder as catalyst. The effect of iron or magnesium content on morphology and yield of boron nitride nanotubes was studied. The results show that uniform fine boron nitride nanotubes can be obtained by annealing process when the precursor of boron oxide does not contain catalyst, but the yield is very low. Appropriate iron can play a good catalytic role, a large number of boron nitride nanotubes with uniform size can be obtained. With the increase of iron content, the productivity of the product decreases and the morphology of the annealed products changes from boron nitride nanotubes with uniform size to boron nitride nanotubes with uneven diameter and length. When the molar ratio of boron oxide and iron content reaches 1∶1, the productivity of the product increases and the morphology of them changes from smooth boron nitride nanotubes to coral-like boron nitride micro-nanostructures with a large number of boron nitride nanosheets growing vertically on the surface of boron nitride nanotubes, and the diameter of the product increases obviously. The change of magnesium content only affects the size, uniformity and productivity of the product, no effect on morphology was observed. Changes in morphology and yield of boron nitride nanotubes can be explained by gas-liquid-solid growth mechanism.

Keywords

• content of catalyst
• boron nitride nanotube
• coral-like boron nitride micro-nano structure
• ball milling and annealing method
• morphology
• productivity