Concentric shelled and plate-like graphitic boron nitride nanoparticles produced by CO2 laser pyrolysis

The morphology of graphitic boron nitride nanometric particles produced from the reaction between ammonia and borontrichloride heated by a CO2 laser is investigated by high resolution electron microscopy. A variety of roughly spherical particles are revealed, consisting of concentric graphitic shells and ranging in size from 20 to more than 100 nm and in shape from hollow to filled-to-the-center. This onion-like configuration is very similar to that observed in carbon materials. Another morphology made of stackings of a few perfectly flat graphitic sheets (10 to 50 layers, 50 nm in length) is developed after heat treatment.