Due to their unique mechanical and chemical properties BN nanostructures have gained an increasing interest for applications in many fields such as structural and biomedical materials, catalysts, renewable energy sources and others. Nevertheless, the detailed processes of BN nanostructures synthesis have not been fully investigated and understood. Our recent studies showed that various BN-nanostructures like nanoparticles, graphene-like flakes, nanotubes, and nanofibers had grown as a result of interaction of alkali and alkaline-earth metal borates with ammonia [1, 2]. It was found that morphology of nanostructures had drastically depended on borate composition and synthesis temperature.
In the present study we particularly focused on Li and Mg borate effects on nano-BN fabrication. For better understanding of BN nanostructures nucleation and growth mechanism a wide range of oxide mixture (M2O/MO) x nB2O3 compositions (n=1-20), where M is Li or Mg, was investigated. Synthesis of BN nanostructures was conducted in a horizontal resistive furnace. The processes of chemical interaction during synthesis were thoroughly studied using a thermogravimetric analysis in Ar-NH3 atmosphere. Differential thermal analysis of selected compositions in Ar atmosphere was additionally carried out. The structure, composition and morphology of synthesized nanostructures were studied by means of scanning and transmission electron microscopies, EDX-analysis and Raman spectroscopy. These studies entirely verified the previously proposed by us models of BN nanostructures nucleation and growth, and a significant influence of metal oxide content in borates on morphology and yield of synthesized BN nanostructures was established. The obtained results will play an important role in development of a scalable method for synthesis of BN nanostructures and nanostructured BN coatings.
1. A.T. Matveev, K.L. Faerstein, A.E. Steinman, A.M. Kovalskii, O.I. Lebedev, D.V. Shtansky, D. Golberg. Boron nitride nanotube growth via vapor-transport chemical vapor deposition process using LiNO3 as a promoter. Nano Research 8 (2015) 2063-2072.
2. A.T. Matveev, K.L. Firestein, A.E. Steinman, A.M. Kovalskii, I.V. Sukhorukova, O.I. Lebedev, D.V. Shtansky, D. Golberg. Synthesis of BN-nanostructures from borates of alkali and alkaline earth metals. J. Mater. Chem. A 18 (2015) 965-969.