New Discoveries About Hexagonal Boron Nitride

Recently, scientists have realized the controllable preparation of high-quality hexagonal boron nitride based on the Fe2B alloy system. Through rapid cooling and quenching technology combined with time-of-flight secondary ion mass spectrometry (ToF-SIMS), the analysis of Fe2B superficial layer B atoms and B atoms during the synthesis of hexagonal boron nitride The distribution law of N atoms.
 
Yuan Qinghong’s research team used first-principles calculations to study the growth mechanism of h-BN on Fe2B surface and proposed a vacancy-assisted synthesis mechanism for h-BN on Fe2B surface. Studies have found that the formation of B-N dimers causes a large number of B vacancies to be formed on the alloy surface, which greatly promotes the migration of B and N atoms. The diffusion of B and N atoms in the Fe2B substrate only needs to overcome the energy barrier of less than 1.5 eV, so that N atoms dissolve in large amounts near the catalytic surface.


 
In addition, by calculating and fitting the formation energies and Gibbs free energy of B-N clusters of different sizes, the study found that the h-BN nucleation barrier on Fe2B surface is about 2 eV.
 
Therefore, it is possible to synthesize h-BN at a relatively low temperature (700 K). The new "vacancy-assisted" growth mechanism proposed in this study solves the problem of traditional methods for synthesizing multilayer h-BN for a long time lacking catalysts with high N solubility and diffusion rate. Applications in the device field provide space.