Morphology and structure of BN and B4C nanocrystals

The morphology and structure of BN and B4C nanocrystals in thin layers prod uced on Si substrates by plasma-enhanced chemical vapor deposition from tri ethylamineborane were studied before and after exposure to synchrotron radi ation. The as-deposited layers consisted of two types of nanocrystals diffe ring in shape, which all had a defect diamond-like structure. After irradia tion, two types of nanocrystals were also observed, but the layers consiste d of cubic BN, hexagonal BN, and rhombohedral B4C with lattice parameters d iffering from those of bulk materials. These results were interpreted as ev idence that the irradiated layers contained "centaurs"-intergrowths of diff erent structures with coherent interfaces.