Simulations were made of amorphous Si3N4 containing boron (Si-B-N). Short-range atomic arrangements and self-diffusion constants for amorphous Si-B-N systems having various boron contents were examined. The simulations showed that boron atoms were threefold coordinated by nitrogen atoms and that nitrogen atoms were bonded to both silicon and boron atoms in the amorphous network of Si-B-N. Also, the self-diffusion constant of nitrogen in Si-B-N was much decreased when compared with that in amorphous Si3N4. It was suggested that boron was important in decreasing the mobility of atoms in amorphous Si-B-N, and could explain the experimentally observed improved thermal stability of amorphous Si-B-N, relative to amorphous Si3N4.

Molecular Dynamics Study of Atomic Structure and Diffusion Behavior in Amorphous Silicon Nitride Containing Boron. Matsunaga, K., Iwamoto, Y.: Journal of the American Ceramic Society, 2001, 84[10], 2213-9, See also: Materials Transactions, 2002, 43[7], 1506-11