A PBC analysis of beta-Si3N4 has been carried out by computer calculat
ions taking into account the atom positions for F-face identification
and bond lengths as a measure of bonding energy for face prominence. A
rod-like habit with the prism {100} and the pyramids {101} and {101BA
R} has been theoretically deduced, which can be observed on crystals g
rown under a reducing atmosphere. In the presence of oxides, preferabl
y silica, (001) and (001BAR), which are of K-type, dominate over {101}
and {101BAR}. This is attributed to face specific adsorption. The gro
wth rate anisotropy between {100} and (001) and (001BAR) faces can be
explained by a model derived from the crystal structure according to t
he growth theory of Kossel and Stranski. Conclusions are drawn concern
ing interface roughness and aspect ratio development.