High-resolution transmission electron microscopic observations were made of grain boundaries, in the hexagonal phase, where adjacent grains were rotated with respect to one another about <2¯1•10> or <10•0> directions. They were shown to be free of intergranular glass; in agreement with previous work. It was deduced that the solid/solid energies of such grain boundaries in the hexagonal phase were relatively small.

High-Resolution Transmission Electron Microscopy of Grain Boundaries between Hexagonal Boron Nitride Grains in Si3N4-SiC Particulate Composites. K.M.Knowles, S.Turan: Crystal Research and Technology, 2000, 35[6-7], 751-8