High-power 28 GHz millimeter-wave radiation was applied to the fabrication
of bulk AlN, Si3N4 and Al2O3. Millimeter-wave radiation enables the rapid s
intering of these ceramics at a temperature from 50 degreesC to 300 degrees
C lower than that of the conventional method. The rapid sintering is attrib
uted to the enhancement of atomic migration due to the "nonthermal effect"
of the millimeter wave. It is indicated that millimeter wave radiation can
be used for the efficient fabrication of bulk ceramics.