A furnace which permitted the simultaneous application of microwave and radiant energy was used to investigate the sintering of partially stabilized material which was doped with 3mol% of yttria. The occurrence of microwave-enhanced sintering was clearly demonstrated, with densification taking place at a lower temperature when a high-frequency electric field was applied. By analyzing the variation in electric field strength as a function of furnace temperature, this enhancement was shown to be non-thermal in nature and depended upon the electric field strength and not upon the power density of the microwaves. This dependence upon the electric field was consistent with the existence of an additional driving-force term in the equation which described the diffusion of vacancies during sintering.

R.Wroe, A.T.Rowley: Journal of Materials Science, 1996, 31[8], 2019-26