The sintering behavior of this oxide under high (100MPa) gas pressures was studied with regard to the densification rate, rate of decrease in specific surface area and narrowing rate of the pore-size distribution. At the low sintering temperature of 800C, the densification rate under high-pressure gas was similar to that at low pressures (1atm). The specific surface area decreased and the pore size distribution narrowed at a faster rate under high-pressure gas than under low-pressure gas. The results were taken to imply that high gas pressures enhanced surface diffusion.

Surface Diffusivity under High-Pressure Gas. Nanko, M., Ishizaki, K., Fujikawa, T., Kondo, Y.: Journal of the American Ceramic Society, 1995, 78[6], 1695-7