A schematic diagram of phase format

A schematic diagram of phase formation and the densification behaviour during the CSP-CS process is presented in Fig. 10. When the yttrium nitrate solution is added to the raw Y2O3 powder and mixed, the yttrium nitrate solution hydrates the surface of the Y2O3 powder particles and rearranges them. When pressure is then applied to the mixed powders, the yttrium nitrate solution fills the voids between the particles. When the specimen is heated to 200 ℃, the H2O in the solution is volatilized and the remaining liquid phase in the voids is transformed into second phases such as Y4O(OH)9NO3 and Y(OH)3. The specimen then becomes very dense as the second phases locate in the voids between the particles. With sintering above 600 ℃, the second phases such as Y4O(OH)9NO3 and Y(OH)3 are transformed into tens of nano-meter-sized Y2O3 particles and decompose into H2O and N2O gas. The formation of fine-sized Y2O3 particles promote grain growth and densification. As a result, the fine-sized Y2O3 particles between the larger particles improve the packing density so that a dense Y2O3 is obtained at 1400℃ through CSP-CS.