Activated sintering of ThO2 with Al2O3 under reducing and oxidizing conditions

Abstract The effect of Al 2 O 3 as non-soluble sintering aid of coarse-grained and fine-grained ThO 2 has been explored under oxidizing and reducing atmospheres. It was found that Al 2 O 3 increases the sinterability of coarse-grained ThO 2 powder substantially under both oxidizing and reducing conditions. Sintering of fine-grained ThO 2 powder based pellets resulted in slightly lower densities upon doping with Al 2 O 3 compared to the undoped system. Precise X-ray diffraction analysis of the unit cell parameter and microprobe investigations ascertained that Al is not incorporated in the ThO 2 matrix under any of the experimental conditions. X-ray diffraction measurements on the sintered ThO 2 gave 559.74 ± 0.01 pm as the cubic unit cell parameter. It was further observed that the sintering atmosphere has a limited, but measurable effect in the late sintering stage of pure ThO 2 .