Crystal structure evolution and solid solution mechanism of Al2O3-Cr2O3 system under different reaction conditions.

The (Al 1-x Cr x) 2 O 3 solid solution (ACS) is expected to be an low pollution chromium source for high-performance alumina-chromium oxide refractory materials. In this work, the effects of Cr 2 O 3 content and reaction conditions on the solid solution behavior in the Al 2 O 3 -Cr 2 O 3 system were explored and the mechanism was revealed. The relationship between the lattice parameters of the formed ACS phase and the content of Cr 2 O 3 was closer to a linear one as the temperature rose, serving as an indicator for a higher degree of reaction. The solid solution reaction between Al 2 O 3 and Cr 2 O 3 was governed by the diffusion processes of Al3+ and Cr3+ at 1300–1500 °C and 1200 °C, respectively, and thus the increase of Cr 2 O 3 content slowed the solid solution reaction at a low temperature whereas promoted it at elevated temperatures. The diffusion process of solid solution reaction within the Al 2 O 3 -Cr 2 O 3 system was consistent with the Cater model; The diffusion activation energy (E a) decreased as the content of Cr 2 O 3 increased at 1300–1500 °C. When the content of Cr 2 O 3 increased from 25 to 60 mol%, the diffusion activation energy decreased from 92.48 to 86.49 kJ/mol−1, which was attributed to the augmentation in the diffusion rate of Cr3+ caused by the increase of Cr 2 O 3 content and its vapor-phase transport mechanism at high temperatures. [ABSTRACT FROM AUTHOR]