Atomic scale mechanism of the transformation of gamma-alumina to theta-alumina.
gamma-alumina is known to transform to theta-alumina and finally to alpha-alumina upon thermal treatment with a catastrophic loss of porosity and catalytic activity. First-principles calculations were performed to investigate the atomic scale mechanism of the gamma- to theta-alumina transformation. The transformation pathways between the two different forms have been mapped out and identified as a sequence of Al cation migrations. Different possible Al migration paths may be responsible for the experimentally observed formation of domains and twins in theta-alumina. The estimated temperature dependence of the conversion rate is in excellent agreement with the experimental transformation temperature.
Cai
Shu-Hui
SH
Department of Physics, State Key Laboratory for Physical Chemistry of Solid Surface, Xiamen University, Xiamen 361005, People's Republic of China.
Rashkeev
Sergey N
SN
Pantelides
Sokrates T
ST
Sohlberg
Karl
K