The computer study of boehmite symmetry transformation barrier

• 1、Materials Science and Engineering School, Shanghai University, Shanghai 201900

Abstract： Boehmite (γ-AlOOH) has layered crystal structure that consists of alternating Al-O layers and hydrogen-bond layers. Currently characterization techniques based on diffractions could determine positions of Al and O atoms, but failed to determine H atoms' positions, leaving the probable overall crystal structure to be conjectured. We study the thermodynamic stability of probable crystal structures of boehmite using first-principles calculations, and further study energy barrier for structural transitions using transition-state theory calculations. Our results show that the two crystal structures have nearly the same thermodynamic stability, and can readily transform into each other, because the energy barrier of structural transition is 2~4 times of enegy in thermal fluctuations in the temperature range from room temperature to boehmite's dehydration temperature. The result sheds light on improving structural characterization techniques for boehmite and silimar materials, as well as on studying the transfer of hydrogen atoms in the hydrogen-bond layers.

Keywords： Materialogy；boehmite energy barrier of structural transition hydrogen bond first-principles calculation nudget elastic band method