Transition Al2O3 derived from thermal decomposition of AlOOH Boehmite have complex structures and to a large extent remain poorly understood. Here we report a detailed atomic level analysis of ?Al2O3 for the first time using a combination of Scanning Transmission Electron Microscopy imaging, XRD refinement, and DFT calculations. We show that the structure of ?Al2O3 represents a complex structural intergrowth from several crystallographic variants. The two main crystallographic variants, which are identified as ?1-Al2O3 and ?2-Al2O3, are fully structurally described. In addition, we also derive the energy of formation for ?1 and ?2-Al2O3 and the other relevant transition Al2O3 phases, and show how energetic degeneracy leads to structural disorder and complex intergrowths among several transition Al2O3. The results of the work have important implications for understanding thermodynamic stability and transformation processes in transition alumina.
Revised: February 25, 2015 |
Published: July 2, 2014
Citation
Kovarik L., M.E. Bowden, A. Genc, J. Szanyi, C.H. Peden, and J. Kwak. 2014.Structure of d-Alumina: Toward The Atomic Level Understanding Of Transition Alumina Phases.Journal of Physical Chemistry C 118.PNNL-SA-100238.doi:10.1021/jp500051j