Tetragonal structure model for boehmite-derived γ-alumina -: art. no. 144110

gamma-alumina (gamma-Al2O3) derived from boehmite has historically been described as having a cubic spinel structure with Fd (3) over barm symmetry, despite reports of tetragonal distortion in the structure. Based on neutron diffraction, transmission electron microscopy, and magic angle spinning NMR data, we propose a tetragonal model for the structure of boehmite-derived gamma-Al2O3 with I4(1)/amd space group symmetry, a maximal subgroup of Fd (3) over barm. It is also demonstrated that an accurate average structural model cannot be achieved if the cations are restricted to spinel positions.