High-surface-area corundum by mechanochemically induced phase transformation of boehmite

Milling corundum nanoparticles High-purity corundum (α-Al 2 O 3 ) nanoparticles could enable applications such as more stable catalyst supports or precursors for high-strength ceramics. Milling of corundum only produces micrometer-scale particles, and direct synthesis from other aluminum oxides that would be likely starting materials, such as γ-Al 2 O 3 , fails because of the high activation barrier for converting the lattice structure of these cubic close-packed oxides. Amrute et al. show that ball milling of boehmite, γ-AlOOH, created ∼13-nanometer-diameter corundum nanoparticles of high purity through a mechanically induced dehydration reaction and by the effect of milling impacts on the surface energy of the particles. Science , this issue p. 485