Fig. 4: Topotactic phase transformation process revealed by density functional theory (DFT) calculations.
From: High-surface-area corundum nanoparticles by resistive hotspot-induced phase transformation
a The bulk energies (μ, eV per Al2O3) and the surface energies (є, eV Å–2) of representative crystal surfaces for the three Al2O3 phases. The δʹ-Al2O3 and α-Al2O3 phases are anhydrous and the γ-Al2O3 phase is hydroxylated with 2 OH nm–2. b The total energy (the sum of bulk energy and surface energy) of the Al2O3 nanocrystals of three phases as plotted against the specific surface area. c The contour plots of partial charge density at the highest bands (0.3 eV below the Fermi levels) of the anhydrous surface states of γ-Al2O3(100), δʹ-Al2O3(100), and α-Al2O3(0001) from top view (top) and lateral view (bottom).
