Abstract
The surface energy of a solid measures the energy cost of increasing the surface area. All normal solids therefore have a positive surface energy1—if it had been negative, the solid would disintegrate. For this reason it is also generally believed that when certain ceramics can be found in a highly porous form, this is a metastable state, which will eventually sinter into the bulk solid at high temperatures. We present theoretical evidence suggesting that for θ-alumina, the surface energy is strongly dependent on the size of the crystallites, and that for some facets it is negative for thicknesses larger than ∼1 nm. This suggests a completely new picture of porous alumina in which the high-surface-area, nanocrystalline form is the thermodynamic ground state. The negative surface energy is found to be related to a particularly strongly adsorbed state of dissociated water on some alumina surfaces. We also present new experimental evidence based on infrared spectroscopy, in conjunction with X-ray diffraction and surface-area measurements, that θ-alumina has indeed very stable surface OH groups at high temperatures, and that this form of alumina does not sinter even at temperatures up to 1,300 K.
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References
Somorjai, G.A. Introduction to Surface Chemistry and Catalysis 275; 292 (Wiley, New York, 1994).
Garvle, R.C. Stabilization of the tetragonal structure in zirconia microcrystals. J. Phys. Chem. 82, 218–224 (1978).
Rande, M.R. et al. Energetics of nanocrystalline TiO2 . Proc. Natl Acad. Sci. USA 99, 6476–6481 (2002).
McHale, J.M., Auroux, A., Perrota, A.J. & Navrotsky, A. Surface energies and thermodynamics phase stability in nanocrystaline aluminas. Science 277, 788–791 (1997).
Wefers, K. & Misra, C. Oxides and Hydroxides of Aluminium (Alcoa Technical Paper No 19. (Revised), Alcoa Laboratories, 1987).
Wolverton, C. & Hass, K. Phase stability and structure of spinel-based transition aluminas. Phys. Rev. B 63, 24102 (2001).
Zhou, R.-S. & Snyder, R.T. Structures and transformation mechanisms of the η, γ and θ transition aluminas. Acta. Crystallogr. B 47, 617–630 (1991).
Mo, S.-D. & Ching, W.Y. Electronic and optical properties of θ-Al2O3 and comparison to α-Al2O3 . Phys. Rev. B 57, 15219–15228 (1998).
Verdozzi, C., Jennison, D.R., Schultz, P.A. & Sears, M.P. Sapphire (0001) Surface, clean and with d-metal overlayers. Phys. Rev. Lett. 82, 799–802 (1999).
Ruberto, C., Yourdshahyan, Y. & Lundqvist, B.I. Surface properties of metastable alumina: A comparative study of κ- and α-Al2O3 . Phys. Rev. B 67, 195412 (2003).
Hass, K.C., Schneider, W.F., Curioni, A. & Andreoni, W. The chemistry of water on alumina surfaces: Reaction dynamics from first principles. Science 282, 265–268 (1998).
Łodziana, L.Z., Nørskov, J.K. & Stoltze, P. The stability of the hydroxylated (0001) surface of α-Al2O3 . J. Chem. Phys. 118, 11179 (2003).
Digne, M., Sautet, P., Raybaud, P., Euzen, P. & Toulhoat, H. Hydroxyl groups on γ-alumina surfaces: A DFT study. J. Catalys. 211, 1–5 (2002).
Cai, S.H., Rashkeev, S.N., Pantelides, S.T. & Sohlberg, K. Atomic scale mechanism of the transformation of γ-alumina to θ-alumina. Phys. Rev. Lett. 89, 235501 (2002).
Yourdshahyan, Y. et al. Theoretical structure determination of a complex material: κ-Al2O3 . J. Am. Ceram. Soc. 82, 1365 (1999).
Tasker, P.W. The stability of ionic crystal surfaces. J. Phys. C 12, 4977–4984 (1979).
Sakashita, Y., Araki, Y. & Shimada, H. Effects of surface orientation of alumina supports on the catalytic functionality of molybdenium sulfide catalysts. Appl. Catal. A 215, 101–110 (2001).
Nortier, P., Fourre, P., Mohammed Saad, A.B., Saur, O. & Lavalley, J.C. Effects of crystallinity and morphology on the surface properties of alumina. Appl. Catal. 61, 141–160 (1990).
Beaufils, J.P. & Barbaux, J. Determination, par diffraction differentielle de neutrons, des faces cristallines exposees par des supports de catalyseurs en poudre. J. Chim. Phys. 78, 347–352 (1981).
Knözniger, H. & Ratnasamy, P. Catalytic aluminas: Surface models and characterization of surface sites. Catal. Rev. Sci. Eng. 17, 31–70 (1978).
Eng, P.J. et al. Structure of the hydrated α-Al2O3 (0001) surface. Science 288, 1029–1033 (2000).
Kitayama, M. & Gleaser, A.M. The Wulff shape of alumina: III, undoped alumina. J. Am. Ceram. Soc. 85, 611–622 (2002).
Wang, X.G., Chaka, A. & Scheffler, M. Effect of the environment on α-Al2O3 (0001) surface structures. Phys. Rev. Lett. 84, 3650–3653 (2000).
Okada, K., Nagashima, T., Kameshima, Y. & Yasumori, A. Effect of crystallite size on the thermal phase change and porous properties of Boehmite. J. Colloid Interface Sci. 248, 111–115 (2002).
Chuah, G.K., Jaenicke, S. & Xu, T.H. The effect of digestion on the surface area and porosity of alumina. Micropor. Mesopor. Mater. 37, 345–353 (2000).
Rohrer, G.S., Rohrer, C.L. & Mullins, W.W. Nucleation energy barriers for volume-conserving shape changes of crystals with nonequilibrium morphologies. J. Am. Ceram. Soc. 84, 2099–2104 (2001).
Hartford, J. Interface energy and electron structure for Fe/VN. Phys. Rev. B 61, 2221–2229 (2000).
Perdew, J.P. et al. Atoms, molecules, solids, and surfaces: Applications of the generalized gradient approximation for exchange and correlation. Phys. Rev. B 46, 6671–6687 (1992).
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Łodziana, Z., Topsøe, NY. & Nørskov, J. A negative surface energy for alumina. Nature Mater 3, 289–293 (2004). https://doi.org/10.1038/nmat1106
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DOI: https://doi.org/10.1038/nmat1106
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