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| Al2O3 | |
|---|---|
| Name | Aluminium oxide |
| Formula | Al2O3 |
| Molar mass | 101.96 g·mol−1 |
| Appearance | white crystalline powder |
| Density | 3.95–4.1 g·cm−3 |
| Melting point | 2072 °C |
| Boiling point | 2977 °C |
Al2O3 is a chemical compound of aluminium and oxygen that forms a hard, refractory oxide widely studied across materials science, chemistry, and engineering. It appears naturally as several mineral polymorphs and is central to technologies from metallurgy to electronics; its study intersects historical developments involving James Watt, Marie Curie, Thomas Edison, Louis Pasteur, and institutions such as Royal Society, Max Planck Society, and Massachusetts Institute of Technology.
The compound crystallizes in multiple polymorphs including corundum, γ-, δ-, θ- and β- phases; the corundum structure relates to lattice concepts explored by William Henry Bragg, William Lawrence Bragg, Linus Pauling, Max von Laue, and Ernst Ruska. Its hexagonal close-packed oxygen lattice and octahedral aluminium coordination are discussed in work associated with Niels Bohr, Arnold Sommerfeld, Werner Heisenberg, Paul Dirac, and Erwin Schrödinger. Surface and defect chemistry have been probed using techniques developed at Argonne National Laboratory, Lawrence Berkeley National Laboratory, CERN, Bell Labs, and IBM Research.
Naturally occurring corundum manifests as gem varieties ruby and sapphire mined in regions linked historically to Mogok, Sri Lanka, Kashmir, Myanmar, and Madagascar. Large-scale production follows Bayer process developments with industrial scale-up by companies like Alcoa, Rio Tinto, Rusal, BHP, and facilities influenced by standards from International Organization for Standardization, American Society for Testing and Materials, and European Committee for Standardization. Historical mining and trade touch on events involving British East India Company, Dutch East India Company, Ottoman Empire, Mughal Empire, and Qing dynasty.
Aluminium oxide is refractory and electrically insulating, exhibiting high thermal conductivity and chemical inertness; these properties are measured using methods from National Institute of Standards and Technology, Fraunhofer Society, Los Alamos National Laboratory, Oak Ridge National Laboratory, and National Physical Laboratory (United Kingdom). Its amphoteric behavior—reacting with acids like protocols used by Dmitri Mendeleev and bases in alkaline fluxes—was characterized alongside studies by Robert Bunsen, Gustav Kirchhoff, Antoine Lavoisier, John Dalton, and Amedeo Avogadro.
Aluminium oxide is pivotal as an abrasive in products by firms such as 3M, Stanley Black & Decker, Norton Abrasives, and Saint-Gobain; in refractory linings for blast furnaces associated with historical developments at Bethlehem Steel and US Steel; as a catalyst support in processes developed by Fritz Haber, Carl Bosch, Ronald Breslow, and industrial units at ExxonMobil, BASF, Shell plc, and Dow Chemical Company. In electronics it serves as substrates and dielectrics in devices influenced by innovations at Intel, Samsung Electronics, TSMC, Texas Instruments, and Qualcomm; in medical implants it has been studied in clinical trials at Mayo Clinic, Cleveland Clinic, Johns Hopkins Hospital, Karolinska Institute, and Massachusetts General Hospital.
Commercial production typically uses the Bayer process converting bauxite ores processed by engineers from Alcoa and refiners following process patents and improvements referenced by George B. Kistiakowsky and chemical engineers trained at Imperial College London, ETH Zurich, University of Cambridge, University of Oxford, and California Institute of Technology. Laboratory syntheses include sol–gel routes and chemical vapor deposition methods developed and optimized in research groups at MIT, Stanford University, University of California, Berkeley, Princeton University, and Harvard University.
As a fine particulate, aluminium oxide dust management follows occupational guidelines from Occupational Safety and Health Administration, National Institute for Occupational Safety and Health, World Health Organization, European Agency for Safety and Health at Work, and International Labour Organization. Disposal and environmental impact assessments reference analyses from United Nations Environment Programme, Environmental Protection Agency, Greenpeace, World Wide Fund for Nature, and academic studies led by Yale University, Columbia University, and University of Cambridge.
The corundum (α) phase belongs to space group R-3c with lattice parameters measured and cataloged by crystallographers associated with International Union of Crystallography, American Crystallographic Association, Cambridge Crystallographic Data Centre, Deutsches Elektronen-Synchrotron, and European Synchrotron Radiation Facility. High-pressure and high-temperature transitions among metastable forms were explored in experiments at Lawrence Livermore National Laboratory, GSI Helmholtz Centre for Heavy Ion Research, The University of Tokyo, Australian National University, and Pohang Accelerator Laboratory.
Category:Aluminium compounds Category:Oxides