Aluminum Oxide

Title: Aluminum Oxide
CAS Registry Number: 1344-28-1
Additional Names: Alumina
Molecular Formula: Al2O3
Molecular Weight: 101.96
Percent Composition: Al 52.93%, O 47.08%
Literature References: Occurs in nature as the minerals: bauxite, bayerite, boehmite, corundum, diaspore, gibbsite. Prepn and properties: Mellor's vol. V, 263-273 (1929); Gmelins, Aluminum (8th ed.) 35B, pp 7-98 (1934); Becher in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 822-823; Wagner, ibid. vol. 2 (1965) pp 1660-1663. Use as column matrix in ion chromatography: W. Buchberger, K. Winsauer, J. Chromatogr. 482, 401 (1989); in HPLC: M. T. Kelly, M. R. Smyth, J. Pharm. Biomed. Anal. 7, 1757 (1989). Clinical evaluation in hip replacement: L. Sedel et al., J. Bone Joint Surg. Br. 72-B, 658 (1990); of wear in hip replacement: L. P. Zichner, H.-G. Willert, Clin. Orthop. Relat. Res. 282, 86 (1992). Review of properties, biocompatibility and clinical use: P. Boutin et al., J. Biomed. Mater. Res. 22, 1203-1232 (1988); of biocompatibility: P. S. Christel, Clin. Orthop. Relat. Res. 282, 10-18 (1992).
Properties: Approximate characteristics of native aluminum oxide: White cryst powder. Very hard, about 8.8 on Moh's scale. An electrical insulator; electrical resistivity at 300° about 1.2 ´ 1013 ohms-cm. When heated above 800° it becomes insol in acid and specific gravity increases from 2.8 to 4.0. Insol in water. Very hygroscopic.
CAUTION: Potential symptoms of overexposure by direct contact are irritation of eyes, skin and respiratory system. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 12.
Use: As adsorbent, desiccant, abrasive; as filler for paints and varnishes; in manuf of alloys, ceramic materials, electrical insulators and resistors, dental cements, glass, steel, artificial gems; in coatings for metals, etc.; as catalyst for organic reactions. As a chromotagraphic matrix; originally called Brockmann aluminum oxide when used for this purpose. The minerals corundum (hardness = 9) and Alundum (obtained by fusing bauxite in an electric furnace) are used as abrasives and polishes; in manuf of refractories.
Aluminum Palmitate Aluminum Phosphate Aluminum Phosphide Aluminum Potassium Sulfate Aluminum Rubidium Sulfate

Aluminium oxide
Corundum-3D-balls.png
Aluminium oxide2.jpg
Identifiers
CAS number 1344-28-1 YesY
PubChem 9989226
ChemSpider 8164808 YesY
UNII LMI26O6933 YesY
RTECS number BD120000
ATC code D10AX04
Jmol-3D images Image 1
Image 2
Properties
Molecular formula Al2O3
Molar mass 101.96 g mol−1
Appearance white solid
Odor odorless
Density 3.95–4.1 g/cm3
Melting point 2,072 °C (3,762 °F; 2,345 K)[2]
Boiling point 2,977 °C (5,391 °F; 3,250 K)[3]
Solubility in water insoluble
Solubility insoluble in diethyl ether
practically insoluble in ethanol
Thermal conductivity 30 W·m−1·K−1[1]
Refractive index (nD) nω=1.768–1.772
nε=1.760–1.763
Birefringence 0.008
Structure
Crystal structure Trigonal, hR30, space group = R3c, No. 167
Coordination
geometry
octahedral
Thermochemistry
Std molar
entropy So298
50.92 J·mol−1·K−1[4]
Std enthalpy of
formation ΔfHo298
−1675.7 kJ·mol−1[4]
Hazards
MSDS External MSDS
EU classification Not listed.
NFPA 704
NFPA 704.svg
0
1
0
Flash point Non-flammable
U.S. Permissible
exposure limit (PEL)
OSHA 15 mg/m3 (Total Dust)
OSHA 5 mg/m3 (Respirable Fraction)
ACGIH/TLV 10 mg/m3
Related compounds
Other anions aluminium hydroxide
Other cations boron trioxide
gallium oxide
indium oxide
thallium oxide
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Aluminium oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium(III) oxide. It is commonly called alumina, and may also be called aloxide, aloxite, or alundum depending on particular forms or applications. It commonly occurs in its crystalline polymorphic phase α-Al2O3, in which it comprises the mineral corundum, varieties of which form the precious gems ruby and sapphire. Al2O3 is significant in its use to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.[5]