Aluminium oxide

Aluminium oxide
(Aluminum oxide)

Identifiers
CAS Number	1344-28-1 Y
3D model (Jmol)	Interactive image Interactive image
ChemSpider	8164808 Y
ECHA InfoCard	100.014.265
PubChem	9989226
RTECS number	BD120000
UNII	LMI26O6933 Y
InChI InChI=1S/2Al.3O/q2*+3;3*-2 Y Key: PNEYBMLMFCGWSK-UHFFFAOYSA-N Y InChI=1/2Al.3O/q2*+3;3*-2 Key: PNEYBMLMFCGWSK-UHFFFAOYAC
SMILES [Al+3].[Al+3].[O-2].[O-2].[O-2] [O-2].[O-2].[O-2].[Al+3].[Al+3]
Properties
Chemical 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)
Boiling point	2,977 °C (5,391 °F; 3,250 K)
Solubility in water	insoluble
Solubility	insoluble in diethyl ether practically insoluble in ethanol
Magnetic susceptibility (χ)	-37.0·10−6 cm3/mol
Thermal conductivity	30 W·m−1·K−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
Lattice constant	a = 478.5 pm, c = 1299.1 pm
Coordination geometry	octahedral
Thermochemistry
Std molar entropy (So298)	50.92 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−1675.7 kJ·mol−1
Pharmacology
ATC code	D10AX04 (WHO)
Hazards
Safety data sheet	See: data page
EU classification (DSD)	Not listed.
NFPA 704	0 1 0
Flash point	Non-flammable
US health exposure limits (NIOSH):
PEL (Permissible)	OSHA 15 mg/m3 (Total Dust) OSHA 5 mg/m3 (Respirable Fraction) ACGIH/TLV 10 mg/m3
REL (Recommended)	none
IDLH (Immediate danger)	N.D.
Related compounds
Other anions	aluminium hydroxide
Other cations	boron trioxide gallium oxide indium oxide thallium oxide
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Aluminium oxide or Aluminum oxide (in U.S. English) 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 occurs naturally in its crystalline polymorphic phase α-Al₂O₃ as the mineral corundum, varieties of which form the precious gemstones 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.

Corundum is the most common naturally occurring crystalline form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colors to trace impurities. Rubies are given their characteristic deep red color and their laser qualities by traces of chromium. Sapphires come in different colors given by various other impurities, such as iron and titanium.

Al₂O₃ is an electrical insulator but has a relatively high thermal conductivity (30 Wm⁻¹K⁻¹) for a ceramic material. Aluminium oxide is insoluble in water. In its most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools.