*** Welcome to piglix ***

Aluminium oxide

Aluminium oxide
(Aluminum oxide)
Corundum-3D-balls.png
Aluminium oxide2.jpg
Identifiers
1344-28-1 YesY
3D model (Jmol) Interactive image
Interactive image
ChemSpider 8164808 YesY
ECHA InfoCard 100.014.265
PubChem 9989226
RTECS number BD120000
UNII LMI26O6933 YesY
Properties
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)
insoluble
Solubility insoluble in diethyl ether
practically insoluble in ethanol
-37.0·10−6 cm3/mol
Thermal conductivity 30 W·m−1·K−1
nω=1.768–1.772
nε=1.760–1.763
Birefringence 0.008
Structure
Trigonal, hR30, space group = R3c, No. 167
a = 478.5 pm, c = 1299.1 pm
octahedral
Thermochemistry
50.92 J·mol−1·K−1
−1675.7 kJ·mol−1
Pharmacology
D10AX04 (WHO)
Hazards
Safety data sheet See: data page
Not listed.
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
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
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
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.


...
Wikipedia

...