Aluminium oxide

Last updated
Aluminium(III) oxide
(Aluminium oxide)
Corundum-3D-balls.png
Aluminium oxide A.jpg
Names
IUPAC name
Aluminium oxide
Systematic IUPAC name
Aluminium(III) oxide
Other names
Dialuminium trioxide
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.014.265 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-691-6
PubChem CID
RTECS number
  • BD120000
UNII
  • InChI=1S/2Al.3O/q2*+3;3*-2 Yes check.svgY
    Key: PNEYBMLMFCGWSK-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/2Al.3O/q2*+3;3*-2
    Key: PNEYBMLMFCGWSK-UHFFFAOYAC
  • [Al+3].[Al+3].[O-2].[O-2].[O-2]
  • [O-2].[O-2].[O-2].[Al+3].[Al+3]
Properties
Al2O3
Molar mass 101.960 g·mol−1
Appearancewhite solid
Odor odorless
Density 3.987 g/cm3
Melting point 2,072 °C (3,762 °F; 2,345 K) [1]
Boiling point 2,977 °C (5,391 °F; 3,250 K) [2]
insoluble
Solubility insoluble in all solvents
log P 0.31860 [3]
−37.0×10−6 cm3/mol
Thermal conductivity 30 W·m−1·K−1 [4]
nω = 1.768–1.772
nε = 1.760–1.763
Birefringence 0.008
Structure
Trigonal, hR30
R3c (No. 167)
a = 478.5 pm, c = 1299.1 pm
octahedral
Thermochemistry
Std molar
entropy (S⦵298)
50.92 J·mol−1·K−1 [5]
−1675.7 kJ/mol [5]
Pharmacology
D10AX04 ( WHO )
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
NFPA 704 (fire diamond)
NFPA 704.svgHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)
OSHA 15 mg/m3 (total dust)
OSHA 5 mg/m3 (respirable fraction)
ACGIH/TLV 10 mg/m3
REL (Recommended)
none [6]
IDLH (Immediate danger)
N.D. [6]
Related compounds
Other anions
aluminium hydroxide
aluminium sulfide
aluminium selenide
Other cations
boron trioxide
gallium(III) oxide
indium oxide
thallium(III) oxide
Supplementary data page
Aluminium oxide (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Aluminium oxide (or aluminium(III) 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 oxide. It is commonly called alumina and may also be called aloxide, aloxite, or alundum in various forms and 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. [7]

Contents

Natural occurrence

Corundum is the most common naturally occurring crystalline form of aluminium oxide. [8] Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colours to trace impurities. Rubies are given their characteristic deep red colour and their laser qualities by traces of chromium. Sapphires come in different colours given by various other impurities, such as iron and titanium. An extremely rare δ form occurs as the mineral deltalumite. [9] [10]

History

The field of aluminium oxide ceramics has a long history. Aluminum salts were widely used in ancient and medieval times, such as in alchemy. Several older textbooks cover the history of the field. [11] [12] A 2019 textbook by Andrew Ruys contains a detailed timeline on the history of aluminium oxide from ancient times to the 21st century. [13]

Properties

Aluminium oxide in its powdered form Oxid hlinity.PNG
Aluminium oxide in its powdered form

Al2O3 is an electrical insulator but has a relatively high thermal conductivity (30 Wm−1K−1) [4] 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. [7]

Aluminium oxide is responsible for the resistance of metallic aluminium to weathering. Metallic aluminium is very reactive with atmospheric oxygen, and a thin passivation layer of aluminium oxide (4 nm thickness) forms on any exposed aluminium surface in a matter of hundreds of picoseconds.[ better source needed ] [14] This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as aluminium bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. The aluminium oxide generated by anodising is typically amorphous, but discharge-assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline aluminium oxide in the coating, enhancing its hardness.

Aluminium oxide was taken off the United States Environmental Protection Agency's chemicals lists in 1988. Aluminium oxide is on the EPA's Toxics Release Inventory list if it is a fibrous form. [15]

Amphoteric nature

Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt.

Al2O3 + 6 HF → 2 AlF3 + 3 H2O
Al2O3 + 2 NaOH + 3 H2O → 2 NaAl(OH)4 (sodium aluminate)

Structure

Corundum from Brazil, size about 2x3 cm. Corindon azulEZ.jpg
Corundum from Brazil, size about 2×3 cm.

The most common form of crystalline aluminium oxide is known as corundum, which is the thermodynamically stable form. [16] The oxygen ions form a nearly hexagonal close-packed structure with the aluminium ions filling two-thirds of the octahedral interstices. Each Al3+ center is octahedral. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a space group of R3c (number 167 in the International Tables). The primitive cell contains two formula units of aluminium oxide.

Aluminium oxide also exists in other metastable phases, including the cubic γ and η phases, the monoclinic θ phase, the hexagonal χ phase, the orthorhombic κ phase and the δ phase that can be tetragonal or orthorhombic. [16] [17] Each has a unique crystal structure and properties. Cubic γ-Al2O3 has important technical applications. The so-called β-Al2O3 proved to be NaAl11O17. [18]

Molten aluminium oxide near the melting temperature is roughly 2/3 tetrahedral (i.e. 2/3 of the Al are surrounded by 4 oxygen neighbors), and 1/3 5-coordinated, with very little (<5%) octahedral Al-O present. [19] Around 80% of the oxygen atoms are shared among three or more Al-O polyhedra, and the majority of inter-polyhedral connections are corner-sharing, with the remaining 10–20% being edge-sharing. [19] The breakdown of octahedra upon melting is accompanied by a relatively large volume increase (~33%), the density of the liquid close to its melting point is 2.93 g/cm3. [20] The structure of molten alumina is temperature dependent and the fraction of 5- and 6-fold aluminium increases during cooling (and supercooling), at the expense of tetrahedral AlO4 units, approaching the local structural arrangements found in amorphous alumina. [21]

Production

Aluminium hydroxide minerals are the main component of bauxite, the principal ore of aluminium. A mixture of the minerals comprise bauxite ore, including gibbsite (Al(OH)3), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH)), along with impurities of iron oxides and hydroxides, quartz and clay minerals. [22] Bauxites are found in laterites. Bauxite is typically purified using the Bayer process:

Al2O3 + H2O + NaOH → NaAl(OH)4
Al(OH)3 + NaOH → NaAl(OH)4

Except for SiO2, the other components of bauxite do not dissolve in base. Upon filtering the basic mixture, Fe2O3 is removed. When the Bayer liquor is cooled, Al(OH)3 precipitates, leaving the silicates in solution.

NaAl(OH)4 → NaOH + Al(OH)3

The solid Al(OH)3 Gibbsite is then calcined (heated to over 1100 °C) to give aluminium oxide: [7]

2 Al(OH)3 → Al2O3 + 3 H2O

The product aluminium oxide tends to be multi-phase, i.e., consisting of several phases of aluminium oxide rather than solely corundum. [17] The production process can therefore be optimized to produce a tailored product. The type of phases present affects, for example, the solubility and pore structure of the aluminium oxide product which, in turn, affects the cost of aluminium production and pollution control. [17]

Applications

Known as alpha alumina in materials science, and as alundum (in fused form) or aloxite [23] in mining and ceramic communities, aluminium oxide finds wide use. Annual global production of aluminium oxide in 2015 was approximately 115 million tonnes, over 90% of which was used in the manufacture of aluminium metal. [7] The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications. Large tonnages of aluminium hydroxide, from which alumina is derived, are used in the manufacture of zeolites, coating titania pigments, and as a fire retardant/smoke suppressant.

Over 90% of aluminium oxide, termed smelter grade alumina (SGA), is consumed for the production of aluminium, usually by the Hall–Héroult process. The remainder, termed specialty alumina, is used in a wide variety of applications which take advantage of its inertness, temperature resistance and electrical resistance. [24]

Fillers

Being fairly chemically inert and white, aluminium oxide is a favored filler for plastics. Aluminium oxide is a common ingredient in sunscreen [25] and is often also present in cosmetics such as blush, lipstick, and nail polish. [26]

Glass

Many formulations of glass have aluminium oxide as an ingredient. [27] Aluminosilicate glass is a commonly used type of glass that often contains 5% to 10% alumina.

Catalysis

Aluminium oxide catalyses a variety of reactions that are useful industrially. In its largest scale application, aluminium oxide is the catalyst in the Claus process for converting hydrogen sulfide waste gases into elemental sulfur in refineries. It is also useful for dehydration of alcohols to alkenes.

Aluminium oxide serves as a catalyst support for many industrial catalysts, such as those used in hydrodesulfurization and some Ziegler–Natta polymerizations.

Gas purification

Aluminium oxide is widely used to remove water from gas streams. [28]

Abrasion

Aluminium oxide is used for its hardness and strength. Its naturally occurring form, corundum, is a 9 on the Mohs scale of mineral hardness (just below diamond). It is widely used as an abrasive, including as a much less expensive substitute for industrial diamond. Many types of sandpaper use aluminium oxide crystals. In addition, its low heat retention and low specific heat make it widely used in grinding operations, particularly cutoff tools. As the powdery abrasive mineral aloxite, it is a major component, along with silica, of the cue tip "chalk" used in billiards. Aluminium oxide powder is used in some CD/DVD polishing and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste. It is also used in microdermabrasion, both in the machine process available through dermatologists and estheticians, and as a manual dermal abrasive used according to manufacturer directions.

Paint

Aluminium oxide flakes are used in paint for reflective decorative effects, such as in the automotive or cosmetic industries.[ citation needed ]

Composite fiber

Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications (e.g., Fiber FP, Nextel 610, Nextel 720). [29] Alumina nanofibers in particular have become a research field of interest.

Armor

Some body armors utilize alumina ceramic plates, usually in combination with aramid or UHMWPE backing to achieve effectiveness against most rifle threats. Alumina ceramic armor is readily available to most civilians in jurisdictions where it is legal, but is not considered military grade. [30] It is also used to produce bullet-proof alumina glass capable to withstand impact of .50 BMG calibre rounds.

Abrasion protection

Aluminium oxide can be grown as a coating on aluminium by anodizing or by plasma electrolytic oxidation (see the "Properties" above). Both the hardness and abrasion-resistant characteristics of the coating originate from the high strength of aluminium oxide, yet the porous coating layer produced with conventional direct current anodizing procedures is within a 60–70 Rockwell hardness C range [31] which is comparable only to hardened carbon steel alloys, but considerably inferior to the hardness of natural and synthetic corundum. Instead, with plasma electrolytic oxidation, the coating is porous only on the surface oxide layer while the lower oxide layers are much more compact than with standard DC anodizing procedures and present a higher crystallinity due to the oxide layers being remelted and densified to obtain α-Al2O3 clusters with much higher coating hardness values circa 2000 Vickers hardness.[ citation needed ]

Aluminium oxide output in 2005 2005alumina.PNG
Aluminium oxide output in 2005

Alumina is used to manufacture tiles which are attached inside pulverized fuel lines and flue gas ducting on coal fired power stations to protect high wear areas. They are not suitable for areas with high impact forces as these tiles are brittle and susceptible to breakage.

Electrical insulation

Aluminium oxide is an electrical insulator used as a substrate (silicon on sapphire) for integrated circuits but also as a tunnel barrier for the fabrication of superconducting devices such as single-electron transistors, superconducting quantum interference devices (SQUIDs) and superconducting qubits.

For its application as an electrical insulator in integrated circuits, where the conformal growth of a thin film is a prerequisite and the preferred growth mode is atomic layer deposition, Al2O3 films can be prepared by the chemical exchange between trimethylaluminium (Al(CH3)3) and H2O: [32]

2 Al(CH3)3 + 3 H2O → Al2O3 + 6 CH4

H2O in the above reaction can be replaced by ozone (O3) as the active oxidant and the following reaction then takes place: [33] [34]

2 Al(CH3)3 + O3 → Al2O3 + 3 C2H6

The Al2O3 films prepared using O3 show 10–100 times lower leakage current density compared with those prepared by H2O.

Aluminium oxide, being a dielectric with relatively large band gap, is used as an insulating barrier in capacitors. [35]

Other

In lighting, translucent aluminium oxide is used in some sodium vapor lamps. [36] Aluminium oxide is also used in preparation of coating suspensions in compact fluorescent lamps.

In chemistry laboratories, aluminium oxide is a medium for chromatography, available in basic (pH 9.5), acidic (pH 4.5 when in water) and neutral formulations. Additionally, small pieces of aluminium oxide are often used as boiling chips.

Health and medical applications include it as a material in hip replacements [7] and birth control pills. [37]

It is used as a scintillator [38] and dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties.[ citation needed ]

Insulation for high-temperature furnaces is often manufactured from aluminium oxide. Sometimes the insulation has varying percentages of silica depending on the temperature rating of the material. The insulation can be made in blanket, board, brick and loose fiber forms for various application requirements.

It is also used to make spark plug insulators. [39]

Using a plasma spray process and mixed with titania, it is coated onto the braking surface of some bicycle rims to provide abrasion and wear resistance.[ citation needed ]

Most ceramic eyes on fishing rods are circular rings made from aluminium oxide.[ citation needed ]

In its finest powdered (white) form, called Diamantine, aluminium oxide is used as a superior polishing abrasive in watchmaking and clockmaking. [40]

Aluminium oxide is also used in the coating of stanchions in the motorcross and mountainbike industry. This coating is combined with molybdenumdisulfate to provide long term lubrication of the surface. [41]

See also

Related Research Articles

<span class="mw-page-title-main">Aluminium</span> Chemical element, symbol Al and atomic number 13

Aluminium is a chemical element; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals, about one-third that of steel. It has a great affinity towards oxygen, forming a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, nonmagnetic, and ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the twelfth-most common element in the universe. The radioactivity of 26Al, a more unstable isotope, leads to it being used in radiometric dating.

<span class="mw-page-title-main">Boron nitride</span> Refractory compound of boron and nitrogen with formula BN

Boron nitride is a thermally and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN. It exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form corresponding to graphite is the most stable and soft among BN polymorphs, and is therefore used as a lubricant and an additive to cosmetic products. The cubic variety analogous to diamond is called c-BN; it is softer than diamond, but its thermal and chemical stability is superior. The rare wurtzite BN modification is similar to lonsdaleite but slightly softer than the cubic form.

<span class="mw-page-title-main">Corundum</span> Oxide mineral

Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.

<span class="mw-page-title-main">Kaolinite</span> Phyllosilicate clay mineral

Kaolinite ( KAY-ə-lə-nyte, -⁠lih-; also called kaolin) is a clay mineral, with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6).

The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell. The Hall–Héroult process applied at industrial scale happens at 940–980 °C and produces 99.5–99.8% pure aluminium. Recycling aluminum requires no electrolysis, thus it is not treated in this way.

The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer. Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al2O3), the rest being a mixture of silica, various iron oxides, and titanium dioxide. The aluminium oxide must be further purified before it can be refined into aluminium.

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.

<span class="mw-page-title-main">Sodium aluminate</span> Chemical compound

Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate (anhydrous) is a white crystalline solid having a formula variously given as NaAlO2, NaAl(OH)4 (hydrated), Na2O·Al2O3, or Na2Al2O4. Commercial sodium aluminate is available as a solution or a solid.
Other related compounds, sometimes called sodium aluminate, prepared by reaction of Na2O and Al2O3 are Na5AlO4 which contains discrete AlO45− anions, Na7Al3O8 and Na17Al5O16 which contain complex polymeric anions, and NaAl11O17, once mistakenly believed to be β-alumina, a phase of aluminium oxide.

<span class="mw-page-title-main">Plasma electrolytic oxidation</span>

Plasma electrolytic oxidation (PEO), also known as electrolytic plasma oxidation (EPO) or microarc oxidation (MAO), is an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the oxide layer. This process can be used to grow thick, largely crystalline, oxide coatings on metals such as aluminium, magnesium and titanium. Because they can present high hardness and a continuous barrier, these coatings can offer protection against wear, corrosion or heat as well as electrical insulation.

<span class="mw-page-title-main">Aluminium silicate</span> Chemical compound

Aluminum silicate (or aluminium silicate) is a name commonly applied to chemical compounds which are derived from aluminium oxide, Al2O3 and silicon dioxide, SiO2 which may be anhydrous or hydrated, naturally occurring as minerals or synthetic. Their chemical formulae are often expressed as xAl2O3·ySiO2·zH2O. It is known as E number E559.

<span class="mw-page-title-main">Indium(III) oxide</span> Chemical compound

Indium(III) oxide (In2O3) is a chemical compound, an amphoteric oxide of indium.

<span class="mw-page-title-main">Sodium hexafluoroaluminate</span> Chemical compound

Sodium hexafluoroaluminate is an inorganic compound with formula Na3AlF6. This white solid, discovered in 1799 by Peder Christian Abildgaard (1740–1801), occurs naturally as the mineral cryolite and is used extensively in the industrial production of aluminium. The compound is the sodium (Na+) salt of the hexafluoroaluminate (AlF63−) ion.

Aluminium carbide, chemical formula Al4C3, is a carbide of aluminium. It has the appearance of pale yellow to brown crystals. It is stable up to 1400 °C. It decomposes in water with the production of methane.

<span class="mw-page-title-main">Thermal barrier coating</span> Form of exhaust heat management

Thermal barrier coatings (TBCs) are advanced materials systems usually applied to metallic surfaces on parts operating at elevated temperatures, such as gas turbine combustors and turbines, and in automotive exhaust heat management. These 100 μm to 2 mm thick coatings of thermally insulating materials serve to insulate components from large and prolonged heat loads and can sustain an appreciable temperature difference between the load-bearing alloys and the coating surface. In doing so, these coatings can allow for higher operating temperatures while limiting the thermal exposure of structural components, extending part life by reducing oxidation and thermal fatigue. In conjunction with active film cooling, TBCs permit working fluid temperatures higher than the melting point of the metal airfoil in some turbine applications. Due to increasing demand for more efficient engines running at higher temperatures with better durability/lifetime and thinner coatings to reduce parasitic mass for rotating/moving components, there is significant motivation to develop new and advanced TBCs. The material requirements of TBCs are similar to those of heat shields, although in the latter application emissivity tends to be of greater importance.

Aluminium hydroxide oxide or aluminium oxyhydroxide, AlO(OH) is found as one of two well defined crystalline phases, which are also known as the minerals boehmite and diaspore. The minerals are important constituents of the aluminium ore, bauxite.

<span class="mw-page-title-main">Aluminium smelting</span> Process of extracting aluminium from its oxide alumina

Aluminium smelting is the process of extracting aluminium from its oxide, alumina, generally by the Hall-Héroult process. Alumina is extracted from the ore bauxite by means of the Bayer process at an alumina refinery.

<span class="mw-page-title-main">Aluminium oxide nanoparticle</span>

Nanosized aluminium oxide occurs in the form of spherical or nearly spherical nanoparticles, and in the form of oriented or undirected fibers.

Titanium adhesive bonding is an engineering process used in the aerospace industry, medical-device manufacture and elsewhere. Titanium alloy is often used in medical and military applications because of its strength, weight, and corrosion resistance characteristics. In implantable medical devices, titanium is used because of its biocompatibility and its passive, stable oxide layer. Also, titanium allergies are rare and in those cases mitigations like Parylene coating are used. In the aerospace industry titanium is often bonded to save cost, touch times, and the need for mechanical fasteners. In the past, Russian submarines' hulls were completely made of titanium because the non-magnetic nature of the material went undetected by the defense technology at that time. Bonding adhesive to titanium requires preparing the surface beforehand, and there is not a single solution for all applications. For example, etchant and chemical methods are not biocompatible and cannot be employed when the device will come into contact with blood and tissue. Mechanical surface roughness techniques like sanding and laser roughening may make the surface brittle and create micro-hardness regions that would not be suitable for cyclic loading found in military applications. Air oxidation at high temperatures will produce a crystalline oxide layer at a lower investment cost, but the increased temperatures can deform precision parts. The type of adhesive, thermosetting or thermoplastic, and curing methods are also factors in titanium bonding because of the adhesive's interaction with the treated oxide layer. Surface treatments can also be combined. For example, a grit blast process can be followed by a chemical etch and a primer application.

<span class="mw-page-title-main">Aluminium compounds</span>

Aluminium (British and IUPAC spellings) or aluminum (North American spelling) combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and aluminium compounds tend towards covalency; this behaviour is similar to that of beryllium (Be2+), an example of a diagonal relationship. However, unlike all other post-transition metals, the underlying core under aluminium's valence shell is that of the preceding noble gas, whereas for gallium and indium it is that of the preceding noble gas plus a filled d-subshell, and for thallium and nihonium it is that of the preceding noble gas plus filled d- and f-subshells. Hence, aluminium does not suffer the effects of incomplete shielding of valence electrons by inner electrons from the nucleus that its heavier congeners do. Aluminium's electropositive behavior, high affinity for oxygen, and highly negative standard electrode potential are all more similar to those of scandium, yttrium, lanthanum, and actinium, which have ds2 configurations of three valence electrons outside a noble gas core: aluminium is the most electropositive metal in its group. Aluminium also bears minor similarities to the metalloid boron in the same group; AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class.

References

  1. ↑ Patnaik, P. (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN   978-0-07-049439-8.
  2. ↑ Raymond C. Rowe; Paul J. Sheskey; Marian E. Quinn (2009). "Adipic acid". Handbook of Pharmaceutical Excipients. Pharmaceutical Press. pp. 11–12. ISBN   978-0-85369-792-3.
  3. ↑ "Aluminum oxide_msds".
  4. 1 2 Material Properties Data: Alumina (Aluminum Oxide) Archived 2010-04-01 at the Wayback Machine . Makeitfrom.com. Retrieved on 2013-04-17.
  5. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN   978-0-618-94690-7.
  6. 1 2 NIOSH Pocket Guide to Chemical Hazards. "#0021". National Institute for Occupational Safety and Health (NIOSH).
  7. 1 2 3 4 5 "Alumina (Aluminium Oxide) – The Different Types of Commercially Available Grades". The A to Z of Materials. 3 May 2002. Archived from the original on 10 October 2007. Retrieved 27 October 2007.
  8. ↑ Elam, J. W. (October 2010). Atomic Layer Deposition Applications 6. The Electrochemical Society. ISBN   9781566778213.
  9. ↑ "Deltalumite".
  10. ↑ "List of Minerals". 21 March 2011.
  11. ↑ Gitzen, Walter (1970). Alumina as a Ceramic Material. Wiley.
  12. ↑ Dorre, Erhard; Hubner, Heinz (1984). Alumina, Processing, Properties, and Applications. Berlin; New York: Springer-Verlag. p. 344.
  13. ↑ Ruys, Andrew J. (2019). Alumina Ceramics: Biomedical and Industrial Applications. Duxford, UK: Elsevier. p. 558. ISBN   978-0-08-102442-3.
  14. ↑ Campbell, Timothy; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya; Ogata, Shuji; Rodgers, Stephen (1999). "Dynamics of Oxidation of Aluminium Nanoclusters using Variable Charge Molecular-Dynamics Simulations on Parallel Computers" (PDF). Physical Review Letters. 82 (24): 4866. Bibcode:1999PhRvL..82.4866C. doi:10.1103/PhysRevLett.82.4866. Archived (PDF) from the original on 2010-07-01.
  15. ↑ "EPCRA Section 313 Chemical List For Reporting Year 2006" (PDF). US EPA. Archived from the original (PDF) on 2008-05-22. Retrieved 2008-09-30.
  16. 1 2 I. Levin; D. Brandon (1999). "Metastable Alumina Polymorphs: Crystal Structures and Transition Sequences". Journal of the American Ceramic Society. 81 (8): 1995–2012. doi:10.1111/j.1151-2916.1998.tb02581.x.
  17. 1 2 3 Paglia, G. (2004). "Determination of the Structure of γ-Alumina using Empirical and First Principles Calculations Combined with Supporting Experiments" (free download). Curtin University of Technology, Perth. Retrieved 2009-05-05.
  18. ↑ Wiberg, E.; Holleman, A. F. (2001). Inorganic Chemistry. Elsevier. ISBN   978-0-12-352651-9.
  19. 1 2 Skinner, L.B.; et al. (2013). "Joint diffraction and modeling approach to the structure of liquid alumina". Phys. Rev. B. 87 (2): 024201. Bibcode:2013PhRvB..87b4201S. doi: 10.1103/PhysRevB.87.024201 .
  20. ↑ Paradis, P.-F.; et al. (2004). "Non-Contact Thermophysical Property Measurements of Liquid and Undercooled Alumina". Jpn. J. Appl. Phys. 43 (4): 1496–1500. Bibcode:2004JaJAP..43.1496P. doi:10.1143/JJAP.43.1496. S2CID   250779901.
  21. ↑ Shi, C; Alderman, O L G; Berman, D; Du, J; Neuefeind, J; Tamalonis, A; Weber, R; You, J; Benmore, C J (2019). "The structure of amorphous and deeply supercooled liquid alumina". Frontiers in Materials. 6 (38): 38. Bibcode:2019FrMat...6...38S. doi: 10.3389/fmats.2019.00038 .
  22. ↑ "Bauxite and Alumina Statistics and Information". USGS. Archived from the original on 6 May 2009. Retrieved 2009-05-05.
  23. ↑ "Aloxite". ChemIndustry.com database. Archived from the original on 25 June 2007. Retrieved 24 February 2007.
  24. ↑ Evans, K. A. (1993). "Properties and uses of aluminium oxides and aluminium hydroxides". In Downs, A. J. (ed.). The Chemistry of Aluminium, Indium and Gallium. Blackie Academic. ISBN   978-0751401035.
  25. ↑ "Alumina". INCI Decoder. Archived from the original on 5 February 2023. Retrieved 20 June 2023.
  26. ↑ "Alumina (Ingredient Explained + Products)". SkinSort. Archived from the original on 15 October 2023. Retrieved 15 October 2023.
  27. ↑ Akers, Michael J. (2016-04-19). Sterile Drug Products: Formulation, Packaging, Manufacturing and Quality. CRC Press. ISBN   9781420020564.
  28. ↑ Hudson, L. Keith; Misra, Chanakya; Perrotta, Anthony J.; Wefers, Karl and Williams, F. S. (2002) "Aluminum Oxide" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a01_557.
  29. ↑ Mallick, P.K. (2008). Fiber-reinforced composites materials, manufacturing, and design (3rd ed., [expanded and rev. ed.] ed.). Boca Raton, FL: CRC Press. pp. Ch.2.1.7. ISBN   978-0-8493-4205-9.
  30. ↑ "Ballistic Resistance of Body Armor" (PDF). US Department of Justice. NIJ. Retrieved 31 August 2018.
  31. ↑ Osborn, Joseph H. (2014). "understanding and specifying anodizing: what a manufacturer needs to know". OMW Corporation. Archived from the original on 2016-11-20. Retrieved 2018-06-02.
  32. ↑ Higashi GS, Fleming (1989). "Sequential surface chemical reaction limited growth of high quality Al2O3 dielectrics". Appl. Phys. Lett. 55 (19): 1963–65. Bibcode:1989ApPhL..55.1963H. doi:10.1063/1.102337.
  33. ↑ Kim JB; Kwon DR; Chakrabarti K; Lee Chongmu; Oh KY; Lee JH (2002). "Improvement in Al2O3 dielectric behavior by using ozone as an oxidant for the atomic layer deposition technique". J. Appl. Phys. 92 (11): 6739–42. Bibcode:2002JAP....92.6739K. doi:10.1063/1.1515951.
  34. ↑ Kim, Jaebum; Chakrabarti, Kuntal; Lee, Jinho; Oh, Ki-Young; Lee, Chongmu (2003). "Effects of ozone as an oxygen source on the properties of the Al2O3 thin films prepared by atomic layer deposition". Mater Chem Phys. 78 (3): 733–38. doi:10.1016/S0254-0584(02)00375-9.
  35. ↑ Belkin, A.; Bezryadin, A.; Hendren, L.; Hubler, A. (20 April 2017). "Recovery of Alumina Nanocapacitors after High Voltage Breakdown". Scientific Reports. 7 (1): 932. Bibcode:2017NatSR...7..932B. doi:10.1038/s41598-017-01007-9. PMC   5430567 . PMID   28428625.
  36. ↑ "GE Innovation Timeline 1957–1970". Archived from the original on 16 February 2009. Retrieved 2009-01-12.
  37. ↑ "DailyMed - JUNEL FE 1/20- norethindrone acetate and ethinyl estradiol, and ferrous fumarate". dailymed.nlm.nih.gov. Archived from the original on 2017-03-13. Retrieved 2017-03-13.
  38. ↑ V.B. Mikhailik, H. Kraus (2005). "Low-temperature spectroscopic and scintillation characterisation of Ti-doped Al2O3". Nucl. Instr. Phys. Res. A. 546 (3): 523–534. Bibcode:2005NIMPA.546..523M. doi:10.1016/j.nima.2005.02.033.
  39. ↑ Farndon, John (2001). Aluminium . Marshall Cavendish. p.  19. ISBN   9780761409472. Aluminium oxide is also used to make spark plug insulators.
  40. ↑ de Carle, Donald (1969). Practical Watch Repair. N.A.G. Press Ltd. p. 164. ISBN   0719800307.
  41. ↑ "Kashima Coat - Products / Services | Next-generation anodize boasting light weight, high lubrication, and superb wear resistance. The answer is Miyaki's Kashima Coat".


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