Aluminium diboride

{{chembox

| verifiedrevid = 418541969

| ImageFile = Magnesium-diboride-3D-balls.png

| ImageSize =

| IUPACName = aluminium diboride

| OtherNames = aluminium boride

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 21171253

| PubChem = 24884166

| InChI = 1/Al.B2/c;1-2/q-2;+2/rAlB2/c1-2-3-1

| InChIKey = XGNZNBRDPPLKTC-DOGMWQOPAK

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/Al.B2/c;1-2/q-2;+2

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = XGNZNBRDPPLKTC-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 12041-50-8

| EINECS = 234-923-7

| SMILES = B1=B[Al]1

}}

|Section2={{Chembox Properties

| Formula = AlB₂

| MolarMass = 48.604 g/mol{{RubberBible92nd|page=4.45}}

| Appearance = Copper-red solid

| Density = 3.19 g/cm³

| MeltingPt = >920 °C

| MeltingPt_notes = (decomposes)

| BoilingPt =

| Solubility = insoluble

}}

|Section3={{Chembox Structure

| Structure_ref ={{cite journal|doi=10.1021/ja01604a003|title=The Preparation of Aluminium Diboride, AlB21|journal=Journal of the American Chemical Society|volume=78|issue=23|pages=5977–5978|year=1956|last1=Felten|first1=Edward J}}

| CrystalStruct = Hexagonal, hP3

| SpaceGroup = P6/mmm, No. 191

| LattConst_a = 0.3009 nm

| LattConst_b = 0.3009 nm

| LattConst_c = 0.3262 nm,

| LattConst_alpha = 90

| LattConst_beta = 90

| LattConst_gamma = 120

| UnitCellFormulas =1

}}

|Section4={{Chembox Thermochemistry

| DeltaHf = −151 kJ/mol

| Entropy = 34.7 J/mol K

| HeatCapacity = 43.6 J/mol K

}}

|Section7={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

}}

}}

Aluminium diboride (AlB₂) is a chemical compound made from the metal aluminium and the metalloid boron. It is one of two compounds of aluminium and boron, the other being AlB₁₂, which are both commonly referred to as aluminium boride.

Structurally the B atoms form graphite-like sheets with Al atoms between them, and this is very similar to the structure of magnesium diboride. Single crystals of AlB₂ exhibit metallic conductivity along the axis parallel to the basal hexagonal plane.{{cite journal|title=On the electronic and structural properties of aluminium diboride Al_0.9B₂|journal=Journal of Solid State Chemistry |volume=177 |issue=2 |pages=389 |doi=10.1016/j.jssc.2002.12.001 |year=2004 |last1=Burkhardt |first1=U |last2=Gurin |first2=Vladimir |last3=Haarmann |first3=Frank |last4=Borrmann |first4=Horst |last5=Schnelle |first5=Walter |last6=Yaresko |first6=Alexander |last7=Grin |first7=Yuri |bibcode=2004JSSCh.177..389B }}

Aluminium boride is considered a hazardous substance as it reacts with acids and hydrogen gas to produce toxic gases. For example, it reacts with hydrochloric acid to release borane and aluminium chloride.

The crystal structure of AlB₂ is often used as a prototype structure to describe intermetallic compounds. There are a large number of structure types that fall within the AlB₂ structural family.{{cite journal | last1=Hoffmann | first1=R.-D. | last2=Pöttgen | first2=Rainer | title=AlB₂-related intermetallic compounds – a comprehensive view based on group-subgroup relations | journal=Zeitschrift für Kristallographie - Crystalline Materials | publisher=Walter de Gruyter GmbH | volume=216 | issue=3 | date=2001-01-01 | pages=127–145 | issn=2196-7105 | doi=10.1524/zkri.216.3.127.20327 | bibcode=2001ZK....216..127H | s2cid=98251655 }}