:Promethium(III) oxide

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| Watchedfields = changed

| verifiedrevid = 450432046

| ImageFile = Pm oxide.jpg

| ImageCaption = Powdered promethium oxide in a metal tray

| ImageFile1 = Kristallstruktur Indiumoxid.png

| ImageCaption1 = Cubic form

| ImageFile2 = La2O3structure.svg

| ImageCaption2 = Hexagonal form

| IUPACName = Promethium(III) oxide

| OtherNames = Promethium sesquioxide

| Section1 = {{Chembox Identifiers

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

| CASNo = 12036-25-8

| PubChem = 11602575

| RTECS =

| SMILES = [O-2].[O-2].[O-2].[Pm+3].[Pm+3]

| StdInChI=1S/3O.2Pm/q3*-2;2*+3

| StdInChIKey = UPEMFLOMQVFMCZ-UHFFFAOYSA-N

}}

| Section2 = {{Chembox Properties

| Formula = Pm₂O₃

| MolarMass = 337.824 g/mol

| Appearance =

| Density =

| Solubility =

| MeltingPt =~2320 °C

| BoilingPt =

| BandGap =

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| Section3 = {{Chembox Structure

| CrystalStruct = Cubic

| SpaceGroup =

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| Section4 = {{Chembox Related

| OtherAnions = Promethium(III) chloride

| OtherCations = Neodymium(III) oxide, Samarium(III) oxide, Neptunium(III) oxide}}

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Promethium(III) oxide is a compound with the formula Pm₂O₃. It is the most common form of promethium.

Crystal structure

Promethium oxide exists in three major crystalline forms:{{cite journal|doi=10.1111/j.1151-2916.1972.tb11329.x|title=Polymorphic Modifications of Pm₂O₃|year=1972|last1=Chikalla|first1=T. D.|last2=McNeilly|first2=C. E.|last3=Roberts|first3=F. P.|journal=Journal of the American Ceramic Society|volume=55|issue=8|pages=428}}

class=wikitable !Form !Pearson symbol !Space group !No. !a,b,c (nm) !β(deg) !Z !Density (g/cm³)
Cubic	cI80	Ia{{overline\|3}}	206	1.099		16	6.85
Monoclinic	mS30	C2/m	12	1.422; 0.365; 0.891	100.1	6	7.48
Hexagonal	hP5	P{{overline\|3}}m1	164	0.3802; 0.3802; 0.5954		1	7.62

*a, b and c are lattice parameters, Z is the number of formula units per unit cell, density is calculated from X-ray data.

The low-temperature cubic form converts to the monoclinic structure upon heating to 750–800 °C, and this transition can only be reversed by melting the oxide. The transition from the monoclinic to hexagonal form occurs at 1740 °C.

References

Category:Promethium compounds

Category:Sesquioxides