“Promethium(III) oxide”的意思、由来-开放百科全书

词条

Promethium(III) oxide

释义

Crystal structure
References

{{chembox
| 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.jpg
| ImageCaption2 = Hexagonal form
| IUPACName = Promethium(III) oxide
| OtherNames = Promethium sesquioxide
| Section1 = {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo = 12036-25-8
| RTECS =
| Section2 = {{Chembox Properties
| Formula = Pm₂O₃
| MolarMass = 337.824 g/mol
| Appearance =
| Density =
| Solubility =
| MeltingPt =~2320 °C^[1]
| BoilingPt =
| BandGap =
}}
| Section3 = {{Chembox Structure
| CrystalStruct = Cubic
| SpaceGroup =
| Section4 = {{Chembox Related
| OtherAnions = Promethium(III) chloride
| OtherCations = Neodymium(III) oxide, Samarium(III) oxide, Neptunium(III) oxide}}
}}

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:^[1]

Form	Pearson symbol	Space group	No.	a,b,c (nm)	β(deg)	Z	Density (g/cm³)
Cubic	cI80	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	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

1. ^¹{{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}}

3 : Oxides|Promethium compounds|Sesquioxides

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