Gadolinium(III) oxide: Difference between revisions

| verifiedrevid = 396139502

| ImageFile =Gd2O3powder.jpg

| OtherNames = gadolinium sesquioxide, gadolinium trioxide

| Density = 7.407 g/cm³ (15 °C) <br> 7.07 g/cm³ (25 °C) <ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, ISBN 0070494398</ref>

| SolubilityProduct = 1.8×10^–23

| MeltingPt = 2420 °C

| BoilingPt =

| CrystalStruct = [[Monoclinic]], [[cubic]]

}}

| ExternalMSDS = [http://www.espimetals.com/msds's/gadoliniumoxide.pdf External MSDS]

| EUClass = not listed

'''Gadolinium(III) oxide''' (archaically '''gadolinia''') is a [[inorganic compound]] with the [[chemical formula|formula]] [[Gadolinium|Gd₂]][[Oxide|O₃]]. It is one of the most commonly available forms of the [[rare earth element]] gadolinium, derivatives of which are potential contrast agents for [[magnetic resonance imaging]].

==Structure==

[[File:Gd2O3structure.jpg|thumb|left|upright|Monoclinic Gd₂O₃]]

Gadolinium oxide has two most common structures: [[monoclinic]] ([[Pearson symbol]] mS30, [[space group]] C2/m, No. 12) and cubic ([[Pearson symbol|cI80]], Ia{{overline|3}}, No. 206). The cubic structure is similar to that of [[manganese(III) oxide]], which, as a mineral, is also called [[bixbyite]] (then with a minor iron(III) content). There are two types of gadolinium sites in the cubic structure, both with a coordination number of 6 but with different geometry of the surrounding oxygen atoms.<ref>Wells A.F. (1984) ''Structural Inorganic Chemistry'' 5th edition Oxford Science Publications ISBN 0-19-855370-6</ref> At room temperature, the cubic structure is the most stable and a phase change to the monoclinic structure takes place at 1200 °C. From 2100 °C and up to the melting point at 2420 °C, a hexagonal phase dominates.

==Preparation and chemistry==

Gadolinium oxide can be formed by thermal decomposition of the hydroxide, nitrate, carbonate, or oxalates.<ref>Cotton, S. (2006) [http://books.google.com/books?id=SvAbtU6XvzgC&pg=PA6 Lanthanide and Actinide Chemistry] Wiley ISBN 0-470-01006-1 p.6</ref> Gadolinium oxide forms on the surface of gadolinium metal.

Gadolinium oxide is a rather basic oxide, indicated by its ready reaction with carbon dioxide to give carbonates. It dissolves readily in the common mineral acids with the complication that the [[oxalate]], fluoride, sulfate and phosphate are very insoluble in water and may coat the grains of oxide, there by preventing the complete dissolution.<ref>Yost, D. M, Russell, H. Jr., Garner, C. S. The Rare-Earth Elements and their Compounds, Wiley, 1947.</ref>

==Nanoparticles of Gd₂O₃==

Several methods are known for the synthesis of gadolinium oxide nanoparticles, mostly based on precipitation of the hydroxide by the reaction of gadolinium ions with hydroxide, followed by thermal dehydration to the oxide. The nanoparticles are always coated with a protective material to avoid the formation of larger polycrystalline aggregates.<ref name=r4>{{cite journal|doi=10.1016/j.acra.2005.11.005|title=Investigations into the Physicochemical Properties of Dextran Small Particulate Gadolinium Oxide Nanoparticles|year=2006|last1=McDonald|first1=M|last2=Watkin|first2=K|journal=Academic Radiology|volume=13|pages=421|pmid=16554221|issue=4}}</ref><ref name=r5>{{cite journal|doi=10.1021/ja068356j|title=Hybrid Gadolinium Oxide Nanoparticles:  Multimodal Contrast Agents for in Vivo Imaging|year=2007|last1=Bridot|first1=Jean-Luc|last2=Faure|first2=Anne-Charlotte|last3=Laurent|first3=Sophie|last4=Rivière|first4=Charlotte|last5=Billotey|first5=Claire|last6=Hiba|first6=Bassem|last7=Janier|first7=Marc|last8=Josserand|first8=VéRonique|last9=Coll|first9=Jean-Luc|journal=Journal of the American Chemical Society|volume=129|pages=5076|pmid=17397154|issue=16}}</ref><ref name=r6>{{cite journal|doi=10.1007/s10334-006-0039-x|title=High proton relaxivity for gadolinium oxide nanoparticles|pmid=16909260|year=2006|last1=Engström|first1=Maria|last2=Klasson|first2=Anna|last3=Pedersen|first3=Henrik|last4=Vahlberg|first4=Cecilia|last5=Käll|first5=Per-Olov|last6=Uvdal|first6=Kajsa|journal=Magnetic Resonance Materials in Physics, Biology and Medicine|volume=19|issue=4|pages=180}}</ref>

Nanoparticles of gadolinium oxide is a potential contrast agent for [[magnetic resonance imaging]] (MRI). A [[dextran]]-coated preparation of 20–40&nbsp;nm sized gadolinium oxide particles had a relaxivity of 4.8 s^–1mM^–1 per gadolinium ion at 7.05 T (an unusually high field compared to the clinically used MRI scanners which mostly range from 0.5 to 3 T).<ref name=r4/> Smaller particles, between 2 and 7&nbsp;nm, were tested as a MRI agent in.<ref name=r5/><ref name=r6/>

==References==

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