Gadolinium(III) oxide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Gadolinium(III) oxide
Gadolinium(III) oxide
Identifiers
CAS number 12064-62-9 YesY
PubChem 159427
ChemSpider 140201 YesY
UNII 5480D0NHLJ YesY
RTECS number LW4790000
Jmol-3D images Image 1
Properties
Molecular formula Gd2O3
Molar mass 362.50 g/mol
Appearance white odorless powder
Density 7.407 g/cm3 (15 °C)
7.07 g/cm3 (25 °C) [1]
Melting point 2420 °C
Solubility in water insoluble
Solubility product, Ksp 1.8×10−23
Solubility soluble in acid
Structure
Crystal structure Monoclinic, cubic
Hazards
MSDS External MSDS
EU classification not listed
Related compounds
Other anions Gadolinium(III) chloride
Other cations Europium(III) oxide, Terbium(III) oxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Gadolinium(III) oxide (archaically gadolinia) is an inorganic compound with the formula Gd2O3. 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[edit]

Cubic Gd2O3

Gadolinium oxide adopts two structures. The cubic (cI80, Ia3), No. 206) structure is similar to that of manganese(III) oxide. The cubic structure features two types of gadolinium sites, each with a coordination number of 6 but with different coordination geometries. The second polymorph is monoclinic (Pearson symbol mS30, space group C2/m, No. 12).[2] At room temperature, the cubic structure is more stable. The phase change to the monoclinic structure takes place at 1200 °C. Above 2100 °C to the melting point at 2420 °C, a hexagonal phase dominates.

Preparation and chemistry[edit]

Gadolinium oxide can be formed by thermal decomposition of the hydroxide, nitrate, carbonate, or oxalates.[3] 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, thereby preventing the complete dissolution.[4]

Nanoparticles of Gd2O3[edit]

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.[5][6][7]

Nanoparticles of gadolinium oxide is a potential contrast agent for magnetic resonance imaging (MRI). A dextran-coated preparation of 20–40 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).[5] Smaller particles, between 2 and 7 nm, were tested as a MRI agent in.[6][7]

References[edit]

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications. ISBN 0-19-855370-6.
  3. ^ Cotton, S. (2006) Lanthanide and Actinide Chemistry Wiley ISBN 0-470-01006-1 p.6
  4. ^ Yost, D. M, Russell, H. Jr., Garner, C. S. The Rare-Earth Elements and their Compounds, Wiley, 1947.
  5. ^ a b McDonald, M; Watkin, K (2006). "Investigations into the Physicochemical Properties of Dextran Small Particulate Gadolinium Oxide Nanoparticles". Academic Radiology 13 (4): 421–7. doi:10.1016/j.acra.2005.11.005. PMID 16554221. 
  6. ^ a b Bridot, Jean-Luc; Faure, Anne-Charlotte; Laurent, Sophie; Rivière, Charlotte; Billotey, Claire; Hiba, Bassem; Janier, Marc; Josserand, VéRonique et al. (2007). "Hybrid Gadolinium Oxide Nanoparticles: Multimodal Contrast Agents for in Vivo Imaging". Journal of the American Chemical Society 129 (16): 5076–84. doi:10.1021/ja068356j. PMID 17397154. 
  7. ^ a b Engström, Maria; Klasson, Anna; Pedersen, Henrik; Vahlberg, Cecilia; Käll, Per-Olov; Uvdal, Kajsa (2006). "High proton relaxivity for gadolinium oxide nanoparticles". Magnetic Resonance Materials in Physics, Biology and Medicine 19 (4): 180–6. doi:10.1007/s10334-006-0039-x. PMID 16909260.