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{{for|the advanced persistent threat known as GADOLINIUM in cybersecurity|APT40}}
{{Use dmy dates|date=December 2020}}
{{Infobox gadolinium}}
'''Gadolinium''' is a [[chemical element]]; it has [[Symbol (chemistry)|symbol]] '''Gd''' and [[atomic number]] 64. It is a silvery-white metal when oxidation is removed. Gadolinium is a malleable and [[ductile]] [[rare-earth element]]. It reacts with atmospheric oxygen or moisture slowly to form a black [[oxide]] coating. Gadolinium below its [[Curie point]] of {{convert|20|C}} is [[ferromagnetism|ferromagnetic]], with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most [[paramagnetism|paramagnetic]] element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare earths because of their similar chemical properties.

Gadolinium was discovered in 1880 by [[Jean Charles Galissard de Marignac|Jean Charles de Marignac]], who detected its oxide by using spectroscopy. It is named after the mineral [[gadolinite]], one of the minerals in which gadolinium is found, itself named for the Finnish chemist [[Johan Gadolin]]. Pure gadolinium was first isolated by the chemist [[Félix Trombe]] in 1935.

Gadolinium possesses unusual [[metallurgy|metallurgical]] properties, to the extent that as little as 1% of gadolinium can significantly improve the workability and resistance to [[oxidation]] at high temperatures of iron, [[chromium]], and related metals. Gadolinium as a metal or a salt absorbs [[neutron]]s and is, therefore, used sometimes for shielding in [[neutron radiography]] and in [[nuclear reactor]]s.

Like most of the rare earths, gadolinium forms [[trivalent]] ions with fluorescent properties, and salts of gadolinium(III) are used as [[phosphor]]s in various applications.

Gadolinium(III) ions in water-soluble salts are highly toxic to mammals. However, [[chelation|chelated]] gadolinium(III) compounds prevent the gadolinium(III) from being exposed to the organism, and the majority is excreted by healthy<ref>{{cite journal | last1 = Donnelly | first1 = L. | last2 = Nelson | first2 = R. | year = 1998 | title = Renal excretion of gadolinium mimicking calculi on non-contrast CT | url = | journal = Pediatric Radiology | volume = 28 | issue = 6| page = 417 | doi = 10.1007/s002470050374 | pmid = 9634454 }}</ref> kidneys before it can deposit in tissues. Because of its [[paramagnetism|paramagnetic]] properties, solutions of chelated [[organic chemistry|organic]] gadolinium [[coordination complex|complexes]] are used as intravenously administered [[gadolinium-based MRI contrast agent]]s in medical [[magnetic resonance imaging]].

The main uses of gadolinium, in addition to use as a [[MRI contrast agent|contrast agent for MRI scans]], are in nuclear reactors, in alloys, as a phosphor in medical imaging, as a gamma ray emitter, in electronic devices, in optical devices, and in superconductors.

==Characteristics==
[[File:Gadolinium-2.jpg|thumb|left|150px|A sample of gadolinium metal]]

===Physical properties===
Gadolinium is the eighth member of the [[lanthanide]] series. In the [[periodic table]], it appears between the elements [[europium]] to its left and [[terbium]] to its right, and above the [[actinide]] [[curium]]. It is a silvery-white, [[malleability|malleable]], [[ductility|ductile]] [[rare-earth element]]. Its 64 electrons are arranged in the configuration of [Xe]4f<sup>7</sup>5d<sup>1</sup>6s<sup>2</sup>, of which the ten 4f, 5d, and 6s electrons are [[valence electron|valence]].

Like most other metals in the lanthanide series, three electrons are usually available as valence electrons. The remaining 4f electrons are too strongly bound: this is because the 4f orbitals penetrate the most through the inert xenon core of electrons to the nucleus, followed by 5d and 6s, and this increases with higher ionic charge. Gadolinium crystallizes in the [[hexagonal crystal system|hexagonal close-packed]] α-form at room temperature.   At temperatures above {{convert|1235|C}}, it forms or transforms into its β-form, which has a [[body-centered cubic]] structure.<ref name="Greenwood" />

The [[isotope]] gadolinium-157 has the highest [[thermal neutron|thermal-neutron]] [[neutron capture|capture]] cross-section among any stable nuclide: about 259,000 [[barn (unit)|barns]]. Only [[xenon-135]] has a higher capture cross-section, about 2.0&nbsp;million barns, but this isotope is [[radioactive]].<ref name="barn">{{cite journal |url= https://www.ncnr.nist.gov/resources/n-lengths/elements/gd.html |title= Gadolinium |access-date= 6 June 2009 |journal= Neutron News |volume= 3 |issue= 3 |date= 1992 |page= 29}}</ref>

Gadolinium is believed to be [[ferromagnetism|ferromagnetic]] at temperatures below {{convert|20|C}}<ref name="CRC2" /> and is strongly [[paramagnetism|paramagnetic]] above this temperature. In fact, at body temperature, gadolinium exhibits the greatest paramagnetic effect of any element.<ref name="Wininger">{{cite journal |last1=Wininger |first1=Kevin |title=Contrast Media's Molecular Architecture |journal=Radiologic Technology |date=January–February 2022 |volume=93 |issue=3 |page=341 |pmid=35017275 |url=https://cdn.mycrowdwisdom.com/asrt/CE%20Column/RADT22_JF_MolArch.pdf |access-date=27 November 2023}}</ref> There is evidence that gadolinium is a helical antiferromagnetic, rather than a ferromagnetic, below {{convert|20|C}}.<ref name="CoeySkumryev1999">{{cite journal |vauthors= Coey JM, Skumryev V, Gallagher K |journal=Nature |volume=401 |issue=6748 |year=1999 |pages=35–36|issn=0028-0836|doi=10.1038/43363 |title= Rare-earth metals: Is gadolinium really ferromagnetic?|bibcode=1999Natur.401...35C|s2cid=4383791 }}</ref> Gadolinium demonstrates a [[magnetic refrigeration#The magnetocaloric effect|magnetocaloric effect]] whereby its temperature increases when it enters a magnetic field and decreases when it leaves the magnetic field. A significant magnetocaloric effect is observed at higher temperatures, up to about 300&nbsp;[[kelvin]]s, in the compounds Gd<sub>5</sub>(Si<sub>1−''x''</sub>Ge<sub>''x''</sub>)<sub>4</sub>.<ref name="r27" />

Individual gadolinium atoms can be isolated by encapsulating them into [[fullerene]] molecules, where they can be visualized with a [[transmission electron microscope]].<ref>{{cite journal |doi= 10.1021/nl034621c |title= Evidence for the Intramolecular Motion of Gd Atoms in a Gd<sub>2</sub>@C<sub>92</sub> Nanopeapod |date= 2003 |author= Suenaga, Kazu |journal= Nano Letters |volume= 3 |page= 1395 |first2= Risa |first3= Takashi |first4= Toshiya |first5= Hisanori |first6= Sumio |last2= Taniguchi |last3= Shimada |last4= Okazaki |last5= Shinohara |last6= Iijima|bibcode= 2003NanoL...3.1395S |issue= 10}}</ref> Individual Gd atoms and small Gd clusters can be incorporated into [[carbon nanotubes]].<ref>{{cite journal |vauthors= Hashimoto A, Yorimitsu H, Ajima K, Suenaga K, Isobe H, Miyawaki J, Yudasaka M, Iijima S, Nakamura E |title= Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn |journal= Proceedings of the National Academy of Sciences, USA |volume= 101 |issue= 23 |pages= 8527–30 |date= June 2004 |pmid= 15163794 |pmc= 423227 |doi= 10.1073/pnas.0400596101 |bibcode= 2004PNAS..101.8527H|doi-access= free }}</ref>

===Chemical properties===
{{Category see also|Gadolinium compounds}}
Gadolinium combines with most elements to form Gd(III) derivatives. It also combines with nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon, and [[arsenic]] at elevated temperatures, forming binary compounds.<ref name="Wiberg">{{Holleman&Wiberg}}</ref>

Unlike the other rare-earth elements, metallic gadolinium is relatively stable in dry air. However, it [[tarnish]]es quickly in moist air, forming a loosely-adhering [[gadolinium(III) oxide]] ({{chem2|Gd2O3}}):
:{{chem2|4 Gd + 3 O2 → 2 Gd2O3}},
which [[spall#Corrosion|spalls]] off, exposing more surface to oxidation.

Gadolinium is a strong [[reducing agent]], which reduces oxides of several metals into their elements. Gadolinium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form [[gadolinium(III) hydroxide]] ({{chem2|Gd(OH)3}}):
:{{chem2|2 Gd + 6 H2O → 2 Gd(OH)3 + 3 H2}}.

Gadolinium metal is attacked readily by dilute [[sulfuric acid]] to form solutions containing the colorless Gd(III) ions, which exist as {{chem2|[Gd(H2O)9](3+)}} complexes:<ref>{{cite web |url= https://www.webelements.com/gadolinium/chemistry.html |title= Chemical reactions of Gadolinium |date= 1993–2018|author= Mark Winter|publisher= The University of Sheffield and WebElements |access-date=6 June 2009}}</ref>
:{{chem2|2 Gd + 3 H2SO4 + 18 H2O → 2 [Gd(H2O)9](3+) + 3 SO4(2-) + 3 H2}}.

====Chemical compounds====
In the great majority of its compounds, like many [[rare-earth metals]], gadolinium adopts the [[oxidation state]] +3. However, gadolinium can be found on rare occasions in the 0, +1 and +2 oxidation states. All four trihalides are known. All are white, except for the iodide, which is yellow. Most commonly encountered of the halides is [[gadolinium(III) chloride]] ({{chem2|GdCl3}}). The oxide dissolves in acids to give the salts, such as [[gadolinium(III) nitrate]].

Gadolinium(III), like most lanthanide ions, forms [[coordination complex|complexes]] with high [[coordination number]]s. This tendency is illustrated by the use of the chelating agent [[DOTA (chelator)|DOTA]], an octa[[denticity|dentate]] ligand. Salts of [Gd(DOTA)]<sup>−</sup> are useful in [[magnetic resonance imaging]]. A variety of related chelate complexes have been developed, including [[gadodiamide]].

Reduced gadolinium compounds are known, especially in the solid state. Gadolinium(II) halides are obtained by heating Gd(III) halides in presence of metallic Gd in [[tantalum]] containers. Gadolinium also forms the sesquichloride {{chem2|Gd2Cl3}}, which can be further reduced to GdCl by annealing at {{convert|800|C}}. This gadolinium(I) chloride forms platelets with layered graphite-like structure.<ref>{{cite book |page=1128 |url=https://books.google.com/books?id=U3MWRONWAmMC&pg=PA1128 |title= Advanced inorganic chemistry |edition= 6th |author= Cotton |publisher= Wiley-India |date= 2007 |isbn= 978-81-265-1338-3}}</ref>

===Isotopes===
{{Main|Isotopes of gadolinium}}

Naturally occurring gadolinium is composed of six stable isotopes, <sup>154</sup>Gd, <sup>155</sup>Gd, <sup>156</sup>Gd, <sup>157</sup>Gd, <sup>158</sup>Gd and <sup>160</sup>Gd, and one [[radioisotope]], <sup>152</sup>Gd, with the isotope <sup>158</sup>Gd being the most abundant (24.8% [[natural abundance]]).<ref>{{NUBASE2020}}</ref>

Thirty-three radioisotopes have been characterized, with the three most stable being alpha emitters: <sup>152</sup>Gd (naturally occurring) with a half-life of 1.08×10<sup>14</sup> years, <sup>150</sup>Gd with a half-life of 1.79×10<sup>6</sup> years, and <sup>148</sup>Gd (theoretically not [[beta-stable]]) with a half-life of 86.9 years. All of the remaining radioactive isotopes have half-lives less than a year, the majority of these having half-lives less than two minutes. There are also 10 metastable [[nuclear isomer|isomers]], with the most stable being <sup>143m</sup>Gd (t<sub>1/2</sub> = 110 seconds), <sup>145m</sup>Gd (t<sub>1/2</sub> = 85 seconds) and <sup>141m</sup>Gd (t<sub>1/2</sub> = 24.5 seconds).<ref>{{NUBASE2020}}</ref> The predicted double beta decay of <sup>160</sup>Gd has never been observed (an experimental lower limit on its [[half-life]] of more than 1.3×10<sup>21</sup> years has been measured<ref name="DBD">{{Cite journal |last1=Danevich |first1=F. A. |last2=Kobychev |first2=V. V. |last3=Ponkratenko |first3=O. A. |last4=Tretyak |first4=V. I. |last5=Zdesenko |first5=Yu. G. |date=2001-11-05 |title=Quest for double beta decay of 160Gd and Ce isotopes |url=https://www.sciencedirect.com/science/article/pii/S0375947401009836 |journal=Nuclear Physics A |volume=694 |issue=1 |pages=375–391 |doi=10.1016/S0375-9474(01)00983-6 |issn=0375-9474|arxiv=nucl-ex/0011020 }}</ref>).

The isotopes with [[atomic mass]]es lower than the most abundant stable isotope, <sup>158</sup>Gd, primarily decay by [[electron capture]] to isotopes of [[europium]]. At higher atomic masses, the primary [[decay mode]] is [[beta decay]] to isotopes of [[terbium]].{{cn|date=July 2025}}

==History==
Gadolinium is named after the mineral [[gadolinite]]. Gadolinite was first chemically analyzed by the Finnish chemist [[Johan Gadolin]] in 1794.<ref>{{cite journal |last1=Gadolin |first1=Johan |title=Undersokning af en svart tung Stenart ifrån Ytterby Stenbrott i Roslagen |journal=Kongliga Vetenskaps Academiens Nya Handlingar [Royal Academy of Science's New Proceedings] |date=1794 |volume=15 |pages=137–155 |url=https://www.biodiversitylibrary.org/item/180081#page/143/mode/1up |trans-title=Examination of a black heavy type of stone from Ytterby Quarry in Roslagen |language=Swedish}}</ref><ref>{{cite journal |last1=Gadolin |first1=J. |title=Von einer schwarazen, schweren Steinart aus Ytterby Steinbruch in Roslagen in Schweden |journal=Chemische Annalen für die Freunde der Naturlehre, Arzneygelahrtheit, Haushaltungskunst und Manufakturen [Chemical Annals for the Friends of Science, Medicine, Domestic Economy and Manufacture] |date=1796 |volume=1 |pages=313–329 |url=https://babel.hathitrust.org/cgi/pt?id=umn.31951000637445g&seq=319 |trans-title=Of a black, heavy type of stone from the Ytterby quarry in Roslagen in Sweden |language=German}}</ref> In 1802 German chemist Martin Klaproth gave gadolinite its name.<ref>{{cite book |last1=Klaproth |first1=Martin Heinrich |title=Beiträge zur chemischen Kenntniss der Mineralkörper |trans-title=Contribution to Our Knowledge of Mineral Substances |date=1802 |publisher=Heinrich August Rottmann |location=Berlin, (Germany) |pages=52–79 |url=https://books.google.com/books?id=bZU5AAAAcAAJ&pg=PA54 |language=German |chapter=Ch. LXXVI: Chemische Untersuchung des Gadolinits [Ch. 76: Chemical investigation of gadolinite }}  Because Gadolin had found a new ore (''"einer unbekannten Erdart"'' (an unknown type of ore)) in a mineral which had previously been called "Ytterbite" (because it had been found near the town of Ytterby in Sweden), Klaproth proposed to rename the mineral "Gadolinite".  From p. 54:  ''"Herr Gadolin hat also das Verdienst, diese neue Erde im gegenwärtigen Fossil zuerst entdeckt zu haben; weshalb ich auch, mit mehrern Naturforschern, dessen Namen Gadolinit der erstern Benennung Ytterbit vorziehe."''  (Mr. Gadolin thus has the merit of having first discovered this new ore in the present rock; for which reason I, with several [other] scientists, prefer the name "gadolinite" to the first name "ytterbite".) Klaproth used the name "gadolinite" as early as 1801:  {{cite journal |last1=Klaproth |title=Einige Bemerkungen über den Gadolinit, den Chryolith und die Honigsteinsäure |journal=Chemische Annalen für die Freunde der Naturlehre, Arzneygelahrtheit, Haushaltungskunst und Manufakturen [Chemical Annals for the Friends of Science, Medicine, Domestic Economy and Manufacture] |date=1801 |pages=307–308 |url=https://books.google.com/books?id=2qw5AAAAcAAJ&pg=PA307 |trans-title=Some observations on gadolinite, cryolite and mellitic acid |language=German}}</ref><ref name="Greenwood">{{Greenwood&Earnshaw2nd}}</ref> In 1880, the Swiss [[chemist]] [[Jean Charles Galissard de Marignac]] observed the spectroscopic lines from gadolinium in samples of [[gadolinite]] (which actually contains relatively little gadolinium, but enough to show a spectrum) and in the separate mineral [[cerite]]. The latter mineral proved to contain far more of the element with the new spectral line. De Marignac eventually separated a mineral oxide from cerite, which he realized was the oxide of this new element. He designated the element with the provisional symbol Yα. The French chemist [[Paul-Émile Lecoq de Boisbaudran]] named the element "gadolinium" in 1886.<ref name="Marshall">{{cite journal|last1=Marshall |first1=James L. |last2=Marshall |first2=Virginia R. |title=Rediscovery of the Elements: Yttrium and Johan Gadolin |journal=The Hexagon |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/gadolin.pdf |date=2008|issue=Spring|pages=8–11}}</ref><ref name="Virginia">{{cite journal |last1=Marshall |first1=James L. Marshall |last2=Marshall |first2=Virginia R. Marshall |title=Rediscovery of the elements: The Rare Earths–The Confusing Years |journal=The Hexagon |date=2015 |pages=72–77 |url=http://www.chem.unt.edu/~jimm/REDISCOVERY%207-09-2018/Hexagon%20Articles/rare%20earths%20II.pdf |access-date=30 December 2019}}</ref><ref name="Weeks">{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th }}</ref><ref name="XVI">{{cite journal | author = Weeks, Mary Elvira |author-link=Mary Elvira Weeks| title = The discovery of the elements: XVI. The rare earth elements | journal = Journal of Chemical Education | year = 1932 | volume = 9 | issue = 10 | pages = 1751–1773 | doi = 10.1021/ed009p1751 | bibcode=1932JChEd...9.1751W}}</ref> The pure element was isolated in 1935 by [[Félix Trombe]].<ref name="Trombe">{{Cite journal|author=Félix Trombe|url=http://gallica.bnf.fr/ark:/12148/bpt6k3152t/f459.image|title=L'isolement de gadolinium|journal=Comptes Rendus|year=1935|volume=200|pages=459–461}}</ref>

==Occurrence==
[[File:Gadolinitas.jpg|thumb|Gadolinite]]
Gadolinium is a constituent in many minerals, such as [[monazite]] and [[bastnäsite]]. The metal is too reactive to exist naturally. Paradoxically, as noted above, the mineral [[gadolinite]] actually contains only traces of this element. The abundance in the Earth's crust is about 6.2&nbsp;mg/kg.<ref name="Greenwood" /> The main mining areas are in China, the US, Brazil, Sri Lanka, India, and Australia with reserves expected to exceed one million tonnes. World production of pure gadolinium is about 400 tonnes per year. The only known mineral with essential gadolinium, [[lepersonnite-(Gd)]], is very rare.<ref>{{cite journal | last1 = Deliens | first1 = M. | last2 = Piret | first2 = P. | year = 1982 | title = Bijvoetite et lepersonnite, carbonates hydrates d'uranyle et des terres rares de Shinkolobwe, Zaïre | url = | journal = Canadian Mineralogist | volume = 20 | issue = | pages = 231–38 }}</ref><ref>{{cite web|url=https://www.mindat.org/min-2378.html |title=Lepersonnite-(Gd): Lepersonnite-(Gd) mineral information and data |website=Mindat.org |access-date=4 March 2016}}</ref>

==Production==
Gadolinium is produced both from monazite and [[bastnäsite]].
# Crushed minerals are extracted with [[hydrochloric acid]] or [[sulfuric acid]], which converts the insoluble oxides into soluble chlorides or sulfates.
# The acidic filtrates are partially neutralized with caustic soda to pH 3–4. [[Thorium]] precipitates as its hydroxide, and is then removed.
# The remaining solution is treated with [[ammonium oxalate]] to convert rare earths into their insoluble [[oxalate]]s. The oxalates are converted to oxides by heating.
# The oxides are dissolved in [[nitric acid]] that excludes one of the main components, [[cerium]], whose oxide is insoluble in HNO<sub>3</sub>.
# The solution is treated with [[magnesium nitrate]] to produce a crystallized mixture of double salts of gadolinium, [[samarium]] and [[europium]].
# The salts are separated by [[ion exchange]] chromatography.
# The rare-earth ions are then selectively washed out by a suitable complexing agent.<ref name="Greenwood" />

Gadolinium metal is obtained from its oxide or salts by heating it with [[calcium]] at {{convert|1450|C}} in an argon atmosphere. Sponge gadolinium can be produced by reducing molten GdCl<sub>3</sub> with an appropriate metal at temperatures below {{convert|1312|C}} (the melting point of Gd) at reduced pressure.<ref name="Greenwood" />

==Applications==<!--few real apps described below-->

Gadolinium has no large-scale applications, but it has a variety of specialized uses.

===Neutron absorber===
Because gadolinium has a high neutron cross-section, it is effective for use with [[neutron radiography]] and in shielding of [[nuclear reactors]]. It is used as a secondary, emergency shut-down measure in some nuclear reactors, particularly of the [[CANDU reactor]] type.<ref name="Greenwood" /> Gadolinium is used in [[nuclear marine propulsion]] systems as a [[burnable poison#Burnable poisons|burnable poison]]. The use of gadolinium in [[Neutron capture therapy of cancer|neutron capture therapy]] to target tumors has been investigated, and gadolinium-containing compounds have proven promising.<ref name="Kouri Polychronidou Loukas Megapanou 2023 pp. 127–149">{{cite journal | last1=Kouri | first1=Maria Anthi | last2=Polychronidou | first2=Konstantina | last3=Loukas | first3=Grigorios | last4=Megapanou | first4=Aikaterini | last5=Vagena | first5=Ioanna-Aglaia | last6=Gerardos | first6=Angelica M. | last7=Spyratou | first7=Ellas | last8=Eftsathopoulos | first8=Eftstathios P. | title=Consolidation of Gold and Gadolinium Nanoparticles: An Extra Step towards Improving Cancer Imaging and Therapy | journal=Journal of Nanotheranostics | publisher=MDPI AG | volume=4 | issue=2 | date=26 April 2023 | issn=2624-845X | doi=10.3390/jnt4020007 | pages=127–149| doi-access=free }}</ref>

===Alloys===
Gadolinium possesses unusual [[metallurgy|metallurgic]] properties, with as little as 1% of gadolinium improving the workability  of iron, [[chromium]], and related [[alloy]]s, and their resistance to high temperatures and [[oxidation]].<ref>{{Cite web|last=National Center for Biotechnology Information|title=Element Summary for AtomicNumber 64, Gadolinium|url=https://pubchem.ncbi.nlm.nih.gov/element/Gadolinium#section=Uses|access-date=25 October 2021|website=PubChem}}</ref>

===Magnetic contrast agent===
Gadolinium is [[paramagnetic]] at [[room temperature]], with a [[Curie temperature|ferromagnetic Curie point]] of {{convert|20|C}}.<ref name="CRC2">{{RubberBible86th|page=4.122}}</ref> Paramagnetic ions, such as gadolinium, increase [[nuclear spin]] relaxation rates, making gadolinium useful as a [[MRI contrast agent|contrast agent]] for [[magnetic resonance imaging]] (MRI). Solutions of [[organic chemistry|organic]] gadolinium [[coordination complex|complexes]] and gadolinium compounds are used as [[intravenous]] contrast agents to enhance images in medical  and [[magnetic resonance angiography]] (MRA) procedures. [[Magnevist]] is the most widespread example.<ref>{{cite book |pages=13;30|url= https://books.google.com/books?id=xpCffxNrCXYC&pg=PA13 |title= MRI in clinical practice |author=Liney, Gary |publisher=Springer |date= 2006 |isbn= 978-1-84628-161-7}}</ref><ref>{{cite journal |vauthors= Raymond KN, Pierre VC |title= Next generation, high relaxivity gadolinium MRI agents |journal= Bioconjugate Chemistry |volume= 16 |issue= 1 |pages= 3–8 |date= 2005 |pmid= 15656568 |doi= 10.1021/bc049817y }}</ref> Nanotubes packed with gadolinium, called "[[gadonanotube]]s", are 40 times more effective than the usual gadolinium contrast agent.<ref>Wendler, Ronda (1 December 2009) [https://web.archive.org/web/20110728091851/http://www.texasmedicalcenter.org/root/en/TMCServices/News/2009/12-01/Magnets+Guide+Stem+Cells+to+Damaged+Hearts.htm Magnets Guide Stem Cells to Damaged Hearts]. Texas Medical Center.</ref> Traditional gadolinium-based contrast agents are un-targeted, generally distributing throughout the body after injection, but will not readily cross the intact [[blood–brain barrier]].<ref name=pmid32418324>{{cite journal |vauthors=Bagnato F, Gauthier SA, Laule C, Moore G, Bove R, Cai Z, Cohen-Adad J, Harrison DM, Klawiter EC, Morrow SA, Öz G, Rooney WD, Smith SA, Calabresi PA, Henry RG, Oh J, Ontaneda D, Pelletier D, Reich DS, Shinohara RT, Sicotte NL |display-authors=6 |date=May 2020 |title=Imaging mechanisms of disease progression in multiple sclerosis: Beyond brain atrophy |journal=[[Journal of Neuroimaging]] |volume=30 |issue=3 |pages=251–266 |pmid=32418324 |doi=10.1111/jon.12700|s2cid=218677556 }}</ref> [[Brain tumors]], and other disorders that degrade the [[blood-brain]] barrier, allow these agents to penetrate into the brain and facilitate their detection by contrast-enhanced [[MRI]].  Similarly, [[delayed gadolinium-enhanced magnetic resonance imaging of cartilage]] uses an [[ionic compound]] agent, originally [[Magnevist]], that is excluded from healthy [[cartilage]] based on [[electrostatic repulsion]] but will enter [[proteoglycan]]-depleted cartilage in diseases such as [[osteoarthritis]].{{Medical citation needed|date=July 2024}}

===Phosphors===
Gadolinium is used as a phosphor in medical imaging. It is contained in the phosphor layer of [[X-ray]] detectors, suspended in a polymer matrix. [[Terbium]]-[[doping (semiconductors)|doped]] [[gadolinium oxysulfide]] (Gd<sub>2</sub>O<sub>2</sub>S:Tb) at the phosphor layer converts the X-rays released from the source into light. This material emits green light at 540&nbsp;nm because of the presence of Tb<sup>3+</sup>, which is very useful for enhancing the imaging quality. The energy conversion of Gd is up to 20%, which means that one fifth of the X-ray energy striking the phosphor layer can be converted into visible photons.{{citation needed|date=March 2023}} Gadolinium oxyorthosilicate (Gd<sub>2</sub>SiO<sub>5</sub>, GSO; usually doped by 0.1–1.0% of [[Cerium|Ce]]) is a single crystal that is used as a [[scintillator]] in medical imaging such as [[positron emission tomography]], and for detecting neutrons.<ref>{{cite journal|doi= 10.1117/1.1829713|title= Use of gadolinium oxyorthosilicate scintillators in x-ray radiometers|date= 2005 |vauthors= Ryzhikov VD, Grinev BV, Pirogov EN, Onyshchenko GM, Bondar VG, Katrunov KA, Kostyukevich SA |journal= Optical Engineering|volume= 44|page= 016403|bibcode= 2005OptEn..44a6403R}}</ref>

Gadolinium compounds were also used for making green [[phosphor]]s for color TV tubes.<ref>{{Cite journal |last1=Sajwan |first1=Reena K. |last2=Tiwari |first2=Samit |last3=Harshit |first3=Tulika |last4=Singh |first4=Ajaya Kumar |date=2017-10-10 |title=Recent progress in multicolor tuning of rare earth-doped gadolinium aluminate phosphors GdAlO3 |url=https://www.researchgate.net/publication/320308564 |journal=Optical and Quantum Electronics |language=en |volume=49 |issue=11 |page=344 |doi=10.1007/s11082-017-1158-5 |s2cid=254897308 |issn=1572-817X}}</ref>

===Gamma ray emitter===
Gadolinium-153 is produced in a nuclear reactor from elemental [[europium]] or enriched gadolinium targets. It has a half-life of {{val|240|10}} days and emits [[gamma radiation]] with strong peaks at 41&nbsp;keV and 102&nbsp;keV. It is used in many quality-assurance applications, such as line sources and calibration phantoms, to ensure that nuclear-medicine imaging systems operate correctly and produce useful images of radioisotope distribution inside the patient.<ref name="gd153">{{cite web |url=http://radioisotopes.pnl.gov/gadolinium.stm |title=Gadolinium-153 |publisher=Pacific Northwest National Laboratory |access-date=6 June 2009 |archive-url=https://web.archive.org/web/20090527014921/http://radioisotopes.pnl.gov/gadolinium.stm |archive-date=27 May 2009 }}</ref> It is also used as a gamma-ray source in X-ray absorption measurements and in [[bone density gauge]]s for [[osteoporosis]] screening.{{citation needed|date=March 2023}}

===Electronic and optical devices===
Gadolinium is used for making [[gadolinium yttrium garnet]] (Gd:Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>), which has [[microwave]] applications and is used in fabrication of various optical components and as substrate material for magneto-optical films.<ref>{{Cite journal |last1=Cuomo |first1=J. J. |last2=Chaudhari |first2=P. |last3=Gambino |first3=R. J. |date=1974-05-01 |title=Amorphous magnetic materials for bubble domain and magneto-optics application |journal=Journal of Electronic Materials |language=en |volume=3 |issue=2 |pages=517–529 |doi=10.1007/BF02652955 |bibcode=1974JEMat...3..517C |s2cid=97662638 |issn=1543-186X}}</ref>

===Electrolyte in fuel cells===
Gadolinium can also serve as an [[electrolyte]] in [[solid oxide fuel cell]]s (SOFCs). Using gadolinium as a [[dopant]] for materials like [[cerium(IV) oxide|cerium oxide]] (in the form of [[gadolinium-doped ceria]]) gives an electrolyte having both high [[Ionic conductivity (solid state)|ionic conductivity]] and low operating temperatures.

===Magnetic refrigeration via magnetocalorics===
Gadolinium is the standard reference material in the study of [[magnetic refrigeration]] near room temperature.<ref name="r27" />{{rp|1528}} Pure Gd itself exhibits a large magnetocaloric effect near its [[Curie temperature]] of {{convert|20|C}}, and this has sparked interest into producing Gd alloys having a larger effect and tunable Curie temperature. In Gd<sub>5</sub>(Si<sub>''x''</sub>Ge<sub>1−''x''</sub>)<sub>4</sub>, Si and Ge compositions can be varied to adjust the [[Curie temperature]].
Gadolinium-based materials, such as Gd<sub>5</sub>(Si<sub>''x''</sub>Ge<sub>1−''x''</sub>)<sub>4</sub>, are currently the most promising materials, owing to their high Curie temperature and giant magneto-caloric effect. 
Magnetic refrigeration could provide significant efficiency and environmental advantages over conventional refrigeration methods.<ref name="r27" />

===Superconductors===
Gadolinium barium copper oxide (GdBCO) is a superconductor<ref>{{Cite journal|last1=Shi|first1=Y|last2=Babu|first2=N Hari|last3=Iida|first3=K|last4=Cardwell|first4=D A|date=1 February 2008|title=Superconducting properties of Gd-Ba-Cu-O single grains processed from a new, Ba-rich precursor compound|journal=Journal of Physics: Conference Series|volume=97|issue=1|article-number=012250|doi=10.1088/1742-6596/97/1/012250|issn=1742-6596|bibcode=2008JPhCS..97a2250S|doi-access=free}}</ref><ref>{{Cite journal|last1=Cardwell|first1=D A|last2=Shi|first2=Y-H|last3=Hari Babu|first3=N|last4=Pathak|first4=S K|last5=Dennis|first5=A R|last6=Iida|first6=K|date=1 March 2010|title=Top seeded melt growth of Gd–Ba–Cu–O single grain superconductors|journal=Superconductor Science and Technology|volume=23|issue=3|article-number=034008|doi=10.1088/0953-2048/23/3/034008|issn=0953-2048|bibcode=2010SuScT..23c4008C|s2cid=121381965 }}</ref><ref>{{Cite journal|last1=Zhang|first1=Y F|last2=Wang|first2=J J|last3=Zhang|first3=X J|last4=Pan|first4=C Y|last5=Zhou|first5=W L|last6=Xu|first6=Y|last7=Liu|first7=Y S|last8=Izumi|first8=M|date=2017|title=Flux pinning properties of GdBCO bulk through the infiltration and growth process|journal=IOP Conference Series: Materials Science and Engineering|volume=213|issue=1|article-number=012049|doi=10.1088/1757-899X/213/1/012049|issn=1757-8981|bibcode=2017MS&E..213a2049Z|doi-access=free}}</ref> with applications in superconducting motors or generators such as in wind turbines.<ref>{{Cite web|url=https://www.nextbigfuture.com/2018/11/european-ecoswing-builds-first-full-scale-superconductor-wind-turbine.html|title=European EcoSwing Builds First Full Scale Superconductor Wind Turbine|last=Wang|first=Brian|date=22 November 2018}}</ref> It can be manufactured in the same way as the most widely researched cuprate high temperature superconductor, [[yttrium barium copper oxide]] (YBCO) and uses an analogous chemical composition (GdBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−''δ''</sub> ).<ref>{{Cite journal|last1=Zhang|first1=Yufeng|last2=Zhou|first2=Difan|last3=Ida|first3=Tetsuya|last4=Miki|first4=Motohiro|last5=Izumi|first5=Mitsuru|date=1 April 2016|title=Melt-growth bulk superconductors and application to an axial-gap-type rotating machine|journal=Superconductor Science and Technology|volume=29|issue=4|article-number=044005|doi=10.1088/0953-2048/29/4/044005|issn=0953-2048|bibcode=2016SuScT..29d4005Z|s2cid=124770013 }}</ref> It was used in 2014 to set a new world record for the highest trapped magnetic field in a bulk [[High-temperature superconductivity|high temperature superconductor]], with a field of 17.6T being trapped within two GdBCO bulks.<ref>{{Cite journal|last1=Durrell|first1=J H|last2=Dennis|first2=A R|last3=Jaroszynski|first3=J|last4=Ainslie|first4=M D|last5=Palmer|first5=K G B|last6=Shi|first6=Y-H|last7=Campbell|first7=A M|last8=Hull|first8=J|last9=Strasik|first9=M|date=1 August 2014|title=A trapped field of 17.6 T in melt-processed, bulk Gd-Ba-Cu-O reinforced with shrink-fit steel|journal=Superconductor Science and Technology|volume=27|issue=8|article-number=082001|doi=10.1088/0953-2048/27/8/082001|issn=0953-2048|bibcode=2014SuScT..27h2001D|arxiv=1406.0686|s2cid=4890081}}</ref><ref>{{Cite web|url=https://www.guinnessworldrecords.com/world-records/439929-strongest-magnetic-field-trapped-in-a-superconductor/|title=Strongest magnetic field trapped in a superconductor|date=25 June 2014 |access-date=15 August 2019}}</ref>

===Asthma treatment===
Gadolinium is being investigated as a possible treatment for preventing lung tissue scarring in [[asthma]]. A positive effect has been observed in mice.<ref>[https://www.bbc.co.uk/news/health-68731197 Asthma: Scientists find new cause of lung damage – BBC News]</ref>

===Niche and former applications===
Gadolinium is used for [[neutrino#antineutrinos|antineutrino]] detection in the Japanese [[Super-Kamiokande]] detector in order to sense [[supernova]] explosions. Low-energy neutrons that arise from antineutrino absorption by protons in the detector's ultrapure water are captured by gadolinium nuclei, which subsequently emit [[gamma ray]]s that are detected as part of the antineutrino signature.<ref name="Abe 2022">{{cite journal | last1=Abe | first1=K. | last2=Bronner | first2=C. | last3=Hayato | display-authors=etal | title=First gadolinium loading to Super-Kamiokande | journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | volume=1027 | year=2022 | issn=0168-9002 | doi=10.1016/j.nima.2021.166248 | article-number=166248| arxiv=2109.00360 | bibcode=2022NIMPA102766248A | s2cid=237372721 }}</ref>

[[Gadolinium gallium garnet]] (GGG, Gd<sub>3</sub>Ga<sub>5</sub>O<sub>12</sub>) was used for imitation diamonds and for computer [[bubble memory]].<ref name="CRC">Hammond, C. R. ''The Elements'', in {{RubberBible86th}}</ref>

==Safety==
{{Main|MRI contrast agent|Nephrogenic systemic fibrosis}}

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As a free ion, gadolinium is reported often to be highly toxic, but MRI contrast agents are [[chelation|chelated]] compounds and are considered safe enough to be used in most persons. The toxicity of free gadolinium ions in animals is due to interference with a number of calcium-ion channel dependent processes. The [[LD50|50% lethal dose]] is about 0.34&nbsp;mmol/kg (IV, mouse)<ref>Bousquet et coll., 1988</ref> or 100–200&nbsp;mg/kg. Toxicity studies in rodents show that chelation of gadolinium (which also improves its solubility) decreases its toxicity with regard to the free ion by a factor of 31 (i.e., the lethal dose for the Gd-chelate increases by 31 times).<ref>{{Cite web|url=https://www.acadpharm.org/dos_public/Academie_de_pharmacie_2014_JM_Idee_V2.pdf|title=Profil toxicologique des chélates de gadolinium pour l'IRM: où en est-on ?}}</ref><ref>{{Cite journal|last1=Ersoy|first1=Hale|last2=Rybicki|first2=Frank J.|date=November 2007|title=Biochemical Safety Profiles of Gadolinium-Based Extracellular Contrast Agents and Nephrogenic Systemic Fibrosis|journal=Journal of Magnetic Resonance Imaging |volume=26|issue=5|pages=1190–1197|doi=10.1002/jmri.21135|issn=1053-1807|pmc=2709982|pmid=17969161}}</ref><ref>{{cite journal |vauthors= Penfield JG, Reilly RF |title= What nephrologists need to know about gadolinium |journal= Nature Clinical Practice. Nephrology |volume= 3 |issue= 12 |pages= 654–68 |date= December 2007 |pmid= 18033225 |doi= 10.1038/ncpneph0660 |s2cid= 22435496 }}</ref> It is believed therefore that clinical toxicity of gadolinium-based contrast agents (GBCAs<ref name="GDD">{{cite web|url=https://gadoliniumtoxicity.com/tag/gadolinium-deposition-disease/|title=Gadolinium Deposition Disease (GDD) in Patients with Normal Renal Function|date=1 November 2015|website=Gadolinium Toxicity|access-date=3 February 2016}}</ref>) in humans will depend on the strength of the chelating agent; however this research is still not complete.{{When|date=August 2016}} About a dozen different Gd-chelated agents have been approved as MRI contrast agents around the world.<ref>{{cite web |url= http://www.ismrm.org/special/EMEA2.pdf |archive-url=https://web.archive.org/web/20071129121817/http://www.ismrm.org/special/EMEA2.pdf |archive-date=2007-11-29 |url-status=live|title= Questions and Answers on Magnetic resonance imaging |access-date= 6 June 2009|work=International Society for Magnetic Resonance in Medicine}}</ref><ref>{{cite web|title=Information on Gadolinium-Containing Contrast Agents |url=https://www.fda.gov/Cder/Drug/infopage/gcca/default.htm |work=US Food and Drug Administration |archive-url=https://web.archive.org/web/20080906211904/https://www.fda.gov/Cder/Drug/infopage/gcca/default.htm |archive-date=6 September 2008}}</ref><ref name="Gray">Gray, Theodore (2009). ''The Elements'', Black Dog & Leventhal Publishers, {{ISBN|1-57912-814-9}}.</ref>

Use of gadolinium-based contrast agents results in deposition of gadolinium in tissues of the brain, bone, skin, and other tissues in amounts that depend on [[Ultrafiltration (kidney)|kidney function]], structure of the chelates (linear or macrocyclic) and the dose administered.<ref name="Tweedle 2021">{{cite journal | last=Tweedle | first=Michael F. | title=Gadolinium Retention in Human Brain, Bone, and Skin | journal=Radiology | volume=300 | issue=3 | date=2021 | issn=0033-8419 | doi=10.1148/radiol.2021210957 | pages=570–571| pmid=34128728 }}</ref> In patients with kidney failure, there is a risk of a rare but serious illness called [[nephrogenic systemic fibrosis]] (NSF)<ref>{{cite journal |vauthors= Thomsen HS, Morcos SK, Dawson P |title= Is there a causal relation between the administration of gadolinium based contrast media and the development of nephrogenic systemic fibrosis (NSF)? |journal= Clinical Radiology |volume= 61 |issue= 11 |pages= 905–06 |date= November 2006 |pmid= 17018301 |doi= 10.1016/j.crad.2006.09.003 }}</ref> that is caused by the use of gadolinium-based contrast agents. The disease resembles [[scleromyxedema]] and to some extent [[scleroderma]]. It may occur months after a contrast agent has been injected. Its association with gadolinium and not the carrier molecule is confirmed by its occurrence with various contrast materials in which gadolinium is carried by very different carrier molecules. Because of the risk of NSF, use of these agents is not recommended for any individual with end-stage kidney failure as they may require emergent dialysis.

Included in the current guidelines from the Canadian Association of Radiologists<ref name="CARguidelines">{{cite journal |vauthors= Schieda N, Blaichman JI, Costa AF, Glikstein R, Hurrell C, James M, Jabehdar Maralani P, Shabana W, Tang A, Tsampalieros A, van der Pol CB, Hiremath S |title= Gadolinium-Based Contrast Agents in Kidney Disease: A Comprehensive Review and Clinical Practice Guideline Issued by the Canadian Association of Radiologists |journal= Canadian Journal of Kidney Health and Disease |volume= 5 |article-number= 2054358118778573 |date= 2018 |pmid= 29977584 |pmc= 6024496 |doi= 10.1177/2054358118778573}}</ref> are that dialysis patients should receive gadolinium agents only where essential and that they should receive dialysis after the exam. If a contrast-enhanced MRI must be performed on a dialysis patient, it is recommended that certain high-risk contrast agents be avoided but not that a lower dose be considered.<ref name="CARguidelines" /> The American College of Radiology recommends that contrast-enhanced MRI examinations be performed as closely before dialysis as possible as a precautionary measure, although this has not been proven to reduce the likelihood of developing NSF.<ref>{{cite book |author1=ACR Committee on Drugs |author2=Contrast Media |title= ACR Manual on Contrast Media Version 7 |date= 2010 |publisher=American College of Radiology |isbn= 978-1-55903-050-2}}</ref> The FDA recommends that potential for gadolinium retention be considered when choosing the type of GBCA used in patients requiring multiple lifetime doses, pregnant women, children, and patients with inflammatory conditions.<ref>{{cite web|url=https://www.fda.gov/Drugs/DrugSafety/ucm589213.htm|archive-url=https://web.archive.org/web/20180125050114/https://www.fda.gov/Drugs/DrugSafety/ucm589213.htm|archive-date=25 January 2018|publisher=Drug Safety and Availability – FDA Drug Safety Communication |title=FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings|author=Center for Drug Evaluation and Research|website=www.fda.gov|language=en|access-date=20 September 2018}}</ref>

[[Anaphylactoid reaction]]s are rare, occurring in approximately 0.03–0.1%.<ref>{{cite journal|vauthors=Murphy KJ, Brunberg JA, Cohan RH|date=October 1996|title=Adverse reactions to gadolinium contrast media: a review of 36 cases|journal=AJR. American Journal of Roentgenology|volume=167|issue=4|pages=847–49|doi=10.2214/ajr.167.4.8819369|pmid=8819369|doi-access=free}}</ref>

Long-term environmental impacts of gadolinium contamination due to human usage are a topic of ongoing research.<ref>{{cite journal|last1=Gwenzi|first1=Willis|last2=Mangori|first2=Lynda|last3=Danha|first3=Concilia|last4=Chaukura|first4=Nhamo|last5=Dunjana|first5=Nothando|last6=Sanganyado|first6=Edmond|date=15 September 2018|title=Sources, behaviour, and environmental and human health risks of high-technology rare-earth elements as emerging contaminants|journal=The Science of the Total Environment|volume=636|pages=299–313|doi=10.1016/j.scitotenv.2018.04.235|issn=1879-1026|pmid=29709849|bibcode=2018ScTEn.636..299G|s2cid=19076605}}</ref><ref>{{cite journal |vauthors= Rogowska J, Olkowska E, Ratajczyk W, Wolska L |title= Gadolinium as a new emerging contaminant of aquatic environments |journal= Environmental Toxicology and Chemistry |volume= 37 |issue= 6 |pages= 1523–34 |date= June 2018 |pmid= 29473658 |doi= 10.1002/etc.4116|doi-access= free |bibcode= 2018EnvTC..37.1523R }}</ref>

==Biological use==
Gadolinium has no known native biological role, but its compounds are used as research tools in biomedicine. Gd<sup>3+</sup> compounds are components of [[MRI contrast agent]]s.<ref>{{cite book|last1=Tircsó|first1=Gyulia|title=Metal Ions in Bio-Imaging Techniques|last2=Molńar|first2=Enricő|last3=Csupász|first3=Tibor|last4=Garda|first4=Zoltan|last5=Botár|first5=Richárd|last6=Kálmán|first6=Ferenc K.|last7=Kovács|first7=Zoltan|last8=Brücher|first8=Ernő|last9=Tóth|first9=Imre|publisher=Springer|year=2021|pages=39–70|chapter=Chapter 2. Gadolinium(III)-Based Contrast Agents for Magnetic Resonance Imaging. A Re-Appraisal|doi=10.1515/9783110685701-008|isbn=978-3-11-068570-1 |s2cid=233702931}}</ref> It is used in various [[ion channel]] electrophysiology experiments to block sodium leak channels and stretch activated ion channels.<ref>{{cite journal|vauthors=Yeung EW, Allen DG|date=August 2004|title=Stretch-activated channels in stretch-induced muscle damage: role in muscular dystrophy|journal=Clinical and Experimental Pharmacology & Physiology|volume=31|issue=8|pages=551–56|doi=10.1111/j.1440-1681.2004.04027.x|pmid=15298550|hdl-access=free|hdl=10397/30099|s2cid=9550616}}</ref> Gadolinium has recently been used to measure the distance between two points in a protein via [[electron paramagnetic resonance]], something that gadolinium is especially amenable to thanks to EPR sensitivity at w-band (95&nbsp;GHz) frequencies.<ref>{{cite journal|vauthors=Yang Y, Yang F, Gong Y, Bahrenberg T, Feintuch A, Su X, Goldfarb, D|date=October 2018|title=High Sensitivity In-Cell EPR Distance Measurements on Proteins using and Optimized Gd(III) Spin Label|journal=The Journal of Physical Chemistry Letters|volume=9|issue=20|pages=6119–23|doi=10.1021/acs.jpclett.8b02663|pmid=30277780|bibcode=2018JPCL....9.6119Y |s2cid=52909932}}</ref>

==Notes==
{{notelist}}

==References==
{{Reflist|30em|refs=
<ref name="r27">{{cite journal|author=Gschneidner, K. |author2=Pecharsky, V. |author3=Tsokol, A. |doi=10.1088/0034-4885/68/6/R04 |url=http://www.teknik.uu.se/ftf/education/magnetmatr/Projektreferenser/MCE_Reports_Progress05.pdf |title=Recent Developments in Magnetocaloric Materials |date=2005 |journal=Reports on Progress in Physics |volume=68 |issue=6 |page=1479 |bibcode=2005RPPh...68.1479G |s2cid=56381721 |archive-url=https://web.archive.org/web/20141109081936/http://www.teknik.uu.se/ftf/education/magnetmatr/Projektreferenser/MCE_Reports_Progress05.pdf |archive-date=9 November 2014 }}</ref>
}}

==External links==
{{Commons}}
{{Wiktionary|gadolinium}}
* [https://web.archive.org/web/20070927220031/http://rad.usuhs.edu/medpix/master.php3?mode=slide_sorter&pt_id=10978&quiz=#top Nephrogenic Systemic Fibrosis – Complication of Gadolinium MR Contrast] (series of images at MedPix website)
* [https://education.jlab.org/itselemental/ele064.html It's Elemental – Gadolinium]
* [https://web.archive.org/web/20100323011159/http://www.external.ameslab.gov/news/release/01magneticrefrig.htm Refrigerator uses gadolinium metal that heats up when exposed to magnetic field]
* [https://web.archive.org/web/20090309174807/https://www.fda.gov/cder/drug/infopage/gcca/qa_200705.htm FDA advisory on gadolinium-based contrast]
* [http://www.siaecm.org/gadolinium/index.asp Abdominal MR imaging: important considerations for evaluation of gadolinium enhancement] {{Webarchive|url=https://web.archive.org/web/20120227030527/http://www.siaecm.org/gadolinium/index.asp |date=27 February 2012 }} Rafael O.P. de Campos, Vasco Herédia, Ersan Altun, Richard C. Semelka, Department of Radiology University of North Carolina Hospitals Chapel Hill
* [https://mobile.abc.net.au/news/2019-06-17/inside-super-kamiokande-360-tour/11209104 Inside Japan's Super Kamiokande 360 degree tour including details on adding Gadolinium to the pure water to aid in studying neutrinos]
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[[Category:Gadolinium| ]]
[[Category:Chemical elements]]
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[[Category:Lanthanides]]
[[Category:Neutron poisons]]
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