Editing Gadolinium (section)

==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|pages= 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 |pages=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 |url-status=dead |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 |url=https://doi.org/10.1007/BF02652955 |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|pages=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|pages=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|pages=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|pages=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|pages=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 | page=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>