View source for Yttrium barium copper oxide

{{chembox
| Watchedfields  = changed
| verifiedrevid  = 432929974
| Name           = Yttrium barium copper oxide
| ImageFile      = BaYCusuperconduct.jpg
| ImageSize      = 
| ImageName      = Yttrium barium copper oxide structure
| ImageFile2     = YBCO superconductor.JPG
| ImageSize2     = 
| ImageName2     = Yttrium barium copper oxide crystal
| IUPACName      = barium copper yttrium oxide
| OtherNames     = YBCO, Y123, yttrium barium cuprate
| Section1       = {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 107539-20-8
| ChemSpiderID = 17339938
| EINECS = 619-720-7
| PubChem = 21871996
 }}
| Section2       = {{Chembox Properties
| Formula = YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>
| MolarMass = 666.19 g/mol
| Appearance = Black solid
| Density = 6.4 g/cm<sup>3</sup><ref>{{cite journal|doi=10.1016/S0921-4534(03)01311-X|title=Interrelation of preparation conditions, morphology, chemical reactivity and homogeneity of ceramic YBCO|year=2003|last1=Knizhnik|first1=A|journal=Physica C: Superconductivity|volume=400|issue=1–2|page=25|bibcode = 2003PhyC..400...25K }}</ref><ref>{{cite journal|doi=10.1016/S0921-4534(99)00423-2|title=Growth mode study of ultrathin HTSC YBCO films on YBaCuNbO buffer|year=1999|last1=Grekhov|first1=I|journal=Physica C: Superconductivity|volume=324|issue=1|page=39|bibcode = 1999PhyC..324...39G |doi-access=free}}</ref>
| Solubility = Insoluble
| MeltingPt = >1000 °C
 }}
| Section3       = {{Chembox Structure
| Coordination = [[Orthorhombic]]
| CrystalStruct = Based on the [[perovskite (structure)|perovskite structure]].
 }}
| Section7       = {{Chembox Hazards
| GHSPictograms = {{GHS07}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|302|315|319|335}}
| PPhrases = {{P-phrases|261|264|270|271|280|301+312|302+352|304+340|305+351+338|312|321|330|332+313|337+313|362|403+233|405|501}}
 }}
| Section8       = {{Chembox Related
| OtherFunction_label = [[High-temperature superconductor|high-''T''<sub>c</sub><br />superconductors]]
| OtherFunction = Cuprate superconductors
| OtherCompounds = [[Yttrium(III) oxide]]<br />[[Barium oxide]]<br />[[Copper(II) oxide]]
}}
}}

'''Yttrium barium copper oxide''' ('''YBCO''') is a family of [[crystal]]line [[chemical compound]]s that display [[high-temperature superconductivity]]; it includes the first material ever discovered to become [[superconductivity|superconducting]] above the boiling point of [[liquid nitrogen]] [{{Convert|77|K|C F}}] at about {{Convert|93|K|C F}}.<ref name=":0" />

Many YBCO compounds have the general formula {{Chem2|[[Yttrium|Y]][[Barium|Ba]]2[[Copper|Cu]]3[[Oxygen|O]]_{7-''x''} }} (also known as Y123), although materials with other Y:Ba:Cu ratios exist, such as {{Chem2|[[Yttrium|Y]][[Barium|Ba]]2[[Copper|Cu]]4[[Oxygen|O]]_{''y''} }} (Y124) or {{Chem2|[[Yttrium|Y]]2[[Barium|Ba]]4[[Copper|Cu]]7[[Oxygen|O]]_{''y''} }} (Y247). At present, there is no singularly recognised theory for high-temperature superconductivity.

It is part of the more general group of [[rare-earth barium copper oxide]]s (ReBCO) in which, instead of yttrium, other rare earths are present.

==History==
In April 1986, [[Georg Bednorz]] and [[Karl Alexander Müller|Karl Müller]], working at [[IBM Research – Zurich|IBM in Zurich]], discovered that certain semiconducting oxides became superconducting at relatively high temperature, in particular, a [[lanthanum barium copper oxide]] becomes superconducting at 35&nbsp;K. This oxide was an [[oxygen-deficient compound|oxygen-deficient]] [[perovskite]]-related material that proved promising and stimulated the search for related compounds with higher superconducting transition temperatures. In 1987, Bednorz and Müller were jointly awarded the Nobel Prize in Physics for this work.

Following Bednorz and Müller's discovery, a team led by [[Paul Ching Wu Chu]] at the [[University of Alabama in Huntsville]] and [[University of Houston]] discovered that YBCO has a superconducting transition critical temperature (''T''<sub>c</sub>) of 93 K.<ref name=":0">{{cite journal|title = Superconductivity at 93 K in a New Mixed-Phase Y-Ba-Cu-O Compound System at Ambient Pressure|journal = Physical Review Letters|year = 1987|volume = 58|pages = 908–910|doi = 10.1103/PhysRevLett.58.908|pmid = 10035069|issue = 9|bibcode=1987PhRvL..58..908W|last1 = Wu|first1 = M. K.|last2 = Ashburn|first2 = J. R.|last3 = Torng|first3 = C. J.|last4 = Hor|first4 = P. H.|last5 = Meng|first5 = R. L.|last6 = Gao|first6 = L|last7 = Huang|first7 = Z. J.|last8 = Wang|first8 = Y. Q.|last9 = Chu|first9 = C. W.|doi-access = free}}</ref> The first samples were [[Yttrium|Y]]<sub>1.2</sub>[[Barium|Ba]]<sub>0.8</sub>[[Copper|Cu]][[Oxygen|O]]<sub>4</sub>, but this was an average composition for two phases, a black and a green one. Workers at [[Bell Laboratories]]  identified the black phase as the superconductor, determined its composition YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−δ</sub> and synthesized it in single phase<ref>R. J. Cava, B. Batlogg, R. B. van Dover, D. W. Murphy, S. Sunshine, T. Siegrist, J. P. Remeika, E. A. Rietman, S. Zahurak, and G. P. Espinosa, Physical Review Letters 58, 1676 (1987),  subm. March 5, 1987,  "Bulk superconductivity at 91 K in single-phase oxygen-deficient perovskite Ba2YCu3O9−δ" /    and US patent 6,6635,603  (B. J. Batlogg, R. J. Cava, R. B. van Dover ),  Macilwain, C.   Bell Labs win superconductivity patent. Nature 403, 121–122 (2000). https://doi.org/10.1038/35003008 |

</ref>

YBCO was the first material found to become superconducting above 77&nbsp;K, the boiling point of [[liquid nitrogen]], whereas the majority of other superconductors require more expensive cryogens.  Nonetheless, YBCO and its many related materials have yet to displace superconductors requiring [[liquid helium]] for cooling.

==Synthesis==
Relatively pure YBCO was first synthesized by heating a mixture of the metal carbonates at temperatures between 1000 and 1300 K.<ref name="hous">{{Housecroft2nd}}</ref><ref name="earnshaw">{{Greenwood&Earnshaw2nd}}</ref>

:4 BaCO<sub>3</sub> + Y<sub>2</sub>(CO<sub>3</sub>)<sub>3</sub> + 6 CuCO<sub>3</sub> + ({{1/2}}−''x'') O<sub>2</sub> → 2 YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−''x''</sub> + 13 CO<sub>2</sub>

Modern syntheses of YBCO use the corresponding oxides and nitrates.<ref name=earnshaw />

The superconducting properties of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−''x''</sub> are sensitive to the value of ''x'', its oxygen content. Only those materials with {{math|0 ≤ ''x'' ≤ 0.65}} are superconducting below ''T''<sub>c</sub>, and when {{math|''x'' ~ 0.07}}, the material superconducts at the highest temperature of {{val|95|u=K}},<ref name=earnshaw /> or in highest magnetic fields: {{val|120|ul=T}} for '''B''' perpendicular and {{val|250|u=T}} for '''B''' parallel to the CuO<sub>2</sub> planes.<ref>{{cite journal|doi=10.1016/j.physb.2004.01.098|title = Upper critical field for optimally-doped YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−δ</sub> |journal = Physica B: Condensed Matter |volume = 346–347 |pages = 319–324 |year = 2004 |last1 = Sekitani |first1 = T. |last2 = Miura |first2 = N. |last3 = Ikeda |first3 = S. |last4 = Matsuda |first4 = Y.H. |last5 = Shiohara |first5 = Y. |bibcode = 2004PhyB..346..319S }}</ref>

In addition to being sensitive to the stoichiometry of oxygen, the properties of YBCO are influenced by the crystallization methods used. Care must be taken to [[sintering|sinter]] YBCO. YBCO is a crystalline material, and the best superconductive properties are obtained when crystal [[Grain boundary|grain boundaries]] are aligned by careful control of [[Annealing (metallurgy)|annealing]] and [[quenching]] temperature rates.

Numerous other methods to synthesize YBCO have developed since its discovery by Wu and his co-workers, such as [[chemical vapor deposition]] (CVD),<ref name="hous" /><ref name=earnshaw /> [[sol-gel]],<ref>{{cite journal|author1=Sun, Yang-Kook  |author2=Oh, In-Hwan  |name-list-style=amp |journal=Ind. Eng. Chem. Res.|year=1996|volume=35|page=4296|title=Preparation of Ultrafine YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−x</sub> Superconductor Powders by the Poly(vinyl alcohol)-Assisted Sol−Gel Method|doi=10.1021/ie950527y|issue=11}}</ref> and [[aerosol]]<ref>{{cite journal|title = Yttrium Barium Copper Oxide Superconducting Powder Generation by An Aerosol Process|author = Zhou, Derong|publisher = University of Cincinnati|year = 1991|bibcode = 1991PhDT........28Z|page = 28}}</ref> methods. These alternative methods, however, still require careful sintering to produce a quality product.

However, new possibilities have been opened since the discovery that trifluoroacetic acid ([[Trifluoroacetic acid|TFA]]), a source of fluorine, prevents the formation of the undesired [[barium carbonate]] (BaCO<sub>3</sub>). Routes such as CSD (chemical solution deposition) have opened a wide range of possibilities, particularly in the preparation of long YBCO tapes.<ref>{{cite journal|title = High quality YBa<sub>2</sub>Cu<sub>3</sub>O<sub>{7–''x''}</sub> thin films grown by trifluoroacetates metal-organic deposition|year = 2003|journal =Supercond. Sci. Technol.|volume = 16|pages = 45–53|doi = 10.1088/0953-2048/16/1/309|bibcode = 2003SuScT..16...45C |last1 = Casta o|first1 = O|last2 = Cavallaro|first2 = A|last3 = Palau|first3 = A|last4 = Gonz Lez|first4 = J C|last5 = Rossell|first5 = M|last6 = Puig|first6 = T|last7 = Sandiumenge|first7 = F|last8 = Mestres|first8 = N|last9 = Pi Ol|first9 = S|last10 = Pomar|first10 = A|last11 = Obradors|first11 = X|issue = 1| s2cid=250765145 }}</ref> This route lowers the temperature necessary to get the correct phase to around {{Convert|700|C|K F}}. This, and the lack of dependence on vacuum, makes this method a very promising way to get scalable YBCO tapes.

==Structure==
[[Image:Ybco002.svg|thumb|Part of the lattice structure of yttrium barium copper oxide]]
YBCO crystallizes in a [[defect perovskite structure]]. It can be viewed as a layered structure: the boundary of each layer is defined by planes of square planar CuO<sub>4</sub> units sharing 4 vertices. The planes can sometimes be slightly puckered.<ref name="hous" /> Perpendicular to these CuO<sub>4</sub> planes are CuO<sub>2</sub> ribbons sharing 2 vertices. The [[yttrium]] atoms are found between the CuO<sub>4</sub> planes, while the [[barium]] atoms are found between the CuO<sub>2</sub> ribbons and the CuO<sub>4</sub> planes. This structural feature is illustrated in the figure to the right.

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ [[Coordination geometry]] of metal centres in YBCO<ref>{{ cite journal | first1 = A. | last1 = Williams | first2 = G. H. | last2 = Kwei | first3 = R. B. | last3 = Von Dreele | first4 = I. D. | last4 = Raistrick | first5 = D. L. | last5 = Bish | title = Joint x-ray and neutron refinement of the structure of superconducting YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7&minus;x</sub>: Precision structure, anisotropic thermal parameters, strain, and cation disorder | journal = [[Physical Review B|Phys. Rev. B]] | volume = 37 | year = 1988 | issue = 13 | pages = 7960–7962 | doi = 10.1103/PhysRevB.37.7960 | pmid = 9944122 }}</ref><ref name="earnshaw" />
|[[File:YBCO-xtal-Y-coordination-3D-bs-17.png|150px]]||[[File:YBCO-xtal-Ba-coordination-3D-bs-17.png|150px]]||[[File:YBCO-xtal-Cu1-coordination-3D-bs-17.png|120px]]||[[File:YBCO-xtal-Cu2-coordination-3D-bs-17.png|120px]]||[[File:YBCO-xtal-unit-cell-3D-bs-17-atoms-labelled.png|100px]]
|-
|cubic {YO<sub>8</sub>}||{BaO<sub>10</sub>}||[[Square planar molecular geometry|square planar]] {CuO<sub>4</sub>}||[[Square pyramidal molecular geometry|square pyramidal]] {CuO<sub>5</sub>}||{{vanchor|Unit cell|text=YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-<math>\delta</math></sub> unit cell}}
|}

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+ 
|[[File:YBCO-xtal-puckered-Cu2-plane-3D-bs-17.png|250px]]||[[File:YBCO-xtal-flat-Cu1-ribbons-3D-bs-17.png|200px]]
|-
|puckered Cu plane||Cu ribbons
|}

[[File:Flyingsuperconductor.ogg|thumb|Like many [[type-II superconductor]]s, YBCO can exhibit [[flux pinning]]: lines of magnetic flux may be pinned in place in a crystal, with a force required to move a piece from a particular magnetic field configuration. A piece of YBCO placed above a magnetic track can thus levitate at a fixed height.<ref name="hous" />]]
Although YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> is a well-defined chemical compound with a specific structure and stoichiometry, materials with fewer than seven oxygen atoms per formula unit are [[non-stoichiometric compound]]s. The structure of these materials depends on the oxygen content. This non-stoichiometry is denoted by the x in the chemical formula YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−''x''</sub>. When ''x'' = 1, the O(1) sites in the Cu(1) layer (as labelled in [[#Unit Cell|the unit cell]]) are vacant and the structure is [[tetragonal]]. The tetragonal form of YBCO is insulating and does not superconduct. Increasing the oxygen content slightly causes more of the O(1) sites to become occupied. For ''x'' < 0.65, Cu-O chains along the ''b'' axis of the crystal are formed. Elongation of the ''b'' axis changes the structure to [[orthorhombic]], with lattice parameters of ''a'' = 3.82, ''b'' = 3.89, and ''c'' = 11.68 Å.<ref name="MookPolarized1993">{{cite journal |last1=Mook |first1=H. A. |title=Polarized Neutron Determination of the Magnetic Excitations in YBa2Cu3O7 |journal=Physical Review Letters |date=31 May 1993 |volume=70 |issue=22 |pages=3490–3493 |doi=10.1103/PhysRevLett.70.3490|pmid=10053882 }}</ref> Optimum superconducting properties occur when ''x'' ~ 0.07, i.e., almost all of the O(1) sites are occupied, with few vacancies.

In experiments where other elements are substituted on the Cu and Ba{{why||date=September 2014}} sites, evidence has shown that conduction occurs in the Cu(2)O planes while the Cu(1)O(1) chains act as charge reservoirs, which provide carriers to the CuO planes. However, this model fails to address superconductivity in the homologue Pr123 ([[praseodymium]] instead of yttrium).<ref>{{cite journal|journal=Physica C|volume=300|issue=3–4|year=1998|page=200|doi=10.1016/S0921-4534(98)00130-0|title=Crystal growth of superconductive PrBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−y</sub>|last1=Oka|first1=K|bibcode = 1998PhyC..300..200O }}</ref> This (conduction in the copper planes) confines conductivity to the ''a''-''b'' planes and a large anisotropy in transport properties is observed. Along the ''c'' axis, normal conductivity is 10 times smaller than in the ''a''-''b'' plane. For other [[Cuprate superconductor|cuprate]]s in the same general class, the anisotropy is even greater and inter-plane transport is highly restricted.

Furthermore, the superconducting length scales show similar anisotropy, in both penetration depth (λ<sub>ab</sub> ≈ 150&nbsp;nm, λ<sub>c</sub> ≈ 800&nbsp;nm) and coherence length, (ξ<sub>ab</sub> ≈ 2&nbsp;nm, ξ<sub>c</sub> ≈ 0.4&nbsp;nm). Although the coherence length in the ''a''-''b'' plane is 5 times greater than that along the ''c'' axis it is quite small compared to classic superconductors such as niobium (where ξ ≈ 40&nbsp;nm). This modest coherence length means that the superconducting state is more susceptible to local disruptions from interfaces or defects on the order of a single unit cell, such as the boundary between twinned crystal domains. This sensitivity to small defects complicates fabricating devices with YBCO, and the material is also sensitive to degradation from humidity.

==Proposed applications==
[[File:YBCO-IG A vs T.svg|left|thumb|Critical current (KA/cm<sup>2</sup>) vs absolute temperature (K), at different intensity of magnetic field (T) in YBCO prepared by infiltration-growth.<ref>{{Cite journal|last1=Koblischka-Veneva|first1=Anjela|last2=Koblischka|first2=Michael R.|last3=Berger|first3=Kévin|last4=Nouailhetas|first4=Quentin|last5=Douine|first5=Bruno|last6=Muralidhar|first6=Miryala|last7=Murakami|first7=Masato|date=August 2019|title=Comparison of Temperature and Field Dependencies of the Critical Current Densities of Bulk YBCO, MgB₂, and Iron-Based Superconductors|url=https://ieeexplore.ieee.org/document/8649756|journal=IEEE Transactions on Applied Superconductivity|volume=29|issue=5|pages=1–5|doi=10.1109/TASC.2019.2900932|bibcode=2019ITAS...2900932K |s2cid=94789535 |issn=1558-2515}}</ref>]]
Many possible applications of this and related high temperature superconducting materials have been discussed. For example, superconducting materials are finding use as [[superconducting magnets|magnets]] in [[magnetic resonance imaging]], [[magnetic levitation]], and [[Josephson junction]]s. (The most used material for power cables and magnets is [[BSCCO]].){{Citation needed|date=October 2021}}

YBCO has yet to be used in many applications involving superconductors for two primary reasons:
*First, although single crystals of YBCO have a very high critical current density, [[polycrystal]]s have a very low critical [[current density]]: only a small current can be passed while maintaining superconductivity. This problem is due to crystal [[grain boundaries]] in the material. When the grain boundary angle is greater than about 5°, the supercurrent cannot cross the boundary. The grain boundary problem can be controlled to some extent by preparing thin films via [[Chemical vapor deposition|CVD]] or by texturing the material to align the grain boundaries.{{Citation needed|date=October 2021}}
*A second problem limiting the use of this material in technological applications is associated with processing of the material. Oxide materials such as this are brittle, and forming them into [[superconducting wire]]s by any conventional process does not produce a useful superconductor. (Unlike [[BSCCO]], the [[powder-in-tube]] process does not give good results with YBCO.){{Citation needed|date=October 2021}}
The most promising method developed to utilize this material involves deposition of YBCO on flexible metal tapes coated with buffering metal oxides. This is known as {{em|coated conductor}}. Texture (crystal plane alignment) can be introduced into the metal tape (the RABiTS process) or a textured ceramic buffer layer can be deposited, with the aid of an ion beam, on an untextured alloy substrate (the [[IBAD]] process). Subsequent oxide layers prevent diffusion of the metal from the tape into the superconductor while transferring the template for texturing the superconducting layer. Novel variants on CVD, PVD, and solution deposition techniques are used to produce long lengths of the final YBCO layer at high rates. Companies pursuing these processes include [[American Superconductor]], Superpower (a division of [[Furukawa Electric]]), [[Sumitomo]], [[Fujikura]], [[Nexans]] Superconductors, [[Commonwealth Fusion Systems]], and European Advanced Superconductors. A much larger number of research institutes have also produced YBCO tape by these methods.{{Citation needed|date=October 2021}}

The superconducting tape is used for [[SPARC (tokamak)|SPARC]], a [[tokamak]] fusion reactor design that can achieve [[Fusion energy gain factor|breakeven]] energy production.<ref>{{Cite web |last=McFadden |first=Christopher |title=A special new tape could make small, efficient nuclear fusion reactors possible |url=https://interestingengineering.com/innovation/new-tape-nuclear-fusion-reactors |access-date=2025-01-07 |website=Interesting Engineering |language=en}}</ref>

==Surface modification==
Surface modification of materials has often led to new and improved properties. Corrosion inhibition, polymer adhesion and nucleation, preparation of organic superconductor/insulator/high-''T''<sub>c</sub> superconductor trilayer structures, and the fabrication of metal/insulator/superconductor tunnel junctions have been developed using surface-modified YBCO.<ref>{{cite journal|journal=Langmuir|year=1998|volume=14|issue=22|title=Surface Coordination Chemistry of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−δ</sub> |author=Xu, F. |page=6505|doi=10.1021/la980143n|display-authors=etal}}</ref>

These molecular layered materials are synthesized using [[cyclic voltammetry]]. Thus far, YBCO layered with alkylamines, arylamines, and [[thiol]]s have been produced with varying stability of the molecular layer. It has been proposed that amines act as [[Lewis bases]] and bind to [[Lewis acids and bases|Lewis acidic]] Cu surface sites in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> to form stable [[coordination bond]]s.

==Mass production==
[[File:SuperOX_Wire_Production_from_2013_to_2021.png|thumbnail|upright=1.5|SuperOx was able to produce over 186 miles of YBCO in 9 months for use in a fusion magnet.]]
In 1987, shortly after it was discovered, physicist and science author [[Paul Grant (physicist)|Paul Grant]] published in the U.K. Journal ''[[New Scientist]]'' a straightforward guide for synthesizing YBCO superconductors using widely-available equipment.<ref>{{cite journal |last1=Grant |first1=Paul |date=30 July 1987 |title=Do-it-yourself Superconductors |url=https://books.google.com/books?id=Qe_hJ8qZb7oC&pg=PA36 |journal=New Scientist |language=en |publisher=Reed Business Information |volume=115 |issue=1571 |page=36 |access-date=12 January 2019}}</ref> Thanks in part to this article and similar publications at the time, YBCO has become a popular high-temperature superconductor for use by hobbyists and in education, as the magnetic levitation effect can be easily demonstrated using liquid nitrogen as coolant.

In 2021, SuperOx, a Russian and Japanese company, developed a new manufacturing process for making YBCO wire for fusion reactors.  This new wire was shown to conduct between 700 and 2000 Amps per square millimeter. The company was able to produce 186 miles of wire in 9 months, between 2019 and 2021, dramatically improving the production capacity.  The company used a plasma-laser deposition process, on a electropolished substrate to make 12-mm width tape and then slit it into 3-mm tape.<ref>{{cite journal|journal=Scientific Reports|year=2021|volume=11|article-number=2084|author1=Molodyk, A.|title=Development and large volume production of extremely high current density YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> superconducting wires for fusion|issue=1 |page=2084 |doi=10.1038/s41598-021-81559-z|display-authors=etal|doi-access=free|pmid=33483553 |pmc=7822827}}</ref>

==References==
{{reflist|30em}}

==External links==
{{Commons category}}
*[http://www.ch.ic.ac.uk/otway/YBCO.html Diagram of YBCO structure]
*{{Cite journal |last1=Djurovich |first1=Peter I. |last2=Watts |first2=Richard J. |date=June 1993 |title=A simple and reliable chemical preparation of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−''x''</sub> superconductors |url= |journal=Journal of Chemical Education |language=en |volume=70 |issue=6 |pages=497 |doi=10.1021/ed070p497 |issn=0021-9584}}
*[https://www.youtube.com/watch?v=RS7gyZJg5nc Synthesis of YBCO using somewhat common lab equipment] - [[NileRed]]
*[http://www.physorg.com/news105718161.html New World Record For Superconducting Magnet 26.8T April 2007]
*[http://www.futurescience.com/manual/ybcomsds.html External MSDS Data Sheet (safety classifications) for YBCO].
*[http://www.superlife.info Superconductivity in everyday life : Interactive exhibition – little if any specific to YBCO] {{Webarchive|url=https://web.archive.org/web/20051205121000/http://www.superlife.info/ |date=2005-12-05 }}.

{{yttrium compounds}}
{{barium compounds}}
{{copper compounds}}
{{oxides}}

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