Misplaced Pages

Yttrium barium copper oxide: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively
Page 1
Page 2
← Previous editContent deleted Content addedVisualWikitext
Revision as of 22:43, 6 June 2011 editLambda(T) (talk | contribs)242 edits Nitrogen to liquid nitrogen (w/ boiling point) in introduction and history section; perovskite -> "perovskite structure" link in table← Previous edit Latest revision as of 19:38, 12 October 2024 edit undoCitation bot (talk | contribs)Bots5,424,960 edits Add: pmid, authors 1-1. Removed parameters. Some additions/deletions were parameter name changes. | Use this bot. Report bugs. | Suggested by Abductive | Category:High-temperature superconductors | #UCB_Category 12/13 
(217 intermediate revisions by more than 100 users not shown)
Line 1: Line 1:
{{chembox {{chembox
| Watchedfields = changed | Watchedfields = changed
| verifiedrevid = 411344157 | verifiedrevid = 432929974
| Name = Yttrium barium copper oxide | Name = Yttrium barium copper oxide
| ImageFile = BaYCusuperconduct.jpg | ImageFile = BaYCusuperconduct.jpg
| ImageSize = 200px | ImageSize =
| ImageName = Yttrium barium copper oxide | ImageName = Yttrium barium copper oxide structure
| ImageFile2 = YBCO superconductor.JPG
| IUPACName = barium copper yttrium oxide
| ImageSize2 =
| OtherNames = YBCO, Y123,<br />yttrium barium cuprate
| ImageName2 = Yttrium barium copper oxide crystal
| Section1 = {{Chembox Identifiers
| IUPACName = barium copper yttrium oxide
| CASNo_Ref = {{cascite}}
| OtherNames = YBCO, Y123, yttrium barium cuprate
| Section1 = {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 107539-20-8 | CASNo = 107539-20-8
| ChemSpiderID = 17339938
}}
| EINECS = 619-720-7
| Section2 = {{Chembox Properties
| PubChem = 21871996
}}
| Section2 = {{Chembox Properties
| Formula = YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> | Formula = YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>
| MolarMass = 666.19 | MolarMass = 666.19 g/mol
| Appearance = Black solid | Appearance = Black solid
| Density = 6.3 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|pages=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|pages=39|bibcode = 1999PhyC..324...39G }}</ref> | 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 | Solubility = Insoluble
| MeltingPt = >1000 °C | MeltingPt = >1000 °C
}}
| Critical Field = 120 T (CuO2 perpendicular) 250 T (parallel)
| Section3 = {{Chembox Structure
}}
| Section3 = {{Chembox Structure
| Coordination = ] | Coordination = ]
| CrystalStruct = Based on the ]. | CrystalStruct = Based on the ].
}} }}
| Section7 = {{Chembox Hazards | Section7 = {{Chembox Hazards
| GHSPictograms = {{GHS07}}
| EUClass = Irritant ('''Xi''')
| GHSSignalWord = Warning
}}
| HPhrases = {{H-phrases|302|315|319|335}}
| Section8 = {{Chembox Related
| 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}}
| Function = ]
}}
| OtherFunctn = BaLaO<sub>3-x</sub>
| Section8 = {{Chembox Related
| OtherCpds = ]<br />]<br />]
| OtherFunction_label = ]
| OtherFunction = Cuprate superconductors
| OtherCompounds = ]<br />]<br />]
}} }}
}} }}


'''Yttrium barium copper oxide''', often abbreviated YBCO, is a ]line ] with the formula ]]<sub>2</sub>]<sub>3</sub>]<sub>7</sub>. This material, a famous "]", achieved prominence because it was the first material to achieve ] above the boiling point (77 ]) of ]. '''Yttrium barium copper oxide''' ('''YBCO''') is a family of ]line ]s that display ]; it includes the first material ever discovered to become ] above the boiling point of ] at about {{Convert|93|K|C F}}.<ref name=":0" />

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

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


==History== ==History==
In April 1986 (seventy-five years after the discovery of superconductivity in 1911), ] and ], working at ] in ], discovered that certain semiconducting oxides became ] at 35&nbsp;K, then considered a relatively high temperature. In particular, the lanthanum barium copper oxides, an oxygen deficient ]-related material, proved promising. In 1987, Bednorz and Müller were jointly awarded the Nobel Prize in Physics for this work. In April 1986, ] and ], working at ], discovered that certain semiconducting oxides became superconducting at relatively high temperature, in particular, a ] becomes superconducting at 35&nbsp;K. This oxide was an ] ]-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.


Building on that, ] and his graduate students, Ashburn and Torng<ref>{{cite journal|author = M. K. Wu, J. R. Ashburn, C. J. Torng, P. H. Hor, R. L. Meng, L. Gao, Z. J. Huang, Y. Q. Wang, and C. W. Chu|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}}</ref> at the ] in 1987, and ] and his students at the ] in 1987 (see ] page for info), discovered YBCO has a ] of 93 K. Following Bednorz and Müller's discovery, a team led by ] at the ] and ] 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 ]<sub>1.2</sub>]<sub>0.8</sub>]]<sub>4</sub>, but this was an average composition for two phases, a black and a green one. Workers at ] 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 |
(The first samples were ]<sub>1.2</sub>]<sub>0.8</sub>]]<sub>4</sub>.) Their work led to a rapid succession of new high temperature superconducting materials, ushering in a new era in material science and chemistry.


</ref>
YBCO was the first material to become superconducting above 77 K, the boiling point of ]. All materials developed before 1986 became superconducting only at temperatures near the boiling points of ] (''T''<sub>b</sub>&nbsp;= 4.2 K) or ] (''T''<sub>b</sub>&nbsp;= 20.28 K) — the highest being Nb<sub>3</sub>Ge at 23 K. The significance of the discovery of YBCO is the much lower cost of the refrigerant used to cool the material to below the ].

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


==Synthesis== ==Synthesis==
Relatively pure YBCO was first synthesized by heating a mixture of the metal carbonates at temperatures between 1000 to 1300 K.<ref name=hous>{{Housecroft2nd}}</ref><ref name=earnshaw>{{Greenwood&Earnshaw2nd}}</ref> 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&minus;''x'') O<sub>2</sub> → 2 YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7&minus;''x''</sub> + 13 CO<sub>2</sub> :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 /> 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&minus;''x''</sub> are sensitive to the value of ''x'', its oxygen content. Only those materials with 0&nbsp;≤ ''x''&nbsp;≤ 0.65 are superconducting below ''T''<sub>c</sub>, and when ''x''&nbsp;~ 0.07 the material superconducts at the highest temperature of 95 K,<ref name=earnshaw /> or in highest magnetic fields: 120 ] for '''B''' perpendicular and 250 T for '''B''' parallel to the CuO<sub>2</sub> planes.<ref>{{cite web|author = T. Sekitania, N. Miura, S. Ikedaa, Y. H. Matsudaa, Y. Shioharab|title = Upper critical field for optimally-doped YBa2Cu3O7−δ|publisher = Elsevier Science B.V.|year = 2004|url = http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVH-4BWYV0D-H&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=28aeb1ca959e86bc4a201f483224ec06}}</ref> 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 ] YBCO. YBCO is a crystalline material, and the best superconductive properties are obtained when crystal grain boundaries are aligned by careful control of ] and ] temperature rates. 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 ] YBCO. YBCO is a crystalline material, and the best superconductive properties are obtained when crystal ] are aligned by careful control of ] and ] temperature rates.


Numerous other methods to synthesize YBCO have developed since its discovery by Wu and his coworkers, such as ] (CVD),<ref name="hous" /><ref name=earnshaw /> ],<ref>{{cite journal|author=Yang-Kook Sun, In-Hwan Oh|journal=Ind. Eng. Chem. Res.|year=1996|volume=35|page=4296|title=Preparation of Ultrafine YBa2Cu3O7-x Superconductor Powders by the Poly(vinyl alcohol)-Assisted Sol−Gel Method|doi=10.1021/ie950527y}}</ref> and ]<ref>{{cite web|title = Yttrium Barium Copper Oxide Superconducting Powder Generation by An Aerosol Process|author = Zhou, Derong|publisher = University of Cincinnati|format = Ph.D. Thesis|year = 1991|url = http://adsabs.harvard.edu/abs/1991PhDT........28Z}}</ref> methods. These alternative methods, however, still require careful sintering to produce a quality product. Numerous other methods to synthesize YBCO have developed since its discovery by Wu and his co-workers, such as ] (CVD),<ref name="hous" /><ref name=earnshaw /> ],<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 ]<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 (]), a source of fluorine, prevents the formation of the undesired ] (BaCO<sub>3</sub>). Routes such as CSD (chemical solution deposition) have opened a wide range of possibilities, particularly in the preparation of long length YBCO tapes.<ref>{{cite journal|author = O. Castano, A. Cavallaro, A. Palau, J. C. Gonzalez, M. Rossell, T. Puig, F. Sandiumenge, N. Mestres, S. Pinol, A. Pomar, and X. Obradors|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 }}</ref> This route lowers the temperature necessary to get the correct phase to around 700 °C. This, and the lack of dependence on vacuum, makes this method a very promising way to get scalable YBCO tapes. However, new possibilities have been opened since the discovery that trifluoroacetic acid (]), a source of fluorine, prevents the formation of the undesired ] (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== ==Structure==
] ]
YBCO crystallises in a defect ] consisting of layers. The boundary of each layer is defined by planes of square planar CuO<sub>4</sub> units sharing 4 vertices. The planes can some times be slightly puckered.<ref name="hous" /> Perpendicular to these CuO<sub>2</sub> planes are CuO<sub>4</sub> ribbons sharing 2 vertices. The ] atoms are found between the CuO<sub>2</sub> planes, while the ] atoms are found between the CuO<sub>4</sub> ribbons and the CuO<sub>2</sub> planes. This structural feature is illustrated in the figure to the right. YBCO crystallizes in a defect ] consisting of layers. 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 ] atoms are found between the CuO<sub>4</sub> planes, while the ] 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;"
===More details===
|+ ] 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 = ] | volume = 37 | year = 1988 | issue = 13 | pages = 7960–7962 | doi = 10.1103/PhysRevB.37.7960 | pmid = 9944122 }}</ref><ref name="earnshaw" />
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 less than seven oxygen atoms per formula unit are ]s. The structure of these materials depends on the oxygen content. This non-stoichiometry is denoted by the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-''x''</sub> in the chemical formula. When ''x'' = 1, the O(1) sites in the Cu(1) layer 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. Optimum superconducting properties occur when ''x'' ~ 0.07, i.e., almost all of the O(1) sites are occupied, with few vacancies.
|]||]||]||]||]
|-
|cubic {YO<sub>8</sub>}||{BaO<sub>10</sub>}||] {CuO<sub>4</sub>}||] {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;"
In experiments where other elements are substituted at the Cu and Ba 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|pages=200|doi=10.1016/S0921-4534(98)00130-0|title=Crystal growth of superconductive PrBa2Cu3O7−y|last1=Oka|first1=K}}</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 ]s in the same general class, the anisotropy is even greater and inter-plane transport is highly restricted.
|+
|]||]
|-
|puckered Cu plane||Cu ribbons
|}


]s, YBCO can exhibit ]: 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" />]]
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.
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 ]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 ]) are vacant and the structure is ]. 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 ], 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 (] 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 ]s in the same general class, the anisotropy is even greater and inter-plane transport is highly restricted.
==Superconductive properties==
It is a ].


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.
] : 120&nbsp;nm in the ''ab'' plane, 800&nbsp;nm along the ''c'' axis.{{Citation needed|date=June 2009}}<!-- disputed on talk page-->

] : 2&nbsp;nm in the ''ab'' plane, 0.4&nbsp;nm along the ''c'' axis.

===Properties of single crystals===
The ] is 120 ] for ] perpendicular and 250 T for '''B''' parallel to the CuO<sub>2</sub> planes.

===Bulk properties===
Bulk properties depend greatly on the manner of synthesis and treatment because of the effect on crystal size, alignment, and density and type of lattice defects.

==Applications in technology==
"The implementation of thin-film YBCO receiver coils has improved the signal-to-noise ratio of nuclear magnetic resonance (NMR) spectrometers by a factor of 3 compared to that achievable with conventional coils."<ref></ref>


==Proposed applications==
Several commercial applications of high temperature superconducting materials have been realized. For example, superconducting materials are finding use as ] in ], ], and ]s. (The most used material for power cables and magnets is ].)
]
Many possible applications of this and related high temperature superconducting materials have been discussed. For example, superconducting materials are finding use as ] in ], ], and ]s. (The most used material for power cables and magnets is ].){{Citation needed|date=October 2021}}


YBCO has yet to be used in many applications involving superconductors for two primary reasons: YBCO has yet to be used in many applications involving superconductors for two primary reasons:
*First, while single crystals of YBCO have a very high ], ]s have a very low critical ]: only a small current can be passed while maintaining superconductivity. This problem is due to crystal ] 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 CVD or by texturing the material to align the grain boundaries. *First, although single crystals of YBCO have a very high critical current density, ]s have a very low critical ]: only a small current can be passed while maintaining superconductivity. This problem is due to crystal ] 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 ] 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 wires by any conventional process does not produce a useful superconductor. (Unlike ], the ] process does not give good results with YBCO.) *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 ]s by any conventional process does not produce a useful superconductor. (Unlike ], the ] 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 ] 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 ], Superpower (a division of ]), ], ], ] Superconductors, ], 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 may be the key to a ] fusion reactor design that can achieve ] energy production.<ref>. Newsoffice.mit.edu. Retrieved on 2015-12-09.</ref> YBCO is often categorized as a ] (REBCO).<ref></ref>
It should be noted that cooling materials to ] temperature (77 K) is often not practical on a large scale, although many commercial magnets are routinely cooled to liquid helium temperatures (4.2 K).


==Surface modification==
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 '''coated conductor'''. Texture (crystal plane alignment) can be introduced into the metal tape itself (the ] process) or a textured ceramic buffer layer can be deposited, with the aid of an ion beam, on an untextured alloy substrate (the ] 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 ], Superpower (a division of Intermagnetics General Corp), ], Fujikura, Nexans Superconductors, and European Advanced Superconductors. A much larger number of research institutes have also produced YBCO tape by these methods.
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 ]. Thus far, YBCO layered with alkylamines, arylamines, and ]s have been produced with varying stability of the molecular layer. It has been proposed that amines act as ] and bind to ] Cu surface sites in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> to form stable ]s.
==Surface modification of YBCO==
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 YBa2Cu3O7-δ|author=F. Xu ''et al.''|page=6505|doi=10.1021/la980143n}}</ref>


==Mass production==
These molecular layered materials are synthesized using ]. Thus far, YBCO layered with alkylamines, arylamines, and thiols have been produced with varying stability of the molecular layer. It has been proposed that amines act as Lewis bases and bind to Lewis acidic Cu surface sites in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> to form stable coordination bonds.
]
In 1987, shortly after it was discovered, physicist and science author ] published in the U.K. Journal '']'' 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>
==Media==
] (however, this effect is NOT being demonstrated here). Below its critical temperature, YBCO becomes perfectly ] and excludes sufficiently weak magnetic fields from passing through it.<ref name="hous" />]]


==References== ==References==
{{reflist|2}} {{reflist|30em}}


==External links== ==External links==
{{Commons category}}
* *
*{{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}}
* - ]
* *
*. *.
*. * {{Webarchive|url=https://web.archive.org/web/20051205121000/http://www.superlife.info/ |date=2005-12-05 }}.

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


{{DEFAULTSORT:Yttrium Barium Copper Oxide}} {{DEFAULTSORT:Yttrium Barium Copper Oxide}}
Line 118: Line 141:
] ]
] ]
]
] ]
] ]
Line 125: Line 147:
] ]
] ]

]
]
]
]
]
]
]
]
]