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Yttrium barium copper oxide, often abbreviated YBCO, is a chemical compound with the formula YBa2Cu3O7. This material, a famous "high-temperature superconductor", achieved prominence because it was the first material to superconduct above the boiling point of nitrogen. Image File history File links BaYCusuperconduct. ...
IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ...
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In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: Ï (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is...
In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ...
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The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ...
The coordination geometry of an atom is the geometrical pattern formed by its neighbors in a molecule or a crystal. ...
In crystallography, the tetragonal crystal system is one of the 7 lattice point groups. ...
Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ...
Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. ...
Council Directive 67/548/EEC of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (as amended) is the main European Union law concerning chemical safety. ...
NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ...
Unsolved problems in physics: Why do certain materials exhibit superconductivity at temperatures much higher than 50 kelvins? The term high-temperature superconductor was initially employed to designate the new family of cuprate-perovskite ceramic materials discovered by J.G. Bednorz and K.A. Müller in 1986. ...
Yttrium oxide is Y2O3. ...
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Copper(II) oxide or cupric oxide (CuO) is the higher oxide of copper. ...
In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ...
A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ...
General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Atomic mass 88. ...
For other uses, see Barium (disambiguation). ...
For other uses, see Copper (disambiguation). ...
General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...
Unsolved problems in physics: Why do certain materials exhibit superconductivity at temperatures much higher than 50 kelvins? The term high-temperature superconductor was initially employed to designate the new family of cuprate-perovskite ceramic materials discovered by J.G. Bednorz and K.A. Müller in 1986. ...
General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...
History
Seventy-five years after the discovery of superconductivity, Georg Bednorz and Alexander Müller, working at IBM in Zurich Switzerland, discovered that certain semiconducting oxides became superconducting at the then relatively high temperature of 35 K. In particular, the lanthanum barium copper oxides, an oxygen deficient perovskite-related material proved particularly promising. Johannes Georg Bednorz (born May 16, 1950) is a German physicist who, along with Karl Alex Muller, was awarded the 1987 Nobel Prize for Physics for their joint discovery of superconductivity in certain substances at temperatures higher than had previously been thought attainable. ...
Karl Alexander Müller (born April 20, 1927) is a Swiss physicist who, along with J. Georg Bednorz, was awarded the 1987 Nobel Prize for Physics for their joint discovery of superconductivity in certain substances at higher temperatures than had previously been thought attainable. ...
Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. ...
Building on the motif discovered by Bednorz and Müller, Maw-Kuen Wu and his graduate students, Ashburn and Torng[citation needed] at the University of Alabama in Huntsville in 1987 and Paul Chu and his students at the University of Houston in 1987 (see superconductor page for info), discovered YBCO. Their work led to a rapid succession of new high temperature superconducting materials, ushering in a new era in material science and chemistry. The University of Alabama (also known as Alabama, UA or colloquially as Bama) is a public coeducational university located in Tuscaloosa, Alabama, USA. Founded in 1831, UA is the flagship campus of the University of Alabama System. ...
Year 1987 (MCMLXXXVII) was a common year starting on Thursday (link displays 1987 Gregorian calendar). ...
The University of Houston, formerly University of Houston–University Park, is a comprehensive doctoral degree-granting university[2] located in Houston, Texas. ...
Superconductivity is a phenomenon occurring in certain materials at low temperatures, characterised by the complete absence of electrical resistance and the damping of the interior magnetic field (the Meissner effect. ...
YBCO was the first material to become superconducting above 77 K, the boiling point of nitrogen. All materials developed before YBCO became superconducting only at temperatures near the boiling points of liquid helium or liquid hydrogen (Tb = 20.1 K). The significance of the discovery of YBCO is the breakthrough in the refrigerant used to cool the material to below the critical temperature. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...
Helium exists in liquid form only at very low temperatures. ...
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Synthesis YBCO was first synthesized by heating a mixture of the metal carbonates at temperatures between 1000 to 1300 K.[2][3] - 4BaCO3 + Y2(CO3)3 + 6 CuCO3 → 2 YBa2Cu3O{7-x} + 13 CO2 + (3+x)O2
Modern syntheses of YBCO use the corresponding oxides and nitrates.[3]
The superconducting property of YBa2Cu3O{7-x} is sensitive to the value of x, its oxygen content. Only those materials with 0 ≤ x ≤ 0.5 are superconducting below Tc, and when x ~ 0 the material superconducts at the highest temperature, 95 K.[3]
In addition to being sensitive to the stoichiometry of oxygen, the properties of YBCO are influenced by the crystallization methods. Care must be taken to sinter YBCO. YBCO is a crystalline material, and the best superconduction performance is obtained when crystal grain boundaries are aligned by careful control of annealing and quenching temperature rates. Sintering is a method for making objects from powder, increasing the adhesion between particles as they are heated. ...
Anneal may refer to: Annealing (metallurgy), a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. ...
Quenching is a general term for non-radiative de-excitation. ...
Numerous other methods to synthesize YBCO have developed since its discovery by Wu and his coworkers, such as chemical vapor deposition (CVD)[2][3], sol-gel[4], and aerosol[5] methods. These alternative methods, however, still require careful sintering to produce a quality product. DC plasma (violet) enhances the growth of carbon nanotubes in this laboratory-scale PECVD apparatus. ...
Sol gel is a colloidal suspension of silicon dioxide that is gelled to form a solid. ...
Aerosol, is a term derived from the fact that matter floating in air is a suspension (a mixture in which solid or liquid or combined solid-liquid particles are suspended in a fluid). ...
Structure YBCO crystallises in a defect perovskite structure consisting of layers. The boundary of each layer is defined by planes of square planar CuO4 units sharing 4 vertices. The planes can some times be slightly puckered[2]. Perpendicular to these CuO2 planes are CuO4 ribbons sharing 2 vertices. The yttrium atoms are found between the CuO2 planes, while the barium atoms are found between the CuO4 ribbons and the CuO2 planes. This structural feature is illustrated in the figure below. Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. ...
General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Atomic mass 88. ...
For other uses, see Barium (disambiguation). ...
 Image File history File linksMetadata Size of this preview: 701 × 599 pixelsFull resolution (800 × 684 pixel, file size: 104 KB, MIME type: image/jpeg) This image is corrected from that shown in ybco003. ...
More details Although YBa2Cu3O7 is a well defined chemical compound with a specific structure and stoichiometry, materials with less than seven oxygen atoms per formula unit are non-stoichiometric compounds. The structure of these materials depends on the oxygen content. This nonstoichiometry is denoted by the ( δ) in the chemical formula. With δ = 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 δ < 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 δ ~0.07 and all of the O(1) sites are occupied with few vacancies. Non-stoichiometric compounds are chemical compounds with an elemental composition that cannot be represented by a ratio of well-defined natural numbers, and are therefore in violation of the law of definite proportions. ...
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. (cite needed!) However, this model fails to address superconductivity in the homologue Pr123 (Praseodymium instead of Yttrium)[6].
Furthermore the superconducting length scales show similar anisotropy, the penetration depth ( ,  ) and the coherence length, ( ,  ). 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. ( ). 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.
Applications in technology Several commercial applications of high temperature superconducting materials have been realized. For example, superconducting materials are finding use as magnets in magnetic resonance imaging, magnetic levitation, and Josephson junctions. “MRI†redirects here. ...
Levitating pyrolytic carbon Magnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended above another object with no support other than magnetic fields. ...
Josephson junctions, first postulated by B. D. Josephson and first made by John Rowell and Philip Anderson, are quantum-mechanical circuit elements of superconducting devices. ...
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 critical current density, polycrystals have a very low critical current density i.e., 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 degrees 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.
- A second problem limiting using 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.
Finally, it should be noted that cooling materials to liquid nitrogen temperature is often not practical on a large scale, although many commercial magnets are routinely cooled to liquid helium temperatures. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...
The most promising method developed to utilize this material involves deposition of YBCO on flexible metal tapes coated with buffering metal oxides. Texture can be introduced into the metal tape itself (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 Intermagnetics General Corp), Sumitomo, Fujikura, Nexans Superconductors, and European Advanced Superconductors. A much larger number of research institutes have also produced YBCO tape by these methods. Ion beam assisted deposition or IBAD (not to be confused with ion beam induced deposition, IBID) is a materials engineering technique which combines ion implantation with simultaneous sputtering or another physical vapor deposition technique. ...
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-Tc superconductor trilayer structures, and the fabrication of metal/insulator/ superconductor tunnel junctions have been developed using surface modified YBCO[7].
These molecular layered materials are synthesized using cyclic voltammetry. 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 YBa2Cu3O7 to form stable coordination bonds. Typical cyclic voltammogram Cyclic voltammetry is a type of potentiodynamic electrochemical measurement. ...
Magnetic levitation Similar to all superconductors, YBCO displays the Meissner effect as it is cooled and reaches its critical temperature. At the critical temperature and below, YBCO becomes perfectly diamagnetic and excludes all magnetic fields from passing through it by developing an internal magnetic field that perfectly balances the externally applied magnetic field. This internal field causes any magnet on the surface of the superconductor to levitate[2]. See full article Meissner Effect Diagram of the Meissner effect. ...
Diamagnetism is a very weak form of magnetism that is only exhibited in the presence of an external magnetic field. ...
Diagram of the Meissner effect. ...
Media Image File history File links Flyingsuperconductor. ...
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References - ^ R. Swarup, A. K. Gupta and M. C. Bansal (1995). "Effect of sample density on magnetic penetration depth in YBaCuO ceramic superconductors". Journal of Superconductivity 8 (3): 361-364. DOI:10.1007/BF00728172.
- ^ a b c d C. E. Housecroft, A. G. Sharpe and C. E. Housecroft (2005). Inorganic chemistry. Pearson Prentice Hall. ISBN 0130399132.
- ^ a b c d N. N. Greenwood and A. Earnshaw (1997). Chemistry of the elements. Butterworth-Heinemann. ISBN 0750633654 (pbk.).
- ^ Yang-Kook Sun, In-Hwan Oh Ind. Eng. Chem. Res. 1996, 35, 4296
- ^ Zhou, Derong (1991). Yttrium Barium Copper Oxide Superconducting Powder Generation by An Aerosol Process (Ph.D. Thesis). University of Cincinnati.
- ^ Oka, et al. Physica C, v 300, n 3-4, 10 May 1998, 200-6
- ^ Xu et al. Langmuir, 1998, 14 (22)
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