YTTRIUM BARIUM COPPER OXIDE

Definition Yttrium barium copper oxide YBCO, is a family

of crystalline chemical compounds, famous for displaying "high-temperature superconductivity". Many YBCO compounds have the general formula YBa2Cu3O7-x (also known as Y123), although materials with other Y:Ba:Cu ratios exist, such as YBa2Cu4Oy (Y124) or Y2Ba4Cu7Oy (Y247).

Lattice structure

Description

• The boundary of each layer is defined by planes of square planar CuO4 units sharing 4 vertices.•The yttrium atoms are found between the CuO2 planes.•The barium atoms are found between the CuO4 ribbons and the CuO2 planes.

Note - The structure of these materials depends on the oxygen content. YBa2Cu3O7-x x = 1 tetragonal no super conduction 0 ≤ x ≤ 0.65 orthorhombic superconducting

What is Superconductivity?

Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.

Like ferromagnetism, superconductivity is a quantum mechanical phenomenon.

It is characterized by the Meissner effect. The complete ejection of magnetic field lines from the

interior of the superconductor as it transitions into the superconducting state.

VIDEO MAY NOT PLAY HERE so link is providedhttps://www.youtube.com/watch?v=s5f17VLp9Co

PropertiesIUPAC name Barium Copper Yttrium Oxide

Chemical formula YBa2Cu3O7

Molecular mass 666.19 g/mol

Appearance Black solid

Density 6.3 g/cm

Melting point >1000 °C

Solubility in water Insoluble

Synthesis

Pure YBCO was synthesized by heating a mixture of the metal carbonates at temperatures between 1000 to 1300 K.

4 BaCO3 + Y2(CO3)3 + 6 CuCO3 + (1/2−x) O2 → 2 YBa2Cu3O7−x + 13 CO2

The superconducting properties of YBa2Cu3O7−x are sensitive to the value of x, its oxygen content.

Only those materials with 0 ≤ x ≤ 0.65 are superconducting below Tc.

When x ~ 0.07 the material superconducts at the highest temperature of 95 K.

The properties of YBCO are influenced by the crystallization methods used.

Care must be taken to sinter YBCO. YBCO is a crystalline material, and the best

superconductive properties are obtained when crystal grain boundaries are aligned by careful control of annealing and quenching temperature rates.

Other methods

1. Chemical vapour deposition (CVD)2. Sol-gel method3. Aerosol method

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/high-Tc superconductor trilayer structures, and the fabrication of superconductor tunnel junctions have been developed using surface-modified YBCO.

These molecular layered materials are synthesized using cyclic voltammetry.

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.

Applications

Used as magnets in magnetic resonance imaging

Magnetic levitation

Josephson junctions

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

References

1. http://es.slideshare.net/laubesapei/yttrium-barium-copper-oxide

2. https://www.youtube.com/watch?v=0IkiEQTpqgU3. https://en.wikipedia.org/wiki/Yttrium_barium_co

pper_oxide4. http://www.nature.com/nature/journal/v421/

n6922/full/nature01350.html

Facts about Superconductor

1. Before Onnes created liquid helium, the lowest temperature available to researchers was 14 K from solid hydrogen.

2. Five Nobel Prizes in Physics have been awarded for research in superconductivity.

3. Transport vehicles such as trains can be made to "float" on strong superconducting magnets, virtually eliminating friction between the train and its tracks.