Chemistry:Lanthanum cuprate

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Lanthanum cuprate
Sr 2 Ru O 4 Layered Perovskite Structure.svg
Identifiers
3D model (JSmol)
Properties
CuLa2O4
Molar mass 405.353 g·mol−1
Appearance solid
Density 7.05 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Lanthanum cuprate usually refers to the inorganic compound with the formula CuLa2O4. The name implies that the compound consists of a cuprate (CuOn]2n-) salt of lanthanum (La3+). In fact it is a highly covalent solid. It is prepared by high temperature reaction of lanthanum oxide and copper(II) oxide follow by annealing under oxygen.[1]

The material adopts a tetragonal structure related to potassium tetrafluoronickelate (K2NiF4), which is orthorhombic.[1][2] Replacement of some lanthanum by barium gives the quaternary phase CuLa1.85Ba0.15O4, called lanthanum barium copper oxide. That doped material displays superconductivity at −243 K, which at the time of its discovery was a high temperature. This discovery initiated research on cuprate superconductors and was the basis of a Nobel Prize in Physics to Georg Bednorz and K. Alex Müller.[3]

References

  1. 1.0 1.1 Longo, J.M.; Raccah, P.M. (1973). "The structure of La2CuO4 and LaSrVO4". Journal of Solid State Chemistry 6 (4): 526–531. doi:10.1016/S0022-4596(73)80010-6. Bibcode1973JSSCh...6..526L. 
  2. Grande, B.; Müller-Buschbaum, Hk.; Schweizer, M. (1977). "Über Oxocuprate. XV zur Kristallstruktur von Seltenerdmetalloxocupraten: La2CuO4, Gd2CuO4". Zeitschrift für Anorganische und Allgemeine Chemie 428: 120–124. doi:10.1002/zaac.19774280116. 
  3. Bednorz, J. G.; Müller, K. A. (1986). "Possible High Tc Superconductivity in the Ba-La-Cu-O System". Zeitschrift für Physik B: Condensed Matter 64 (2): 189–193. doi:10.1007/BF01303701. Bibcode1986ZPhyB..64..189B.