Lanthanum cuprate

Lanthanum cuprate
Identifiers
3D model (JSmol)
  • InChI=1S/Cu.2La.4O/q+2;2*+3;4*-2
    Key: VTQXYJGFVOFCDC-UHFFFAOYSA-N
  • [O-2].[O-2].[O-2].[O-2].[Cu+2].[La+3].[La+3]
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).

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 °C (30.1 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. ^ a b Longo, J.M.; Raccah, P.M. (1973). "The structure of La2CuO4 and LaSrVO4". Journal of Solid State Chemistry. 6 (4): 526–531. Bibcode:1973JSSCh...6..526L. doi:10.1016/S0022-4596(73)80010-6.
  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. Bibcode:1986ZPhyB..64..189B. doi:10.1007/BF01303701. S2CID 118314311.