Layered Lead Cuprates: Promising high- Tc superconductors

Authors

  • Prof. B. Raveau,

    1. Laboratoire de Cristallographie et Sciences des Matériaux, ISMRa, Bd du Maréchal Juin, F-14032 Caen Cedex (France)
    Search for more papers by this author
    • graduated as a chemical engineer in 1962 and followed this with a Ph.D. in physics in 1966 from the University of Caen. He then embarked on an academic career becoming a professor in 1970 and a full profesor in 1978 both at Caen University and at the Institute des Sciences de la Matière et du Rayonnement (ISM Ra). His principle research interests include the study of non-stoichiometry in oxides and new ceramic materials. He ha authored 10 patents and over 420 research papers and has been awarded several prizes for his work, including the Prix Osiris de l'Académie des Sciences (1987), and Médaille d'Argent du CNRS (1988).

  • Dr. C. Michel,

    1. Laboratoire de Cristallographie et Sciences des Matériaux, ISMRa, Bd du Maréchal Juin, F-14032 Caen Cedex (France)
    Search for more papers by this author
  • Dr. M. Hervieu,

    1. Laboratoire de Cristallographie et Sciences des Matériaux, ISMRa, Bd du Maréchal Juin, F-14032 Caen Cedex (France)
    Search for more papers by this author
  • Dr. D. Groult,

    1. Laboratoire de Cristallographie et Sciences des Matériaux, ISMRa, Bd du Maréchal Juin, F-14032 Caen Cedex (France)
    Search for more papers by this author
  • Dr. J. Provost

    1. Laboratoire de Cristallographie et Sciences des Matériaux, ISMRa, Bd du Maréchal Juin, F-14032 Caen Cedex (France)
    Search for more papers by this author

Abstract

Layered lead cuprates belong to the structural family [ACuO3−α]m (A′O)n which are characterized by the intergrowth of oxygen deficient perovskite layers and rock salt type layers. Located in the rock salt type layers, lead sometimes exhibits the divalent state and sometimes the tetravalent state. A feature of some of these oxides is the disproportionation of Cu(II) to Cu(III) and Cu(I), which up to now has only been observed in YBa2Cu3O7−δ. The superconducting properties of these phases are very promising with the Tc ranging from 40 to 100 K, but the materials also show broad resistive transitions due to oxygen inhomogeneity. The dramatic influence of the method of synthesis on these properties is studied. The issue of the incommensurability of several of these structures is discussed.

Ancillary