Defect chemistry of the high-Tc superconductors

Authors

  • Prof. Joachim Maier,

    1. Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, W-7000 Stuttgart 80 (FRG)
    Search for more papers by this author
    • Studied chemistry at the University of the Saarland, FRG and gained his Ph.D. in the field of physical chemistry (with G. Schwitzgebel) before joining the solid state chemistry group of A. Rabenau at the Max Planck Institute for Solid State Research in Stuttgart. He habilitated at the University of Tübingen (with W. Göpel) before moving to the Max Planck Institute for Metals Research in 1988. In 1989 he was a visiting professor in materials science at the Massachusetts Institute of Technology, Cambridge, U.S.A., and is a faculty member there (as a foreign Associate Professor). Prof. Maier has received several awards and nominations, for example, the Young Author's award of the Electrochemical Society, the Chemistry Dozent Scholarship of the Fonds der Chemischen Industrie and the Carl-Duisberg Award of the GdCh. From July 1991 on, he will be a scientific member of the Max Planck society and a Director at the Max Planck Institute for Solid State Research in Stuttgart. His main area of interest is the thermodynamics and kinetics of the solid state, particularly with respect to electrical properties.

  • Gösta Pfundtner

    1. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, W-7000 Stuttgart 80 (FRG)
    Search for more papers by this author

Abstract

In the high temperature superconductors the critical temperature is intimately connected to the electronic charge-carrier concentration. The absolute values of this quantity and its dependencies on the controlling parameters temperature, oxygen partial pressure and doping content, is phenomenologically determined by the thermodynamics and kinetics of reactions involving point defects. Due to the low mobility of the ionic constituents the behavior at elevated temperatures is particularly important. Here, the kinetics are controlled by the mass transport parameters, essentially by the ionic conductivity.

The scientific discipline whose objective is precisely described in the above terms is called defect chemistry. It quantitatively deals with the nature of excess and lacking native ionic or electronic particles as well as with foreign species. It describes the thermodynamics and kinetics of their formation, annihilation, interaction and motion in the phase under consideration and thus determines the chemistry within this phase.

Ancillary