Materials in thermodynamic potential gradients
M. Martin
Institute of Physical Chemistry,Aachen University
of Technology, Templergraben 59, D-52056 Aachen, Germany
Abstract: In materials that are exposed to thermodynamic potential
gradients (i.e., gradients of chemical potentials, electrical potential,
temperature, or pressure), transport processes of the mobile components
occur. These transport processes and the coupling between different
processes are not only of fundamental interest, but are also the origin
of degradation processes, such as kinetic demixing and decomposition
and changes in the morphology of the material, all of which are of great
practical relevance.Two classes of materials will be considered: semi-and
ion-conducting oxides and ion-conducting halides. In oxides, kinetic
demixing of the cations in a multicomponent oxide and kinetic decomposition
of the oxide under the influence of an applied thermodynamic potential
gradient will be considered for homovalent oxide solid solutions and
for heterovalently doped oxides. In ion-conducting halides, the morphological
stability of solid/solid interfaces, which are driven by an external
electrical potential gradient, is studied. Monte Carlo simulations show
that the morphological stability of the interface is determined by the
difference in the ionic conductivities of the two crystals.
*Plenary lecture presented at the 17th IUPAC Conference
on Chemical Thermodynamics (ICCT), Rostock, Germany, 28 July - 2 August
2002. Other presentations are published in this issue,
pp.859 -936.
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