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Diffusion in Materials with Ionic and Electronic Disorder
Published online by Cambridge University Press: 28 February 2011
Abstract
Besides some necessary reviewing of conventional diffusion theory, this paper deals with the modification of the mass and charge transport equations originating from the occurence of internal defect-chemical reactions (especially valence changes of the defects) which can be considered to be in local equilibrium. It is shown how the phenomenological transport coefficients for chemical diffusion, tracer diffusion and ionic conduction depend on the individual defect diffusivities under such general conditions. Moreover, the evaluation formulae of well-known electrochemical techniques such as Wagner-Hebb polarization and concentration cell experiments have to be modified. Application is made to the influence of trapping effects in doped SrTi03, to the valence changes in YBa2Cu3O6+x as well as to the mixed conduction in orthorhombic PbO.
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- Copyright © Materials Research Society 1991
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