Properties of species profiles during oxygen chemical diffusion in oxides

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Abstract

This is a theoretical study of species profiles during the oxygen chemical diffusion in an acceptor doped oxide crystal driven by large changes in the ambient oxygen partial pressure. The oxide crystal containing three species: mobile oxygen vacancy, mobile electron, immobile dopant ion, is considered. Our analysis is based on the expression of the chemical diffusion coefficient obtained in the framework of the concept of conservative ensembles (Maier J., 1993). It is shown that the dependence of chemical diffusion coefficient on ambient oxygen partial pressure in doublelogarithmic coordinates is divided into distinct intervals. For each pressure interval the chemical diffusion equation is reduced to the diffusion equation with a diffusion coefficient which exhibits a power dependence on concentration. First, we analyzed the chemical diffusion under pressure inside each interval. As a result two singularities on the species diffusion profiles can be found: an internal reaction diffusion front, and an ambipolar diffusion front. This ambipolar diffusion front is characterized by a step of the electron concentration, moving inside a specimen. Afterwards, we consider a crystal in which the range of partial pressure spans all considered pressure intervals.

Original languageEnglish
Title of host publicationDiffusion in Materials DIMAT-2017 - 10th International Conference on Diffusion in Materials
EditorsEugen Rabkin, Leonid Klinger, Amy Novick-Cohen, Nachum Frage
PublisherTrans Tech Publications Ltd
Pages153-158
Number of pages6
Volume383
ISBN (Print)9783035711301
DOIs
StatePublished - 1 Jan 2018
Event10th International Conference on Diffusion in Materials, DIMAT 2017 - Haifa, Israel
Duration: 7 May 201712 May 2017

Conference

Conference10th International Conference on Diffusion in Materials, DIMAT 2017
Country/TerritoryIsrael
CityHaifa
Period7/05/1712/05/17

Keywords

  • Acceptor doped oxide
  • Ambipolar chemical diffusion coefficient
  • Ambipolar diffusion front
  • Defects
  • Diffusion
  • Oxides
  • Reaction diffusion front

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