TRANSPORT ACROSS BOUNDARY-LAYERS IN IONIC-CRYSTALS PART II - STATIONARY CHEMICAL DIFFUSION

Authors
Citation
J. Jamnik et J. Maier, TRANSPORT ACROSS BOUNDARY-LAYERS IN IONIC-CRYSTALS PART II - STATIONARY CHEMICAL DIFFUSION, Journal of physics and chemistry of solids, 59(9), 1998, pp. 1555-1569
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics, Condensed Matter",Chemistry
ISSN journal
0022-3697
Volume
59
Issue
9
Year of publication
1998
Pages
1555 - 1569
Database
ISI
SICI code
0022-3697(1998)59:9<1555:TABIIP>2.0.ZU;2-N
Abstract
Defect concentration and charge density profiles are derived for a mix ed conductor MO1+delta with two carriers under a small chemical potent ial gradient. The description starts from the formulation of the flux equations for the diffusing species of relevance (e.g. O2- and 2e(-) i n an oxide), takes account of the Poisson equation and is restricted t o dilute systems and linear regime. Several examples are discussed in detail: (i) it is shown analytically that chemical diffusion involving carriers with different diffusion coefficients leads to a kinetic bui ld-up of subsurface space charges; (ii) the influence of sluggish surf ace reactions on the steady state flux and the concentrations profiles is studied on both a ''black box'' and a mechanistic level; (iii) the impact of different prototype grain boundaries (amorphous blocking co re, depletion of carriers in adjacent space charge layers) on chemical diffusion is treated in detail numerically. (C) 1998 Elsevier Science Ltd. All rights reserved.