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Free keywords:
sensor; space charge; simulation; oxygen incorporation; mixed conductor
Abstract:
The change of resistance of SnO2 upon the change of oxygen
partial pressure-a well known sensor effect-is studied
theoretically. A linearised drift-diffusion model is used. The
boundary conditions are formulated in terms of reaction rate
equations. Resistance vs. time curves as well as the evolution
of the concentration profiles of electrons and oxygen vacancies
are numerically calculated anti discussed. Analytical
approximations are derived for the corresponding time
constants. Relevance of the model for commercial sensors is
discussed. (C) 2002 Elsevier Science B.V. All rights reserved.