Interfacial effects in potentiometric oxygen sensors: The role of transport properties and thickness of solid electrolyte ceramics
authors Frade, JR; Kharton, VV; Shaula, AL; Marques, FMB
nationality International
journal SENSOR LETTERS
author keywords potentiometric oxygen sensor; solid electrolyte; e.m.f. measurements; electrode polarization; transport number; sensor accuracy; electrolyte thickness
keywords OXIDE FUEL-CELLS; NONFLOWING ATMOSPHERES; SURFACE EXCHANGE; EMF-MEASUREMENTS; FUGACITY CONTROL; DOPED CERIA; CONDUCTION; KINETICS; MICROSTRUCTURE; RESISTANCE
abstract Electrode polarization in potentiometric oxygen sensors may lead to significant errors in the oxygen activity measurements, due to minor electronic conduction in solid electrolytes. These errors increase with increasing electronic contribution to total conductivity and electrode polarization resistance, and with decreasing electrolyte thickness. Similar effects have been observed when using oxygen concentration cells for the determination of ion transference numbers of solid electrolytes and mixed conductors. In this work a revised equivalent circuit was used to analyze the e.m.f. reading of potentiometric oxygen sensors under the conditions when electrode polarization cannot be neglected. It is shown that the cell response can be approximately described as E approximate to E(0)t(1)[1 + (L-c/L)], where E-0 is the Nernst potential, t(1) is the ionic transport number, L is the electrolyte thickness, and L, is a critical electrolyte thickness determined by the transport properties of the cell material and interfacial resistance of the electrodes. The errors associated with electrode polarization may be nearly corrected by using impedance spectroscopy to estimate the polarization resistance, and combining these data with the concentration cell e.m.f. However, severe current density limitations are expected for very diluted atmospheres, i.e., under moderately reducing atmospheres; this gives very inaccurate sensor response, and no corrections have been found for this type of deviations.
publisher AMER SCIENTIFIC PUBLISHERS
issn 1546-198X
year published 2008
volume 6
issue 3
beginning page 370
ending page 380
digital object identifier (doi) 10.1166/sl.2008.055
web of science category Chemistry, Analytical; Electrochemistry; Instruments & Instrumentation; Physics, Applied
subject category Chemistry; Electrochemistry; Instruments & Instrumentation; Physics
unique article identifier WOS:000257793100003
  ciceco authors
  impact metrics
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg