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Internal Precipitation of Molecular Oxygen and Electromechanical Failure of Zirconia Solid Electrolytes
Author(s) -
Virkar Anil V.,
Nachlas Jesse,
Joshi Ashok V.,
Diamond Jordan
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb06465.x
Subject(s) - electrolyte , materials science , fast ion conductor , ionic conductivity , cubic zirconia , oxygen , conductivity , electrochemistry , inorganic chemistry , electrode , chemical engineering , ceramic , composite material , chemistry , organic chemistry , engineering
The phenomenon of electromechanical failure of zirconia has been examined. It is shown that spatial variation of electronic conductivity in a predominantly oxygen ion conductor can lead to internal precipitation of molecular oxygen and its pressurization. Internal pressures high enough to crack zirconia can develop if the electronic conductivity is higher on the oxygen exit side. The calculations demonstrate that the kinetics of pressurization are very sensitive to the relative magnitudes of the electronic and the ionic conductivities. Oxygen was electrolyzed at 800°C through zirconia solid electrolytes with lanthanum strontium manganate (LSM) electrodes under an applied dc potential of 1.0 V. Spalling of the solid electrolytes was observed. Composite disk electrolytes were fabricated such that part of the disk contained TiO 2 as a dopant which was added to enhance the electronic conductivity. The electrolytes exhibited severe cracking and pitting when the TiO 2 ‐doped region was on the oxygen exit side. No degradation occurred when the TiO 2 ‐doped region was on the oxygen entry side. Implications regarding the use of mixed conductors as dense electrodes in electrochemical systems are discussed.