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Conductivity Relaxation Studies On La0.5Sr0.5Co0.8Ga0.2O3−δ

Published online by Cambridge University Press:  10 February 2011

S. Wang ,
B. Abeles  and
A.J. Jacobson
S. Wang
Affiliation:
Department of Chemistry, University of Houston, Houston, TX 77204-5641
B. Abeles
Affiliation:
Department of Chemistry, University of Houston, Houston, TX 77204-5641
A.J. Jacobson
Affiliation:
Department of Chemistry, University of Houston, Houston, TX 77204-5641
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Abstract

The surface exchange coefficient, ki, of the mixed ionic electronic conductor perovskite, La0.5Sr0.5Co0.8Ga0.2O3−δ, was determined in the temperature range 600-900°C by electrical conductivity relaxation on thin plate and long bar samples, using four probe dc conductivity measurements. The normalized conductivity could be fitted by the equation corresponding to surface limited relaxation, (σ(t) − σ1) / (σ2 − σ1) = 1 − exp(−t / Tr), where τ = l1l2 / [(l1 + l2)Γki], σ(t), σ1 and σ2 are the time dependent, initial and final conductivities, Γ is the thermodynamic factor and 21, and 212 are the lateral sides of the bar. Numerical simulation shows that the shape of the relaxation curve for the plate geometry changes only little in going from surface limited to diffusion limited transport, the change is significantly larger for the bar geometry.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 548: Symposia EE – Solid State Ionics V , 1998 , 557
Copyright
Copyright © Materials Research Society 1999

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References

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