Electrical Conductivity Relaxation Study of Solid Oxide Fuel Cell Cathodes using Epitaxial (001)-Oriented Strontium-Doped Lanthanum Manganite Thin Films

2010 ◽  
Vol 1255 ◽  
Author(s):  
Lu Yan ◽  
Balasubramaniam Kavaipatti ◽  
Shanling Wang ◽  
Hui Du ◽  
Paul Salvador
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Elevated Temperatures ◽  
Reduction Process ◽  
Lanthanum Manganite ◽  
Conductivity Relaxation ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Crystal Films ◽  
Surface Exchange Coefficient

AbstractEpitaxial single-crystal films of La0.7Sr0.3MnO3 (100) having smooth surface morphology were deposited on SrTiO3 (100) substrates by pulsed laser deposition (PLD). Electrical conductivity relaxation (ECR) measurements were carried out at elevated temperatures over a range of absolute oxygen pressures to determine the oxygen surface exchange coefficient. Steady-state conductivity data of the thin films show good agreement with the bulk material's properties. The values of the oxygen exchange coefficients (Kchem) are found to be similar for both oxidation and reduction process between 50 and 500 mTorr O2. The activation energy (Ea) of Kchem is 1.00±0.27 eV at temperatures above 600 °C and Kchem (T=612°C)≈1.2×10-6 cm/s.

scholarly journals Untangling surface oxygen exchange effects in YBa2Cu3O6+x thin films by electrical conductivity relaxation

2017 ◽  
Vol 19 (21) ◽  
pp. 14129-14140 ◽  
Author(s):  
P. Cayado ◽  
C. F. Sánchez-Valdés ◽  
A. Stangl ◽  
M. Coll ◽  
P. Roura ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Exchange Process ◽  
Bulk Diffusion ◽  
Epitaxial Thin Films ◽  
Conductivity Relaxation ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Relaxation Measurements ◽  
Kinetics Of

The kinetics of oxygen incorporation and excorporation in YBCO epitaxial thin films was investigated by electrical conductivity relaxation measurements showing that the oxygenation kinetics of YBCO films is limited by the surface exchange process of oxygen molecules prior to bulk diffusion into the films.

scholarly journals Influence of Heterointerfaces on the Kinetics of Oxygen Surface Exchange on Epitaxial La1.85Sr0.15CuO4 Thin Films

2021 ◽  
Vol 11 (9) ◽  
pp. 3778
Author(s):  
Gene Yang ◽  
So-Yeun Kim ◽  
Changhee Sohn ◽  
Jong K. Keum ◽  
Dongkyu Lee
Keyword(s):  
Thin Films ◽  
Oxygen Vacancies ◽  
Elevated Temperatures ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Exchange Kinetics ◽  
Relaxation Curves ◽  
Kinetics Of ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Considerable attention has been directed to understanding the influence of heterointerfaces between Ruddlesden–Popper (RP) phases and ABO3 perovskites on the kinetics of oxygen electrocatalysis at elevated temperatures. Here, we report the effect of heterointerfaces on the oxygen surface exchange kinetics by employing heteroepitaxial oxide thin films formed by decorating LaNiO3 (LNO) on La1.85Sr0.15CuO4 (LSCO) thin films. Regardless of LNO decoration, tensile in-plane strain on LSCO films does not change. The oxygen surface exchange coefficients (kchem) of LSCO films extracted from electrical conductivity relaxation curves significantly increase with partial decorations of LNO, whereas full LNO coverage leads to the reduction in the kchem of LSCO films. The activation energy for oxygen exchange in LSCO films significantly decreases with partial LNO decorations in contrast with the full coverage of LNO. Optical spectroscopy reveals the increased oxygen vacancies in the partially covered LSCO films relative to the undecorated LSCO film. We attribute the enhanced oxygen surface exchange kinetics of LSCO to the increased oxygen vacancies by creating the heterointerface between LSCO and LNO.

A Study of the Oxygen Transport Kinetics in SrFeO3-x

2002 ◽  
Vol 756 ◽  
Author(s):  
Jiho Yoo ◽  
Allan J. Jacobson
Keyword(s):  
Electrical Conductivity ◽  
Oxygen Transport ◽  
Diffusion Coefficients ◽  
Abrupt Change ◽  
Vacancy Diffusion ◽  
Conductivity Relaxation ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Oxygen Ion ◽  
Thermodynamic Factors

ABSTRACTExperimental results from electrical conductivity relaxation (ECR) measurements on SrFeO3-x are described. Values of Dchem and kchem were obtained by monitoring the variation of the time dependence of the electrical conductivity after an abrupt change in the oxygen partial pressure. Values for the oxygen ion and vacancy diffusion coefficients were calculated from the measured thermodynamic factors and compared with those of other compositions in the series La1-xSrxFeO3-x. The surface exchange coefficients, kchem and kex were also determined.

scholarly journals Chemical surface exchange of oxygen on CeO2−δ in an O2/H2O atmosphere

2017 ◽  
Vol 19 (43) ◽  
pp. 29287-29293
Author(s):  
Ho-Il Ji ◽  
Xin Xu ◽  
Sossina M. Haile
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Method ◽  
Parallel Process ◽  
Conductivity Relaxation ◽  
Surface Exchange ◽  
Chemical Surface ◽  
Electrical Conductivity Relaxation

As measured by the electrical conductivity relaxation method, oxidation of undoped ceria at 1400 °C under moist oxygen proceeds in a parallel process of uncorrelated oxidation by H2O and by O2.

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

1998 ◽  
Vol 548 ◽  
Author(s):  
S. Wang ◽  
B. Abeles ◽  
A.J. Jacobson
Keyword(s):  
Relaxation Curve ◽  
Conductivity Measurements ◽  
Conductivity Relaxation ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Diffusion Limited ◽  
Mixed Ionic Electronic Conductor ◽  
Surface Exchange Coefficient ◽  
Plate Geometry

ABSTRACTThe 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.

Sign in / Sign up

Export Citation Format

Share Document