Oxygen surface exchange studies in thin film Gd-doped ceria

2008 ◽  
Vol 92 (24) ◽  
pp. 243109 ◽  
Author(s):  
Annamalai Karthikeyan ◽  
Shriram Ramanathan
Keyword(s):  
Thin Film ◽  
Doped Ceria ◽  
Surface Exchange ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Using Mechano-Electro-Chemical Coupling to Measure the Thin Film Elastic Constants, Thermo-Chemical Expansion Coefficients, and Oxygen Surface Exchange Coefficients of Praseodymium Doped Ceria Presentation Format: Oral Preferred

2018 ◽  
Vol MA2018-01 (32) ◽  
pp. 1942-1942
Author(s):  
Yuxi Ma ◽  
Jason D. Nicholas
Keyword(s):  
Film Stress ◽  
Doped Ceria ◽  
Surface Exchange ◽  
Chemical Expansion ◽  
Young’S Moduli ◽  
Curvature Measurements ◽  
Expansion Coefficients ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

A Multi-beam Optical Stress Sensor (MOSS) is a curvature measurement platform which is commonly used to measure the film stress in bilayer samples. It has been widely used as an in-situ technique to measure the film stress during deposition.1 However, when combined with the dual substrate method proposed by Zhao et al,2 in situ curvature measurements can be used to measure Young’s moduli and thermo-chemical expansion coefficients simultaneously as a function of temperature. Using the curvature relaxation (κR) technique developed recently,3-5 oxygen surface exchange coefficients (kchem) can also be measured as a function of temperature using in situ curvature measurements. In this work, the Young’s moduli, thermo-chemical expansion coefficients and kchem values of praseodymium doped ceria (PCO) were measured as a function of temperature using a MOSS. First, phase pure Pr0.1Ce0.9O1.95 (PCO) powder was prepared through glycine nitrate combustion and subsequent calcination at 1100oC in air. This powder was then pressed in a stainless-steel die and fired to 1450oC to produce a pulsed laser deposition (PLD) target. In preparation for PLD, (001) oriented 9.5% yttria doped zirconia (YSZ) and (001) oriented magnesium oxide (MgO) substrates (Crystec, GmbH) were pre-annealed at 1450oC for 20 hours to remove residual stress within them. PCO PLD was then conducted at 680oC for 20 min, with a 10-2 torr oxygen partial pressure and 350 mJ power density. After deposition, the PCO bilayers were re-equilibrated with air by firing them in air at 1000oC for 1 hour. For dual substrates measurements, stress vs. temperature data for PCO|YSZ and PCO|MgO were collected with a 1oC/min heating rate and a 0.2oC/min cooling rate. The slopes of the stress vs. temperature curves can be expressed by: dσPCO|YSZ/dT = MPCO(αYSZ-αPCO) (1) dσPCO|MgO/dT = MPCO(αMgO-αPCO) (2) where is the stress of bilayer sample, T is the temperature, M is the biaxial modulus of the film, is the thermo-chemical expansion coefficient. With two unknowns and two equations, and were then extracted as a function of temperature. The Young’s moduli were then calculated from assuming a Poisson’s ratio of 0.33 as has been done previously for 6. For κR measurements, relaxation data were recorded at 650~725oC with 25oC increments. The oxygen partial pressure was switched between synthetic air (20%O2-80%Ar) and 10% diluted synthetic air (10% synthetic air-90%Ar). Figure 1 shows the Young’s modulus and thermo-chemical expansion coefficients measured here compared to other literature studies.6-8 In contrast to other studies the present study produced PCO Young’s moduli over a complete range of temperatures. In addition, the PCO Young’s moduli started to decrease significantly once the PCO started to become nonstoichiometric (as indicated by an uptick in chemical expansion in Figure 1b). The PCO kchem values (not shown) were in good agreement with the kchem values measured by other electrode-free techniques, such as optical relaxation.9 Figure 1

scholarly journals Emergence of Rapid Oxygen Surface Exchange Kinetics during in Situ Crystallization of Mixed Conducting Thin Film Oxides

2019 ◽  
Vol 11 (9) ◽  
pp. 9102-9116 ◽  
Author(s):  
Ting Chen ◽  
George F. Harrington ◽  
Juveria Masood ◽  
Kazunari Sasaki ◽  
Nicola H. Perry
Keyword(s):  
Thin Film ◽  
Surface Exchange ◽  
Thin Film Oxides ◽  
In Situ Crystallization ◽  
Exchange Kinetics ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Oxygen surface exchange properties and surface segregation behavior of nanostructured La0.6Sr0.4Co0.2Fe0.8O3−δ thin film cathodes

2019 ◽  
Vol 21 (13) ◽  
pp. 7183-7195 ◽  
Author(s):  
K. Develos-Bagarinao ◽  
J. De Vero ◽  
H. Kishimoto ◽  
T. Ishiyama ◽  
K. Yamaji ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Surface Segregation ◽  
Oxygen Exchange ◽  
Surface Exchange ◽  
Segregation Behavior ◽  
Oxygen Surface Exchange ◽  
Exchange Properties ◽  
Oxygen Surface

Nanostructured LSCF thin films with more enhanced oxygen exchange properties also show a higher tendency to surface segregation.

In situ x-ray studies of oxygen surface exchange behavior in thin film La0.6Sr0.4Co0.2Fe0.8O3−δ

2012 ◽  
Vol 101 (5) ◽  
pp. 051603 ◽  
Author(s):  
B. J. Ingram ◽  
J. A. Eastman ◽  
K.-C. Chang ◽  
S. K. Kim ◽  
T. T. Fister ◽  
...  
Keyword(s):  
Thin Film ◽  
Surface Exchange ◽  
X Ray ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface
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