Oxygen self-diffusion in cerium oxide doped with Nd

2001 ◽  
Vol 16 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Michiyo Kamiya ◽  
Eriko Shimada ◽  
Yasuro Ikuma ◽  
Manabu Komatsu ◽  
Hajime Haneda ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Annealing ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Oxygen Diffusion Coefficient ◽  
Self Diffusion ◽  
Surface Exchange Coefficient ◽  
Secondary Ion

Polycrystalline Ce0.77Nd0.23O1.885having a relative density in excess of 98% was prepared. Oxygen diffusion experiments were performed for the temperature range from 750 to 1100 °C, in an oxygen partial pressure of 6.6 kPa. The concentration profile of18O in the specimens following diffusion annealing was measured by secondary ion mass spectroscopy (SIMS). The oxygen self-diffusion coefficient obtained using secondary ion mass spectrometry was expressed by D = 6.31 × 10−9exp(−53 kJ mol−1/RT) m2s−1and was in the extrinsic region. The oxygen diffusion coefficient of Ce0.77Nd0.23O1.885was larger than that of Ce0.8Y0.2O1.90; it was close to those of Ce0.6Y0.4O1.80and Ce0.69Gd0.31O2−δ. The oxygen diffusion coefficient obtained by the tracer method at 700 °C agreed with that calculated from the electrical conductivity in Ce0.77Nd0.23O1.885. The activation energy of the surface exchange coefficient was 94 kJ mol−1, and the values of the surface exchange coefficient were similar to those of stoichiometric CeO2and ThO2.

Oxygen diffusion and surface exchange in the mixed conducting oxides SrTi1−yFeyO3−δ

2016 ◽  
Vol 18 (42) ◽  
pp. 29495-29505 ◽  
Author(s):  
Veronika Metlenko ◽  
WooChul Jung ◽  
Sean R. Bishop ◽  
Harry L. Tuller ◽  
Roger A. De Souza
Keyword(s):  
Oxygen Diffusion ◽  
Oxygen Exchange ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Conducting Oxides ◽  
Single Mechanism ◽  
Surface Exchange Coefficient

Variation of the surface exchange coefficient with Fe concentration suggests single mechanism of oxygen exchange for e−-poor and e−-rich SrTi1−yFeyO3−δ oxides.

Diffusion of Arsenic in Single Crystalline CoSi2

1995 ◽  
Vol 402 ◽  
Author(s):  
A. Pisch ◽  
J. Cardenas ◽  
B. G. Svensson ◽  
C. S. Petersson
Keyword(s):  
Diffusion Coefficient ◽  
Secondary Ion Mass Spectrometry ◽  
Lattice Diffusion ◽  
High Dose ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Different Temperatures ◽  
Secondary Ion ◽  
Self Diffusion Coefficient ◽  
Different Doses

AbstractThe lattice diffusion of arsenic in CoSi2 has been studied in the temperature range from 750°C to 950°C. Two types of bulk samples were used: single crystals prepared by a modified Czochralski pulling technique from a radio frequency levitated melt and polycrystals synthesised by quenching from the melt. The latter samples were subsequently annealed in vacuum at 900°C and displayed grain sizes in the millimetre range. Starting from an ion implanted arsenic profile with two different doses (5·1014 and 5·1015 cm−2) the concentration versus depth profiles after annealing at different temperatures and different times were measured using secondary ion mass spectrometry (SIMS). Contrary to previous studies by other authors substantial diffusion has been observed with an activation energy of 3.3 eV and a pre-exponential factor of 7.37 cm2/s for the diffusion coefficient. These values are very close to the self diffusion coefficient of Si in CoSi2 suggesting that the As atoms migrate via thermal vacancies on nearest neighbour lattice sites by a similar type of mechanism as the Si (and Co) atoms. In the high dose implanted polycrystalline samples arsenic precipitation occurred which gives an estimate for the solid solubility in the 1019 atoms/cm3 range at 800 °C.

Oxygen semi-permeation, oxygen diffusion and surface exchange coefficient of La(1−x)SrxFe(1−y)GayO3−δ perovskite membranes

2010 ◽  
Vol 354 (1-2) ◽  
pp. 6-13 ◽  
Author(s):  
P.M. Geffroy ◽  
J.M. Bassat ◽  
A. Vivet ◽  
S. Fourcade ◽  
T. Chartier ◽  
...  
Keyword(s):  
Oxygen Diffusion ◽  
Exchange Coefficient ◽  
Surface Exchange ◽  
Surface Exchange Coefficient

Oxygen Transport Kinetics in La0.5Sro0.5Fe0.8Ga0.2O3−δ Membranes Under Both Small and Large Oxygen Partial Pressure Gradients

1998 ◽  
Vol 548 ◽  
Author(s):  
Sangtae Kim ◽  
Allan J. Jacobson ◽  
Benjamin Abeles
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Transport ◽  
Oxygen Flow Rate ◽  
Pressure Gradients ◽  
Exchange Coefficient ◽  
Maximum Enhancement ◽  
Surface Exchange ◽  
Surface Exchange Coefficient

ABSTRACTOxygen permeation through a new perovskite La0.5Sr0.5Fe0.8Ga0.2O3−δ membrane has been measured both under small (air/He) and large (air/CO, CO2) oxygen partial pressure gradients. In both cases oxygen transport is close to surface limited. By modeling the pressure dependence of the oxygen flow rate under small pressure gradient an ambipolar diffusion coefficient 9.65 × 10−7cm2/s and a surface exchange coefficient 7.15 × 10−6 cm/s at 974 °C were determined. With air/CO, CO2 on the permeate side, the permeability increases linearly with the partial pressure of CO. The observed increase is greater than the maximum enhancement predicted by our model.

Self-Diffusion in Intrinsic and Extrinsic Silicon Using Isotopically Pure 30Silicon Layer

2001 ◽  
Vol 669 ◽  
Author(s):  
Yukio Nakabayashi ◽  
Hirman I. Osman ◽  
Toru Segawa ◽  
Kazunari Toyonaga ◽  
Satoru Matsumoto ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Intrinsic Diffusion Coefficient ◽  
Intrinsic Diffusion ◽  
Self Diffusion ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTSilicon self–diffusion coefficients were measured in intrinsic and extrinsic silicon from870 to 1070°C using isotopically pure 30Si layer. 30Si diffusion profiles are determined by secondary ion mass spectrometry. The temperature dependence of intrinsic diffusion coefficient in bulk Si isobtained. Comparing it in heavily As-doped or B-doped Si, it is found that Si self-diffusion is entirely mediated by interstitialcy mechanism at lower temperatures below 870°C.

Use of a dynamic gassing-out method for activity and oxygen diffusion coefficient estimation in biofilms

1998 ◽  
Vol 37 (4-5) ◽  
pp. 171-175
Author(s):  
Artem Khlebnikov ◽  
Falilou Samb ◽  
Paul Péringer
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Uptake ◽  
Oxygen Diffusion ◽  
Fixed Bed ◽  
Biofilm Reactor ◽  
Strictly Aerobic ◽  
Comamonas Testosteroni ◽  
Respiration Activity ◽  
Oxygen Diffusion Coefficient ◽  
Biofilm Development

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.

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