Surface-limited ionic transport in perovskites Sr0.97(Ti,Fe,Mg)O3 − δ

Хартон, В.В.; Viskup, A.P.; Kovalevsky, Andrei V.; Figueiredo, Filipe M.; Jurado, J. R.; Yaremchenko, A.A.; Naumovich, E.N.; Frade, J.R.

doi:10.1039/a909710d

Cited by 51 publications

(51 citation statements)

References 24 publications

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“…The oxygen ionic transport was studied using the measurements of steady-state oxygen permeability (OP) and faradaic ef®ciency (FE), as described elsewhere [12,14,21]. All data on the oxygen permeability presented in this paper correspond to the membrane feed-side oxygen partial pressure (p 2 ) equal to 21 kPa (atmospheric air); the faradaic ef®ciency results were obtained under zero oxygen chemical potential gradient in air [21]. The thickness of the ceramic membranes (d) varied from 0.60 to 2.50 mm.…”

Section: Methodsmentioning

confidence: 99%

Oxygen permeability of LaGa0.65Ni0.20Mg0.15O3−δ ceramics: effect of synthesis method

Shaula¹,

Viskup²,

Хартон³

et al. 2003

Materials Research Bulletin

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Oxygen ionic transport in dense LaGa 0.65 Ni 0.20 Mg 0.15 O 3Àd membranes, prepared by the standard ceramic synthesis technique and via glycine-nitrate process (GNP), was studied using measurements of the total conductivity, oxygen permeation and faradaic ef®ciency (FE). At 1223 K oxygen transfer through LaGa 0.65 -Ni 0.20 Mg 0.15 O 3Àd ceramics is mainly determined by the bulk ambipolar conductivity, while decreasing temperature leads to a greater role of the surface exchange rate. In spite of moderate difference in the ceramic microstructures, the surface exchange limitations are considerably higher for the membranes prepared by the standard ceramic route compared to GNP-synthesized material. Thermal expansion and partial ionic and electronic conductivities were found essentially independent of the synthesis method. The level of oxygen ionic conduction in LaGa 0.65 Ni 0.20 Mg 0.15 O 3Àd , characterized by the activation energy of about 150 kJ/mol and ion transference numbers in the range 1 Â 10 À3 À5 Â 10 À2 at 973±1223 K, is higher than that in La(Ga,Ni)O 3Àd perovskites and comparable to La 2 NiO 4 -based phases. #

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Section: Methodsmentioning

confidence: 99%

Oxygen permeability of LaGa0.65Ni0.20Mg0.15O3−δ ceramics: effect of synthesis method

Shaula¹,

Viskup²,

Хартон³

et al. 2003

Materials Research Bulletin

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“…In many cases when the permeation-limiting role of the surface exchange is significant, the deposition of a catalytically active Pt layer onto the membrane surface leads to a greater oxygen permeability (for example, Refs. [37,38]). For the LSFC/CGO ceramics, the influence of applying such layers is negligible (Fig.…”

Section: Ionic Conductivitymentioning

confidence: 99%

Oxygen transport in Ce0.8Gd0.2O2−-based composite membranes

et al. 2003

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Gadolinia-doped ceria electrolyte Ce 0.8 Gd 0.2 O 2 À d (CGO) and perovskite-type mixed conductor La 0.8 Sr 0.2 Fe 0.8 Co 0.2 O 3 À d (LSFC), having compatible thermal expansion coefficients (TECs), were combined in dual-phase ceramic membranes for oxygen separation. Oxygen permeability of both LSFC and composite LSFC/CGO membranes at 970 -1220 K was found to be limited by the bulk ambipolar conductivity. LSFC exhibits a relatively low ionic conductivity and high activation energy for ionic transport ( f 200 kJ/mol) in comparison with doped ceria. As a result, oxygen permeation through LSFC/CGO composite membranes, containing similar volume fractions of the phases, is determined by the ionic transport in CGO. The permeation fluxes through LSFC/CGO and La 0.7 Sr 0.3 MnO 3 À d /Ce 0.8 Gd 0.2 O 2 À d (LSM/CGO) composites have comparable values. An increase in the p-type electronic conductivity of ceria in oxidizing conditions, which can be achieved by co-doping with variable-valence metal cations, such as Pr, leads to a greater permeability. The oxygen ionic conductivity of the composites consisting of CGO and perovskite oxides depends strongly of processing conditions, decreasing with interdiffusion of the phase components, particularly lanthanum and strontium cations from the perovskite into the CGO phase. D

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“…As discussed below, the oxygen transport through La 1-x Sr x Ga 0.80-y Mg y M 0.20 O 3-δ ceramics at temperatures below 1173 K and membranes thickness less than 1.5 mm is predominantly limited by oxygen exchange on the membrane surface. In the case of significant surface limitations, the apparent values of transference numbers and ionic conductivity may be lower than the true values [14]. However, due to catalytically-active electrode layers applied onto the membrane surface in the case of faradaic efficiency tests, the ion transference numbers determined by this method are essentially unaffected by the surface-exchange processes and are very close to true values [14].…”

Section: Methodsmentioning

confidence: 83%

“…In the case of significant surface limitations, the apparent values of transference numbers and ionic conductivity may be lower than the true values [14]. However, due to catalytically-active electrode layers applied onto the membrane surface in the case of faradaic efficiency tests, the ion transference numbers determined by this method are essentially unaffected by the surface-exchange processes and are very close to true values [14]. In this paper, the ionic transport parameters were calculated from the results of faradaic efficiency measurements with a fixed membrane thickness, 1.00 ± 0.01 mm.…”

Section: Methodsmentioning

confidence: 99%

“…The characterization of ceramic materials included XRD (Rigaku Geigerflex D/MAX-B), scanning electron microscopy combined with energy dispersive analysis (Hitachi S-4100), dilatometry (Linseis L70/2001), measurements of the total conductivity as function of temperature and oxygen partial pressure (4-probe DC), faradaic efficiency studies, and determination of steady-state oxygen permeation fluxes. Detailed description of experimental equipment and procedures was published elsewhere ( [6][7][8][9][10]13,14] and references therein). The oxygen permeation and faradaic efficiency measurements were performed in temperature range 973-1223 K. All data on the oxygen permeability presented in this paper correspond to the membrane feed-side oxygen partial pressure (p 2 ) equal to 21 kPa (atmospheric air).…”

Section: Introductionmentioning

confidence: 99%

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Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O<sub>3-Î´</sub> con metales de transición

Yaremchenko¹,

Shaula²,

Хартон³

et al. 2004

Bol. Soc. Esp. Ceram. Vidr.

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Acceptor-type doping of perovskite-type La 1-x Sr x Ga 0.80-y Mg y M 0.20 O 3-δ (x = 0-0.20, y = 0.15-0.20, M = Fe, Co, Ni) leads to significant enhancement of ionic conductivity and oxygen permeability due to increasing oxygen vacancy concentration. The increase in strontium and magnesium content is accompanied, however, with increasing role of surface exchange kinetics as permeation-limiting factor. At temperatures below 1223 K, the oxygen permeation fluxes through La(Sr)Ga(Mg,M)O 3-δ membranes with thickness less than 1.5 mm are predominantly limited by the exchange rates at membrane surface. The oxygen transport in transition metal-containing La(Sr)Ga(Mg)O 3-δ ceramics increase in the sequence Co < Fe < Ni. The ionic conduction in these phases is, however, lower than that in the parent compounds, La 1-x Sr x Ga 1-y Mg y O 3-δ . The highest level of oxygen permeation, comparable to that of La (Sr) da lugar a una mejora significativa de la conductividad iónica y de la permeabilidad al oxígeno debido al aumento de la concentración de vacantes de oxígeno. Sin embargo, el aumento de la cantidad de estroncio y magnesio viene acompañado de un aumento de la participación de las cinéticas de intercambio superficial como factor limitante de la permeabilidad. A temperaturas por debajo de 1223 K la permeabilidad al flujo de oxígeno a través de las membranas de La(Sr)Ga(Mg,M)O 3-δ con espesor menor de 1.5 mm está limitado principalmente por las velocidades de intercambio en la superficie de la membrana. El transporte de oxígeno en las cerámicas La(Sr)Ga(Mg)O 3-δ que contienen M aumenta en la secuencia Co < Fe < Ni. La conductividad iónica en estas fases es, sin embargo, menor que en la de los compuestos La 1-x Sr x Ga 1-y Mg y O 3-δ . El mayor nivel de permeabilidad de oxígeno, comparable a la de las fases basadas en La(Sr)Fe (

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Surface-limited ionic transport in perovskites Sr0.97(Ti,Fe,Mg)O3 − δ

Cited by 51 publications

References 24 publications

Oxygen permeability of LaGa0.65Ni0.20Mg0.15O3−δ ceramics: effect of synthesis method

Oxygen permeability of LaGa0.65Ni0.20Mg0.15O3−δ ceramics: effect of synthesis method

Oxygen transport in Ce0.8Gd0.2O2−-based composite membranes

Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O<sub>3-Î´</sub> con metales de transición

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