Characteristics of mixed conducting perovskites (Ba1−xNdx)Fe3+1−tFe4+tO3−y

Lee, Eunseok

doi:10.1016/j.jiec.2008.02.011

Cited by 9 publications

(4 citation statements)

References 26 publications

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“…The TPR-H 2 results (see below) indicate that Fe(IV) and Fe(III) oxidation states co-exist in the BaFe 1−x Cu x O 3 catalysts, as it is observed that the experimental H 2 consumption is in between the nominal (calculated) H 2 consumption expected, considering that iron as Fe(III) or Fe(IV) is reduced to Fe(II). The presence of Fe(IV) in BaFe 1−x Cu x O 3 catalysts is additionally supported by the well-known stabilization of high oxidation state for B cation, as Fe(IV), in perovskites [19,39,48,49,50]. On the basis of the BaFeO 3 stoichiometric formula, Fe(IV) must be the oxidation state for Fe in the perovskite, and, in the presence of copper, a rise in the Fe(IV) amount and /or the generation of additional oxygen vacancies into the perovskite structure would be expected to compensate the deficiency of positive charge due to the partial iron substitution [19].…”

Section: Resultsmentioning

confidence: 90%

“…The deconvolution of the main band shows two significant contributions at around 709 eV and 711 eV. Even though the identification of iron oxidation states by XPS is very difficult [46], according to literature [39,46,47,48,49,50], the first peak corresponds to Fe(III) species, and the second one could be assigned to Fe(IV) species [48,49,50]. It has been established that the position of the satellite peak is the key finger to detect the oxidation state of Fe [46,48].…”

Section: Resultsmentioning

confidence: 99%

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BaFe1−xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

et al. 2019

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BaFe1−xCuxO3 perovskites (x = 0, 0.1, 0.3 and 0.4) have been synthetized, characterized and tested for soot oxidation in both Diesel and Gasoline Direct Injection (GDI) exhaust conditions. The catalysts have been characterized by BET, ICP-OES, SEM-EDX, XRD, XPS, H2-TPR and O2-TPD and the results indicate the incorporation of copper in the perovskite lattice which leads to: (i) the deformation of the initial hexagonal perovskite structure for the catalyst with the lowest copper content (BFC1), (ii) the modification to cubic from hexagonal structure for the high copper content catalysts (BFC3 and BFC4), (iii) the creation of a minority segregated phase, BaOx-CuOx, in the highest copper content catalyst (BFC4), (iv) the rise in the quantity of oxygen vacancies/defects for the catalysts BFC3 and BFC4, and (v) the reduction in the amount of O2 released in the course of the O2-TPD tests as the copper content increases. The BaFe1−xCuxO3 perovskites catalyze both the NO2-assisted diesel soot oxidation (500 ppm NO, 5% O2) and, to a lesser extent, the soot oxidation under fuel cuts GDI operation conditions (1% O2). BFC0 is the most active catalysts as the activity seems to be mainly related with the amount of O2 evolved during an. O2-TPD, which decreases with copper content.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%

BaFe1−xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

et al. 2019

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“…This volume decrease is well-known for bulk powders of Fe systems [28,29], for ultra-thin films and also found in the present work for 250 nm thick films of BFO. By creating mixed Fe 3+ /Fe 4+ oxidation states an additional electronic conductivity component might be induced (small polaron hopping), in addition to reducing the concentration of the protonic charge carriers, which is why an investigation into the conducting properties, depending on atmosphere and temperature was performed and analyzed in Section 3.4 [30]. To illustrate the process of creating mixed Fe 3+ /Fe 4+ in more detail the following equilibrium reaction in Kröger-Vink notation can be used

V_{O}^{• •} + \frac{1}{2} O_{2} + 2 F e_{F e}^{x} \overset{}{\Leftrightarrow} O_{O}^{x} + 2 F e_{F e}^{•}

where

F e_{F e}^{x}

represents Fe ions in the 3+ valence state and

F e_{F e}^{•}

denotes Fe ions in the 4+ valence state (similar to holes), both on Fe lattice sites.…”

Section: Resultsmentioning

confidence: 99%

“…With Fe present in Fe 3+ /Fe 4+ mixed oxidation states the mechanism of conduction can fundamentally change, which was shown for ultrathin films compared to bulk powders [21]. In addition Lee investigated the change in electrochemical impedance response in different atmospheres and correlated the results with the Fe 4+ ratio contained in the bulk samples [30]. With respect to these findings the measurements in this study were conducted in oxidizing (air) and inert (Ar) atmospheres, as well as under wet and dry conditions.…”

Section: Resultsmentioning

confidence: 99%

Proton Conduction in Grain-Boundary-Free Oxygen-Deficient BaFeO2.5+δ Thin Films

et al. 2017

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Reduction of the operating temperature to an intermediate temperature range between 350 °C and 600 °C is a necessity for Solid Oxide Fuel/Electrolysis Cells (SOFC/SOECs). In this respect the application of proton-conducting oxides has become a broad area of research. Materials that can conduct protons and electrons at the same time, to be used as electrode catalysts on the air electrode, are especially rare. In this article we report on the proton conduction in expitaxially grown BaFeO2.5+δ (BFO) thin films deposited by pulsed laser deposition on Nb:SrTiO3 substrates. By using Electrochemical Impedance Spectroscopy (EIS) measurements under different wet and dry atmospheres, the bulk proton conductivity of BFO (between 200 °C and 300 °C) could be estimated for the first time (3.6 × 10−6 S cm−1 at 300 °C). The influence of oxidizing measurement atmosphere and hydration revealed a strong dependence of the conductivity, most notably at temperatures above 300 °C, which is in good agreement with the hydration behavior of BaFeO2.5 reported previously.

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Synthesis of CdS QDs/BaSnO3 nanocomposites via electrostatic self-assembly for visible light photocatalytic deep oxidation of NO

Song

Cai

et al. 2023

Applied Surface Science

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Characteristics of mixed conducting perovskites (Ba1−xNdx)Fe3+1−tFe4+tO3−y

Cited by 9 publications

References 26 publications

BaFe1−xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

BaFe1−xCuxO3 Perovskites as Active Phase for Diesel (DPF) and Gasoline Particle Filters (GPF)

Proton Conduction in Grain-Boundary-Free Oxygen-Deficient BaFeO2.5+δ Thin Films

Synthesis of CdS QDs/BaSnO3 nanocomposites via electrostatic self-assembly for visible light photocatalytic deep oxidation of NO

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