Methods of isotopic relaxations for estimation of oxygen diffusion coefficients in solid electrolytes and materials with mixed ionic-electronic conductivity

Sadykov, Vladіslav; Sadovskaya, E. M.; Уваров, Н. Ф.

doi:10.1134/s1023193515050109

Cited by 33 publications

(11 citation statements)

References 23 publications

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“…Depending on temperature and oxygen partial pressure the BSCF perovskites exhibit high oxygen non-stoichiometry (0.3 < δ < 0.8 at 873 < T < 1073 K) [1][2][3][4]. This extraordinary ability to host oxygen vacancies and to transport a significant amount of oxygen anions via oxygen vacancies (with an oxygen diffusion coefficient of about 10 À6 cm 2 /s and ionic conductivity of 0.018 S/cm at 973 K) has been reported for Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 À δ [4][5][6][7][8]. However, significant differences were observed in the structural characteristics and the electrochemical performance of the BSCF solid solutions as a function of temperature (T), atmosphere (inert [9], oxidizing [10][11][12] and reducing [13,14]), as well as of the nature and concentration of A-and B-sites substituents [15][16][17][18].…”

Section: Introductionmentioning

confidence: 85%

Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Maxim¹,

Botea‐Petcu²,

Teodorescu³

et al. 2020

Structure Processing Properties Relationships in Stoichiometric and Nonstoichiometric Oxides

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The mixed conducting perovskite-type oxides BaxSr1-xCo1-yFeyO3-δ (BSCF) are intensively studied as potential high-performance solid oxide fuel cell cathode materials. The effect of different compositional variables and oxygen stoichiometry on the structure and thermodynamic stability of the BaxSr1-xCo1-yFeyO3-δ (x = 0.2, 0.4, 0.5, 0.6, 0.8; y = 0.2, 0.4, 0.6, 0.8, 1) perovskite-type compositions were investigated by solid electrolyte electrochemical cells method and scanning electron microscopy (SEM). The thermodynamic quantities represented by the partial molar free energies, enthalpies and entropies of oxygen dissolution in the perovskite phase, as well as the equilibrium partial pressures of oxygen were obtained in the temperature range of 823–1273 K. The in situ change of oxygen stoichiometry and the determination of thermodynamic parameters of the new oxygen-deficient BSCF compositions were studied via coulometric titration technique coupled with electromotive force (EMF) measurements. The effect of A- and B-site dopants concentration correlated to the variation of oxygen stoichiometry on the thermodynamic stability and morphology of the BSCF samples was evidenced.

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Section: Introductionmentioning

confidence: 85%

Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Maxim¹,

Botea‐Petcu²,

Teodorescu³

et al. 2020

Structure Processing Properties Relationships in Stoichiometric and Nonstoichiometric Oxides

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“…The effluent gases were analyzed by the UGA 200 mass spectrometer (Stanford Research Systems, Sunnyvale, CA, USA). The analysis of 18 O atomic fraction ( α ) and C 16 O 18 O molecular fraction ( f 16-18 ) responses was made for calculating the values of the heteroexchange rate ( R ), oxygen tracer diffusion coefficient ( D * ) and their effective activation energies ( E a,R , E a,D ) using a mathematical model ( Supplementary Materials ) [ 40 , 41 ].…”

Section: Methodsmentioning

confidence: 99%

Carbon Formation during Methane Dry Reforming over Ni-Containing Ceria-Zirconia Catalysts

Smal

Bespalko²,

Arapova³

et al. 2022

Nanomaterials

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Two series of Ni/Ce(Ti/Nb)ZrO2 catalysts were prepared using citrate route and original solvothermal continuous flow synthesis in supercritical isopropanol and studied in dry reforming of methane (DRM). TEM, XPS and FTIRS of adsorbed CO confirm influence of support composition and preparation method on the catalysts’ morphology and surface features. The oxygen mobility was studied by isotope heteroexchange with C18O2. After testing in DRM, carbon deposits after catalysts’ testing in DRM were investigated by temperature-programmed oxidation with thermo-gravimetric analysis. The lowest amounts of carbon deposits were obtained for unmodified Ni-CeZr and Ni-CeNbZr compositions. Ti addition lead to an increased amount of carbon, which was removed at higher temperatures. The use of supercritical supports also resulted in the formation of a higher amount of coke. Catalysts prepared by the supercritical synthesis were tested in DRM for 25 h. The highest activity drop was observed in the first three hours. For all compositions, close values of carbon deposits were revealed.

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“…C 18 O 2 was used as gas-phase 18 O-containing reagent instead of 18 O 2 to avoid problems with limiting by surface exchange since surface exchange rate in the system solid oxide–CO 2 is 2–5 orders of magnitude higher compared to that in the system solid oxide–O 2 due to different exchange mechanisms. − The gas phase composition was analyzed by using UGA-200 mass spectrometer (Stanford Research Systems, USA). Time dependencies of C 16 O 18 O molecules fraction f 16–18 ( t ) and 18 O atoms fraction α( t ) (referred to as isotope kinetic curves) were analyzed by using isotope kinetic equations as described elsewhere. , …”

Section: Methodsmentioning

confidence: 99%

Comparative Study of Electrical Conduction and Oxygen Diffusion in the Rhombohedral and Bixbyite Ln₆MoO₁₂ (Ln = Er, Tm, Yb) Polymorphs

et al. 2019

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Electrical conduction and oxygen diffusion mobility in the bixbyite (Ia3̅ ) and rhombohedral (R3̅ ) polymorphs of the Ln 6 MoO 12−Δ (Ln = Er, Tm, Yb; Δ = δ, δ1, δ2; δ1 > δ2) heavy lanthanide molybdates, belonging to new, previously unexplored classes of potential mixed (ionic−electronic) conductors, have been studied in the range of 200−900 °C. The oxygen selfdiffusion coefficient in bixbyite (Ia3̅ ) Yb 6 MoO 12−δ phase estimated by the temperature-programmed heteroexchange with C 18 O 2 was shown to be much higher than that for rhombohedral (R3̅ ) RI (with large oxygen deficiency) and (R3̅ ) RII (with small oxygen deficiency) Ln 6 MoO 12−Δ (Ln = Tm, Yb; Δ = δ1; δ1 > δ2) oxides. According to the activation energy for total conduction in ambient air, 0.99, 0.93, and 1.01 eV in Er 6 MoO 12−δ , Tm 6 MoO 12−δ, and Yb 6 MoO 12−δ bixbyites, respectively, oxygen ion conductivity prevails in the range ∼200−500 °C. Oxygen mobility data for the rhombohedral Ln 6 MoO 12−Δ (Ln = Er, Tm, Yb; Δ = δ1, δ2) phases RI and RII indicate that the oxygen in these phases exhibits mobility at much higher temperatures, such as those above 600−700 °C. Accordingly, below 600−700 °C they have predominantly electronic conductivity. As shown by total conductivity study of Ln 6 MoO 12−δ (Ln = Er, Tm, Yb) bixbyites (Ia3̅ ) and rhombohedral phases Ln 6 MoO 12−Δ (Ln = Er, Tm, Yb; Δ = δ1, δ2) (R3̅ ) in dry and wet air, the proton conductivity contribution exists only in Ln 6 MoO 12−δ (Ln = Er, Tm, Yb) bixbyites up to 450−600 °C and decreases with a decreasing of the lanthanide ionic radius. The obtained data on the mobility of oxygen and the presence of proton contribution in bixbyites in the 300−600 °C temperature range make it possible to confirm unequivocally that Ln 6 MoO 12−δ (Ln = Er, Tm, Yb) bixbyites are mixed electron−proton conductors at these temperatures.

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Methods of isotopic relaxations for estimation of oxygen diffusion coefficients in solid electrolytes and materials with mixed ionic-electronic conductivity

Cited by 33 publications

References 23 publications

Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Carbon Formation during Methane Dry Reforming over Ni-Containing Ceria-Zirconia Catalysts

Comparative Study of Electrical Conduction and Oxygen Diffusion in the Rhombohedral and Bixbyite Ln₆MoO₁₂ (Ln = Er, Tm, Yb) Polymorphs

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Methods of isotopic relaxations for estimation of oxygen diffusion coefficients in solid electrolytes and materials with mixed ionic-electronic conductivity

Cited by 33 publications

References 23 publications

Thermodynamic Stability and Microscopic Behavior of BaxSr1-xCo1-yFeyO3-δ Perovskites

Thermodynamic Stability and Microscopic Behavior of BaxSr1-xCo1-yFeyO3-δ Perovskites

Carbon Formation during Methane Dry Reforming over Ni-Containing Ceria-Zirconia Catalysts

Comparative Study of Electrical Conduction and Oxygen Diffusion in the Rhombohedral and Bixbyite Ln6MoO12 (Ln = Er, Tm, Yb) Polymorphs

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Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Thermodynamic Stability and Microscopic Behavior of Ba_xSr_1-xCo_1-yFe_yO_3-δ Perovskites

Comparative Study of Electrical Conduction and Oxygen Diffusion in the Rhombohedral and Bixbyite Ln₆MoO₁₂ (Ln = Er, Tm, Yb) Polymorphs