Mixed Protonic-Electronic Conductivity of SrCe1-xPrxO3- δ

Abstract Protonic conductors are gaining use in solid oxide fuel cells (SOFCs) and electrolysis cells (SOECs) as well as for H2 separation membranes. However, for SOFC/SOEC electrode and membrane applications their performance is limited by low electronic conductivity. One of the most promising classes of ceramic proton conductors, perovskites, have highly-tunable compositions allowing for the optimization of both ionic and electronic conductivity. In this work Pr-doped SrCeO3 was studied over a wide range of oxygen partial pressures (pO2’s) and temperatures to determine its defect properties and conductivity. Under reducing conditions Pr-doped SrCeO3 was found to be chemically and structurally stable, with an optimal Pr doping level of 10%. This composition shows greater conductivity compared to previously reported Eu-doped SrCeO3. Under low pO2 Pr-doped SrCeO3 exhibited n-type behavior as conductivity increased with decreasing pO2, suggesting that the electronic conductivity of SrCeO3 is significantly enhanced by Pr doping. Under high pO2 conditions, Pr-doped SrCeO3 exhibited p-type conductivity with higher conductivity in the presence of water affirming its protonic conductivity. This work validates the use of Pr as a means of enhancing electronic conductivity in proton conducting perovskites.

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Electrical Conductivity in Praseodymium-Cerium Oxide

MRS Proceedings ◽

10.1557/proc-756-ee10.8 ◽

2002 ◽

Vol 756 ◽

Cited By ~ 2

Author(s):

Todd S. Stefanik ◽

Harry L. Tuller

Keyword(s):

Electrical Conductivity ◽

Ionic Conductivity ◽

Cerium Oxide ◽

Electronic Conductivity ◽

Impurity Band ◽

Defect Model ◽

Valence States ◽

Partial Pressures ◽

Wide Range ◽

Low Levels

ABSTRACTThe electrical conductivity of PrxCe1-xO2-δ (PCO) for 0 ≤ × ≤ 0.20 was examined over a wide range of temperatures and oxygen partial pressures. A defect model based on multiple Pr valence states was found to be qualitatively consistent with the observed data. A unique pO2-dependent ionic conductivity is observed at high pO2 values in compositions containing low levels of Pr (0 ≤ × ≤ 0.01). In compositions containing higher amounts of Pr (0.05 ≤ × ≤ 0.20), formation of a Pr induced impurity band results in a significant electronic conductivity at high pO2 values.

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Effect of Attrition Milling and Calcination Temperature on Phase Composition of Strontium-and Magnesium-Doped Lanthanum Gallate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.727-728.516 ◽

2012 ◽

Vol 727-728 ◽

pp. 516-521 ◽

Cited By ~ 2

Author(s):

S.L. Reis ◽

E.N.S. Muccillo

Keyword(s):

Phase Composition ◽

Solid Oxide Fuel Cells ◽

Calcination Temperature ◽

Lanthanum Gallate ◽

Secondary Phases ◽

Oxygen Ion ◽

Attrition Milling ◽

Oxygen Ion Conductors ◽

Partial Pressures ◽

Wide Range

Oxygen-ion conductors based on strontium-and magnesium-doped lanthanum gallate have been proposed to be used as solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (500-700 °C), due to their high ionic conductivity and stability over a wide range of oxygen partial pressures. In this work, the effect of attrition milling on phase composition of powder and consolidated specimens prepared by solid state synthesis has been investigated. The results show that both the attrition milling and the calcination temperature play a major role in the phase composition. Powders with negligible amount of secondary phases were obtained after two steps of calcination at high temperature followed by attrition milling.

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Comparison of the electrical conductivity of bulk and film Ce1–xZrxO2–δ in oxygen-depleted atmospheres at high temperatures

Journal of Materials Science ◽

10.1007/s10853-021-06348-5 ◽

2021 ◽

Author(s):

Iurii Kogut ◽

Carsten Steiner ◽

Hendrik Wulfmeier ◽

Alexander Wollbrink ◽

Gunter Hagen ◽

...

Keyword(s):

Electrical Conductivity ◽

High Temperatures ◽

Ionic Conduction ◽

Electronic Conductivity ◽

Oxygen Storage ◽

Coarse Grained ◽

Reducing Conditions ◽

Partial Pressures ◽

Microstructural Effects ◽

Defect Interactions

AbstractFeaturing high levels of achievable oxygen non-stoichiometry δ, Ce1−xZrxO2−δ solid solutions (CZO) are crucial for application as oxygen storage materials in, for example, automotive three-way catalytic converters (TWC). The use of CZO in form of films combined with simple manufacturing methods is beneficial in view of device miniaturization and reducing of TWC manufacturing costs. In this study, a comparative microstructural and electrochemical characterization of film and conventional bulk CZO is performed using X-ray diffractometry, scanning electron microscopy, and impedance spectroscopy. The films were composed of grains with dimensions of 100 nm or less, and the bulk samples had about 1 µm large grains. The electrical behavior of nanostructured films and coarse-grained bulk CZO (x > 0) was qualitatively similar at high temperatures and under reducing atmospheres. This is explained by dominating effect of Zr addition, which masks microstructural effects on electrical conductivity, enhances the reducibility, and favors strongly electronic conductivity of CZO at temperatures even 200 K lower than those for pure ceria. The nanostructured CeO2 films had much higher electrical conductivity with different trends in dependence on temperature and reducing atmospheres than their bulk counterparts. For the latter, the conductivity was dominantly electronic, and microstructural effects were significant at T < 700 °C. Nanostructural peculiarities of CeO2 films are assumed to induce their more pronounced ionic conduction at medium oxygen partial pressures and relatively low temperatures. The defect interactions in bulk and film CZO under reducing conditions are discussed in the framework of conventional defect models for ceria.

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Mechanical Properties of LSGM as an Electrolyte for Solid Oxide Fuel Cells

ASME 2008 6th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2008-65151 ◽

2008 ◽

Author(s):

Alidad Mohammadi ◽

Alevtina L. Smirnova ◽

Nigel M. Sammes

Keyword(s):

Mechanical Properties ◽

Solid Oxide Fuel Cells ◽

Morphological Characterization ◽

Solid Oxide ◽

Lanthanum Gallate ◽

Modulus Of Rupture ◽

Oxide Fuel ◽

Electrolyte Layer ◽

Partial Pressures ◽

Wide Range

Strontium- and magnesium-doped lanthanum gallate (LSGM) due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures has been considered as an alternative electrolyte for solid oxide fuel cell (SOFC) systems. Mechanical properties of LSGM electrolyte layer however need to be well studied. An overview of mechanical behavior of LSGM on an all-perovskite SOFC is presented in this work. Dense La0.8Sr0.2Ga0.7Mg0.3O2.8 electrolyte pellets were studied. Mechanical properties, such as hardness, elastic modulus, fracture toughness, and modulus of rupture (MOR) of the electrolyte pellets at different sintering temperatures were measured and correlated with the SEM morphological characterization. Samples sintered for 2h at 1500°C demonstrated slightly enhanced mechanical properties than those sintered at 1450°C and 1400°C.

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Simultaneous Measurement of Ionic and Electronic Conductivities of Conductive Polymers as a Function of Electrochemical Doping in Battery Electrolyte

10.26434/chemrxiv.13133291.v1 ◽

2020 ◽

Author(s):

Billal Zayat ◽

Pratyusha Das ◽

Barry C. Thompson ◽

Sri Narayan

Keyword(s):

Thin Films ◽

Impedance Spectroscopy ◽

Electrical Conduction ◽

Electronic Conductivity ◽

Electrochemical Doping ◽

Electronic Conductivities ◽

Wide Range ◽

Electrochemical Devices ◽

Battery Electrolyte ◽

P Type

We show that the ionic and electronic conductivity of a wide range of p-type and n-type conducting polymer thin films can be reliably measured as a function of electrochemical doping in relevant battery electrolytes by impedance spectroscopy on interdigitated electrodes by combining two separate electrode geometries. The results demonstrate the broad applicability of the methodology for gaining insights into the electrical conduction in polymers in relevant environments, particularly for batteries and other electrochemical devices

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Simultaneous Measurement of Ionic and Electronic Conductivities of Conductive Polymers as a Function of Electrochemical Doping in Battery Electrolyte

10.26434/chemrxiv.13133291 ◽

2020 ◽

Author(s):

Billal Zayat ◽

Pratyusha Das ◽

Barry C. Thompson ◽

Sri Narayan

Keyword(s):

Thin Films ◽

Impedance Spectroscopy ◽

Electrical Conduction ◽

Electronic Conductivity ◽

Electrochemical Doping ◽

Electronic Conductivities ◽

Wide Range ◽

Electrochemical Devices ◽

Battery Electrolyte ◽

P Type

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Profiling of human burned bones: oxidising versus reducing conditions

Scientific Reports ◽

10.1038/s41598-020-80462-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. P. M. Marques ◽

D. Gonçalves ◽

A. P. Mamede ◽

T. Coutinho ◽

E. Cunha ◽

...

Keyword(s):

Inelastic Neutron Scattering ◽

Inelastic Neutron ◽

Skeletal Remains ◽

Anaerobic Conditions ◽

Human Skeletal Remains ◽

Human Bones ◽

Reducing Conditions ◽

Wide Range ◽

Burned Bones ◽

Vibrational Bands

AbstractComplementary optical and neutron-based vibrational spectroscopy techniques (Infrared, Raman and inelastic neutron scattering) were applied to the study of human bones (femur and humerus) burned simultaneously under either aerobic or anaerobic conditions, in a wide range of temperatures (400 to 1000 °C). This is the first INS study of human skeletal remains heated in an oxygen-deprived atmosphere. Clear differences were observed between both types of samples, namely the absence of hydroxyapatite’s OH vibrational bands in bone burned anaerobically (in unsealed containers), coupled to the presence of cyanamide (NCNH2) and portlandite (Ca(OH)2) in these reductive conditions. These results are expected to allow a better understanding of the heat effect on bone´s constituents in distinct environmental settings, thus contributing for an accurate characterisation of both forensic and archaeological human skeletal remains found in distinct scenarios regarding oxygen availability.

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Interfacial defect engineering and Photocatalysis Properties of hBN/MX2(M = Mo, W, and X = S, Se) Heterostructures

Chinese Physics B ◽

10.1088/1674-1056/ac43b2 ◽

2021 ◽

Author(s):

Zhihai Sun ◽

Jiaxi Liu ◽

Ying Zhang ◽

Ziyuan Li ◽

Leyu Peng ◽

...

Keyword(s):

Density Functional ◽

Density Functional Theory Calculations ◽

Band Alignment ◽

Type I ◽

Defect Engineering ◽

Wide Range ◽

Interfacial Defects ◽

Significant Research ◽

P Type ◽

The Impact

Abstract Van der Waals (VDW) heterostructures have attracted significant research interest due to their tunable interfacial properties and potential in a wide range of applications such as electronics, optoelectronic, and heterocatalysis. In this work, the impact of interfacial defects on the electronic structures and photocatalytic properties of hBN/MX2(M = Mo, W, and X = S, Se) are studied using density functional theory calculations. The results reveal that the band alignment of hBN/MX2 can be adjusted by introducing vacancies and atomic doping. The type-I band alignment of the host structure was maintained in the heterostructure with n-type doping in the hBN sublayer. Interestingly, the band alignment changed to the type-II heterostructrue as VB defect and p-type doping was introduced in the hBN sublayer. This could be profitable for the separation of photo-generated electron−hole pairs at the interfaces and is highly desired for heterostructure photocatalysis. In addition, two Z-type heterostructures including hBN(BeB)/MoS2, hBN(BeB)/MoSe2, and hBN(VN)/MoSe2 were achieved, showing reducing band gap and ideal redox potential for water splitting. Our results reveal the possibility of engineering the interfacial and photocatalysis properties of hBN/MX2 heterostructures via interfacial defects.

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A- and B-site doping effect on physicochemical properties of Sr2−xBaxMMoO6 (M = Mg, Mn, Fe) double perovskites — candidate anode materials for SOFCs

Functional Materials Letters ◽

10.1142/s1793604716410022 ◽

2016 ◽

Vol 09 (04) ◽

pp. 1641002 ◽

Cited By ~ 2

Author(s):

Kun Zheng ◽

Konrad Świerczek

Keyword(s):

Physicochemical Properties ◽

Solid Oxide Fuel Cells ◽

Anode Materials ◽

Full Range ◽

Solid Oxide ◽

Double Perovskites ◽

Reducing Conditions ◽

Redox Stability ◽

Very High

In this work, we evaluate the physicochemical properties of Sr[Formula: see text]BaxMMoO6 (M [Formula: see text] Mg, Mn, Fe) double perovskites as alternative anode materials for solid oxide fuel cells, for which the effect of substitution of strontium by barium in a full range of compositions is studied. The crystal structure, microstructure, characterization of transport properties (electrical conductivity, Seebeck coefficient) and oxygen content as a function of temperature, as well as chemical stability in oxidizing and reducing conditions are discussed. Fe- and Mo-containing Sr[Formula: see text]BaxFeMoO6 oxides show very high total conductivities with values of 100–1000 S[Formula: see text][Formula: see text]cm[Formula: see text], while Sr[Formula: see text]BaxMgMoO6 present good redox stability.

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Influence of the Sputtering Technique and Thermal Annealing on YSZ Thin Films for Oxygen Sensing Applications

Coatings ◽

10.3390/coatings11101165 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1165

Author(s):

Emilio Paz Alpuche ◽

Pascal Gröger ◽

Xuetao Wang ◽

Thomas Kroyer ◽

Stefanos Fasoulas

Keyword(s):

Thin Films ◽

Gas Sensors ◽

Electronic Conductivity ◽

Film Surface ◽

Annealing Treatment ◽

Thin Film Surface ◽

Sensing Applications ◽

Partial Pressures ◽

Sensor Current ◽

Oxygen Gas

Yttria-stabilized zirconia (YSZ) thin films were deposited using direct current (reactive and metallic) and radio frequency magnetron sputtering. The effect of the deposition technique and annealing treatment on the microstructure and crystallinity of the thin films was assessed. Using the films produced in this work, oxygen gas sensors were built and their performance under vacuum conditions was evaluated. All the films exhibited a cubic crystalline structure after a post-deposition thermal treatment, regardless of the sputtering technique. When the annealing treatment surpassed 1000 °C, impurities were detected on the thin film surface. The oxygen gas sensors employing the reactive and oxide-sputtered YSZ thin films displayed a proportional increase in the sensor current as the oxygen partial pressure was increased in the evaluated pressure range (5 × 10−6 to 2 × 10−3 mbar). The sensors which employed the metallic-deposited YSZ films suffered from electronic conductivity at low partial pressures.

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