Synthesis, spark plasma sintering and electrical conduction mechanism in BaTiO3–Cu composites

Yoon, Songhak; Dornseiffer, Juergen; Xiong, Yan; Grüner, Daniel; Shen, Zhijian; Iwaya, Shoichi; Pithan, Christian; Waser, Rainer

doi:10.1016/j.jeurceramsoc.2010.11.012

Cited by 21 publications

(9 citation statements)

References 46 publications

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“…This defect species is reported in oxygen deficient oxides under strongly reducing conditions and may even act as a color center. 64 , 83 − 85 Owing to the electronic structure of CO 2 , the resulting species needs to be a radical (indicated by • in eq 8 ; please do not confuse this with the relative charge in Kröger–Vink notation for point defects). In a following step, the carbonate can be formed by bonding to another surface oxide ion forming a bidentate carbonate: The interpretation of the carbonate as a bidentate is thus a direct consequence of the suggested CO 2 adsorption to a surface vacancy.…”

Section: Resultsmentioning

confidence: 99%

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy

Opitz

Nenning

Rameshan

et al. 2017

ACS Appl. Mater. Interfaces

130

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Any substantial move of energy sources from fossil fuels to renewable resources requires large scale storage of excess energy, for example, via power to fuel processes. In this respect electrochemical reduction of CO2 may become very important, since it offers a method of sustainable CO production, which is a crucial prerequisite for synthesis of sustainable fuels. Carbon dioxide reduction in solid oxide electrolysis cells (SOECs) is particularly promising owing to the high operating temperature, which leads to both improved thermodynamics and fast kinetics. Additionally, compared to purely chemical CO formation on oxide catalysts, SOECs have the outstanding advantage that the catalytically active oxygen vacancies are continuously formed at the counter electrode, and move to the working electrode where they reactivate the oxide surface without the need of a preceding chemical (e.g., by H2) or thermal reduction step. In the present work, the surface chemistry of (La,Sr)FeO3−δ and (La,Sr)CrO3−δ based perovskite-type electrodes was studied during electrochemical CO2 reduction by means of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) at SOEC operating temperatures. These measurements revealed the formation of a carbonate intermediate, which develops on the oxide surface only upon cathodic polarization (i.e., under sufficiently reducing conditions). The amount of this adsorbate increases with increasing oxygen vacancy concentration of the electrode material, thus suggesting vacant oxygen lattice sites as the predominant adsorption sites for carbon dioxide. The correlation of carbonate coverage and cathodic polarization indicates that an electron transfer is required to form the carbonate and thus to activate CO2 on the oxide surface. The results also suggest that acceptor doped oxides with high electron concentration and high oxygen vacancy concentration may be particularly suited for CO2 reduction. In contrast to water splitting, the CO2 electrolysis reaction was not significantly affected by metallic particles, which were exsolved from the perovskite electrodes upon cathodic polarization. Carbon formation on the electrode surface was only observed under very strong cathodic conditions, and the carbon could be easily removed by retracting the applied voltage without damaging the electrode, which is particularly promising from an application point of view.

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Section: Resultsmentioning

confidence: 99%

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy

Opitz

Nenning

Rameshan

et al. 2017

ACS Appl. Mater. Interfaces

130

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“…This is supported by the MgO grain growth observed at a sintering temperature as low as 1100°C. These results can be compared to the work of Yoon et al who prepared BaTiO 3 -Cu composites by SPS [3]. In their work, the copper ductility at low temperature ($400°C) associated to the applied pressure led to the acceleration of sintering during matrix rearrangement.…”

mentioning

confidence: 69%

“…These materials have been widely explored for many technological applications because they exhibit enhanced mechanical, magnetic, optical, or catalytic properties which cannot be achieved with single materials [1]. In the field of electronics and telecommunications, many research programs have focused on nanocomposites composed of Ba 1Àx Sr x TiO 3 (BST) matrix with x = 0 to 1 in which metallic [2,3], polymer [4,5], and ceramic inclusions were added [6,7]. In these works, three issues systematically recur: (i) avoiding interdiffusion and controlling the interfaces; (ii) optimizing inclusion morphology and the sintering behavior of two different materials; (iii) managing the synergy of the final properties.…”

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confidence: 99%

Adjustable dielectric properties of BaTiO 3 containing MgO inclusions deformable under Spark Plasma Sintering

et al. 2016

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“…Although Zhang et al [14] mentioned that the processes of vaporization and condensation might be a predominant mechanism in the solid phase sintering at 300 °C. Some abnormal behavior manifested by mass loss in thermogravimetric analysis was noticed by Yoon et al [28] for SPS sintering of BaTiO3 nanoparticles where copper was used as the matrix phase. They interpreted the chemisorbed water or literarily incorporated hydroxyl ions in the lattice of BaTiO3 as the reason of decreasing mass.…”

Section: Effect Of Sintering Temperature and Composition On Cu Vaporimentioning

confidence: 90%

Vaporization and Poor Wettability as the Main Challenges in Fabrication of TiB2-Cu Cermets Studied by SPS

Ziemnicka-Sylwester

2014

Metals

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TiB2-Cu cermets with various volume fractions of copper (from 3 to 30 vol. %) were produced via liquid phase sintering at the temperature range 1100-1200 °C in vacuum using spark plasma sintering (SPS) technique. Full densification could not be achieved as the consequence of poor wettability and vaporizing Cu. The quantitative Rietveld analysis indicated that insignificant reduction in Cu content occurred only in sample with initially 3 vol. % of Cu, but then densification was negligible. The relative density improved along with increasing volume content of Cu (10-20 vol. %), but then predominant amount of Cu introduced was reduced as the effect of vaporization or swelling, which caused that pellet with intended 20 or 30 vol. % of Cu contained respectively only 6 or 17 vol. % after sintering. Moreover, Cu droplets were released from the die at the temperature of 1000-1030 °C near the Cu melting point. The effect of vaporization was successfully reduced by increased heating rate and when isothermal annealing process was skipped, however, it could not be entirely eliminated. The experimental results on Cu vaporization are confronted with parameters that are commonly considered in the production of cermets, such as oxidation, wettability, contact angle and viscosity as well as their impact on densification.

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Synthesis, spark plasma sintering and electrical conduction mechanism in BaTiO3–Cu composites

Cited by 21 publications

References 46 publications

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy

Adjustable dielectric properties of BaTiO 3 containing MgO inclusions deformable under Spark Plasma Sintering

Vaporization and Poor Wettability as the Main Challenges in Fabrication of TiB2-Cu Cermets Studied by SPS

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Synthesis, spark plasma sintering and electrical conduction mechanism in BaTiO3–Cu composites

Cited by 21 publications

References 46 publications

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO2 Electrolysis Investigated by Operando Photoelectron Spectroscopy

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO2 Electrolysis Investigated by Operando Photoelectron Spectroscopy

Adjustable dielectric properties of BaTiO 3 containing MgO inclusions deformable under Spark Plasma Sintering

Vaporization and Poor Wettability as the Main Challenges in Fabrication of TiB2-Cu Cermets Studied by SPS

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Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy

Surface Chemistry of Perovskite-Type Electrodes During High Temperature CO₂ Electrolysis Investigated by Operando Photoelectron Spectroscopy