Oxygen Partial Pressure Range Research Articles

Influence of oxygen partial pressure on the passivation and depassivation of super 13Cr stainless steel in high temperature and CO2 rich environment.

The passivation and depassivation characteristics of Super 13Cr stainless steel were examined under a range of oxygen partial pressures within a high-temperature (120 ℃) and high-pressure (3MPa) CO2 atmosphere. We performed comprehensive electrochemical assessments, encompassing open-circuit potential monitoring, electrochemical impedance spectroscopy, and linear polarization resistance analysis, to evaluate the corrosion resistance and passive film stability. The results demonstrate that the addition of low O2 partial pressures enhanced the stability of the passive film, while higher O2 levels led to the loss of the passivation properties of Super 13Cr stainless steel. The study elucidates the pivotal role of oxygen in the corrosion mechanisms affecting Super 13Cr stainless steel, presenting valuable data to enhance for integrity management in severe environmental conditions.

Effect of Temperature and Oxygen Concentration on Corrosion of J55 Steel in an O2/CO2 Environment

ABSTRACTThe corrosion product competition and transformation process of J55 under an O2/CO2 environment in the temperature range of 50–350°C and 0–1 MPa oxygen partial pressure range, respectively, were studied using electrochemical and surface analysis techniques as well as thermodynamic calculations to determine its corrosion rate change law and pitting corrosion phenomenon. This study demonstrates that the uniform corrosion rate of J55 with increasing temperature shows a trend of first increasing, then decreasing, and finally increasing. The transformation of its corrosion products, from FeCO3 into Fe3O4, is consistent with the altering corrosion rate law with increasing temperatures. J55 corrodes faster at 350°C as the O2 partial pressure increases. When the O2 partial pressure is low, the predominant kind of corrosion product that is obtained is FeCO3; when the O2 partial pressure exceeds 0.2 MPa, all corrosion products are transformed into iron oxides. As the oxygen partial pressure increases, J55's corrosion product film becomes increasingly less protective of the substrate, making the substance more vulnerable to corrosion reactions.

Development of V2O3 Nanostructures for Alkali Metal Ion Batteries: A Novel Approach through Mild Metal Vapor Reduction and Interface Engineering.

V2O3 has been extensively researched as a battery electrode material due to its ample reserves and high theoretical capacity. However, the synthesis of valence-sensitive V2O3 presents technical challenges as it requires a strict combination of high-temperature treatment and a narrow range of oxygen partial pressures. This study proposes a gentle Li vapor-assisted thermal reduction method to synthesize pure-phase V2O3 at a relatively low temperature of 480 °C without any hazardous gases. It has been discovered that reducing the temperature also improves the specific surface area of the nanoto-mesoscale hierarchical structures and enhances the reactive sites between their secondary grains. These advantages enable the V2O3 micronano particles to store higher levels of Li+, Na+, and K+, increase ionic transport, and tolerate volume expansion. It demonstrates a significant capacity of 767 mA h g-1 in lithium-ion batteries, 393 mA h g-1 in sodium-ion batteries, and 209 mA h g-1 in potassium-ion batteries. It has also been discovered that the crystal structure of V2O3 is easily adjustable by varying the synthesis temperature, which significantly affects the electrochemical storage mechanism. The V2O3 synthesized at 480 °C with low crystallinity exhibits a notable intercalation reaction, facilitating the electrochemical kinetics of reversible insertion/extraction of Li+, Na+, and K+. In contrast, the highly crystalline sample synthesized at 580 °C displays pseudocapacitance behavior instead of an intercalation reaction. The highly crystalline sample synthesized at 680 °C exhibits a thorough pseudocapacitance reaction possessing the capacitive functionality for the electrochemical storage of Na+ or K+ with larger ion radii. This study describes a new synthesis strategy and rational modification of vanadium-based electrodes for alkali metal ion batteries, leading to the development of reasonably priced rechargeable battery systems with applications extending beyond lithium-ion batteries.

Behavior of calcium lignosulfonate under oxygen pressure acid leaching condition

The behavior of calcium lignosulfonate (CLS) in the oxygen pressure acid leaching process of ZnS concentrate was investigated using total organic carbon assessment (TOC), UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and gas chromatography-coupled mass spectrometry (GC–MS) as characterization methods. The effect of the CLS degradation products on zinc electrowinning was also discussed. The results showed that the temperature was positively correlated with the degradation of CLS, while the initial acidity had only significant effects in the range of 0–50 g/L and oxygen partial pressure range of 0–0.1 MPa. At an oxygen partial pressure of 0.2 MPa, an acidity of 160 g/L, and a reaction temperature of 150 °C, about 82.4% of CLS was degraded. In the oxygen pressure acid leaching process, CLS underwent polymerization and decomposition reactions, and its aromatic rings and side chain groups were damaged to varying degrees. At 120 °C, CLS was partially converted into sulfonic acids, phenols, and esters of higher molecular weights. At 150 °C, CLS further degraded into lower-molecular-weight aromatic ethers and sulfonic acids with shorter carbon chains. These organics were relatively stable and were the main sources of organic compounds during the oxygen pressure leaching process of zinc concentrates. The addition of CLS had a significant negative impact on zinc electrowinning, which was related to the adsorption of CLS on the cathode surface, enhancing cathodic polarization and inhibiting zinc reduction kinetics.

Elucidation of the Transport Properties of Calcium-Doped High Entropy Rare Earth Aluminates for Solid Oxide Fuel Cell Applications.

Solid oxide fuel cells (SOFCs) are paving the way to clean energy conversion, relying on efficient oxygen-ion conductors with high ionic conductivity coupled with a negligible electronic contribution. Doped rare earth aluminates are promising candidates for SOFC electrolytes due to their high ionic conductivity. However, they often suffer from p-type electronic conductivity at operating temperatures above 500°C under oxidizing conditions caused by the incorporation of oxygen into the lattice. High entropy materials are a new class of materials conceptualized to be stable at higher temperatures due to their high configurational entropy. Introducing this concept to rare earth aluminates can be a promising approach to stabilize the lattice by shifting the stoichiometric point of the oxides to higher oxygen activities, and thereby, reducing the p-type electronic conductivity in the relevant oxygen partial pressure range. In this study, the high entropy oxide (Gd,La,Nd,Pr,Sm)AlO3 is synthesized and doped with Ca. The Ca-doped (Gd,La,Nd,Pr,Sm)AlO3 compounds exhibit a higher ionic conductivity than most of the corresponding Ca-doped rare earth aluminates accompanied by a reduction of the p-type electronic conductivity contribution typically observed under oxidizing conditions. In light of these findings, this study introduces high entropy aluminates as a promising candidate for SOFC electrolytes.

Cross-Validation of the Remarkably High Surface Oxygen Exchange Kinetics of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ: A Combined Thin-Film Mass Relaxation and Bulk Electrical Conductivity Relaxation Study.

In this work, we measure the oxygen kinetic properties of double perovskite PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), a material widely used as the air electrode in solid oxide electrochemical cells, by mass relaxation (MR) and electrical conductivity relaxation (ECR) experiments. MR studies are carried out using thin films deposited on a gallium phosphate piezocrystal microbalance, and ECR studies are performed using a bulk bar sample with 97% theoretical density. Measurements are performed at 600 °C over the temperature oxygen partial pressure range from 10-4 to 0.21 atm. Despite the differences in experimental formats and surface microstructural features, the ks values extracted from the two methods are found to be in good agreement with one another. The rate constant is found to increase with oxygen partial pressure with a power law dependence, rising from 1.0 × 10-6 cm/s at 3.2 × 10-4 atm to 1.2 × 10-4 cm/s at 0.24 atm, as averaged over the oxidation and reduction directions. The rates in the oxidation direction are observed to be slightly higher than those in the reduction direction for a given pair of pO2 values, suggesting that the final pO2 value controls the overall relaxation behavior. The power law exponent describing the dependence of ks on pO2 is found to be 0.74 ± 0.01. The ECR study of the bulk sample reveals that even with a diffusion length of 1.8 mm, the relaxation process is largely free of diffusion limitations, indicating that PBSCF has the high bulk transport properties required for a double-phase boundary oxidation/reduction pathway.

The effect of temperature and oxygen partial pressure on the concentration of iron and manganese ions in La1/3Sr2/3Fe1-xMnxO3-δ.

The oxygen content was measured in cubic perovskite-type La1/3Sr2/3Fe1-xMnxO3-δ (x = 0.1, 0.17, 0.25, and 1/3) in the range of oxygen partial pressure from 10-22 to 0.5 atm at 750-950 °C with a step of 50 °C by coulometric titration. Gradual removal of oxygen from the oxides during the measurements was carried out until the stability limit was achieved and the reductive decomposition began. An increase in manganese content was shown to lead to a decrease in the stability of La1/3Sr2/3Fe1-xMnxO3-δ under reducing conditions. The obtained data on oxygen content were used for defect chemistry modeling in the oxides. The enthalpy of the Fe3+ to Fe4+ and Mn3+ to Mn4+ oxidation reactions (ΔHox0) was determined to be -103.2 ± 0.3 and -250 ± 2 kJ mol-1, respectively, for the x = 0.1 composition, and increased slightly with increasing manganese content. The large difference in ΔHox0 determines a strong distinction between the behavior of iron and manganese in perovskite-type oxides. An increase in manganese content in La1/3Sr2/3Fe1-xMnxO3-δ was found to lead to a decrease in the concentration of Fe4+ ions, but did not affect the concentration of Fe2+ ions. The impact of La/Sr ratio was evaluated by comparison of the obtained data with that for La0.5Sr0.5Fe1-xMnxO3-δ, and found to be different for iron and manganese. An increase in lanthanum fraction causes a decrease in the concentration of Fe2+ ions and an increase in the concentration of Mn2+ under reducing conditions.

Phase Transformation of YSZ Electrolyte in Anode-Supported SOFCs

Cubic-stabilized zirconia doped with 8 mol% Y2O3 (8YSZ) is a highly popular electrolyte material for solid oxide fuel cells (SOFCs) due to its exceptional oxide ionic conductivity, which remains consistent across a broad range of oxygen partial pressures. However, previous studies [1,2] have shown that the addition of nickel oxide (NiO) to 8YSZ can expedite the phase transformation process (from cubic to tetragonal) when exposed to a reducing atmosphere at relatively high temperature as 900℃. This phase transformation is closely related to the degradation of 8YSZ's conductivity. Therefore, it is crucial to investigate whether NiO, which should dissolve into the YSZ electrolyte during the co-sintering process with the NiO-YSZ anode at high temperatures, can lead to a similar phenomenon in anode-supported cells (ASCs). Hence, investigating the NiO solid solution phenomenon and its effect on the phase transformation in the YSZ electrolyte of ASCs can offer insights into its degradation behavior.In this study, NiO-YSZ anode support and YSZ electrolyte were co-sintered at 1370℃, 1450℃, and 1550℃, respectively, for 2 hours to fabricate the half-cell samples. Subsequently, these samples were reduced at 900℃ and 700℃, respectively, with a flow of 50ccm dry H2. High-resolution secondary ion mass spectrometry (SIMS) was used to detect the presence of NiO in YSZ, and Raman spectroscopy was used to detect the phase transformation (cubic to tetragonal) occurring in the YSZ.The SIMS results showed that the amount of NiO in the YSZ electrolyte increased with higher sintering temperatures. Moreover, after reducing the cells at 900℃, phase transformation was detected in all samples. However, there was no significant difference among those cells in terms of the degree of phase transformation, which indicated that phase transformation was not accelerated by the increase of dissolved NiO in YSZ. On the other hand, no phase transformation was observed for the cells reduced at 700℃. The mechanism of phase transformation of YSZ in anode-supported SOFCs and its related conductivity degradation will be discussed in the presentation.

Experimental Study and Thermodynamic Modelling of Equilibrium Distributions of Ni, Sn and Zn Between Slag and Black Copper for E-Scrap Recycling Applications

The recycling of waste electronic and electrical equipment (WEEE) and other secondary copper-containing materials through the "black copper" process relies on the selective distribution of metals among the gas, slag, and copper-rich liquid phase. This distribution is controlled by the effective oxidation/reduction potential, often expressed in terms of oxygen partial pressure. Separation of Ni and Sn presents a certain challenge in recycling though black copper route due to similar distribution coefficients over a wide range of oxygen partial pressures and possibly can be improved by optimizing the slag chemistry. This study provides experimental information on the distribution of Ni, Sn, and Zn between fayalite slags or calcium ferrite slags and copper-rich metal at 1250°C. The study uses high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA) techniques along with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for selected measurements of low concentrations. The oxygen partial pressure is controlled by the CO/CO2/Ar gas flow or by measuring the concentration of copper oxide in the slag. The effect of slag composition in terms of Fe/SiO2 or Fe/CaO ratio is studied by using different holding materials, such as silica (SiO2) ampoule, solid spinel (Fe3O4), wüstite (FeO), or dicalcium ferrite (Ca2Fe2O5). The experimental results are compared with literature data and used to optimize thermodynamic models for FactSage® software. The results demonstrate an opportunity for more effective separation of Ni and Sn using at oxidizing stage by using calcium ferrite slag promoting the formation of Sn4+.

Perovskite/Ruddlesden-Popper composite fuel electrode of strontium-praseodymium-manganese oxide for solid oxide cells: An alternative candidate

Ni migrates from cermet fuel electrodes in SOECs at high overpotentials, prompting interest in alternative electrode materials. Ni-free perovskites with mixed ionic and electronic conductivity are being developed as substitutes for Ni-YSZ- or Ni-CGO-cermet fuel electrodes. However, some perovskite electrodes exhibit poor electrocatalytic activity during steam electrolysis. This study focuses on the synthesis, phase evolution, and cation oxidation state of Sr0.5Pr0.5MnO3 (SPM) perovskite under oxidizing and reducing atmospheres. The electrochemical performance of the SPM electrode is investigated at different steam concentrations (3–50% H2O in H2). Rietveld refinement reveals a phase transformation from Pm-3m (221) to I4/mmm (139) in humidified 5% H2 in N2 gas at 800 °C. XPS measurements indicate that the I4/mmm (139) structure contains more oxygen vacancies, enhancing ionic conductivity and electrocatalytic activity. At 610 ◦C, the SPM electrode with the Pm-3m (221) space group exhibits a low polarization resistance of 0.173 Ω cm2 in 50% H2O in H2 gas. However, forming a Ruddlesden-Popper structure increases polarization resistance at higher temperatures due to a low-frequency reaction. Overall, the SPM electrode shows promising electrocatalytic activity across a wide range of oxygen partial pressure, making it a potential fuel electrode in SOECs.

Oxygen exchange and transport properties of the first-order Ruddlesden-Popper phase La2Ni0.9Co0.1O4+δ

The rare earth nickelate La2Ni0.9Co0.1O4+δ (LNCO) was synthesized via the citrate/EDTA method. X-ray powder diffraction confirmed that the material is single-phase and crystallizes in the orthorhombic K2NiF4-type structure. In-situ dc-conductivity and conductivity relaxation measurements on a bar-shaped sample were applied to determine the electronic conductivity as well as the chemical surface exchange coefficient and chemical diffusion coefficient of oxygen from 600 °C to 850 °C and 0.01 ≤ pO2 / bar ≤ 0.1. The results indicate that substitution of nickel with cobalt in La2Ni0.9Co0.1O4+δ leads to significantly higher values of the surface exchange coefficient compared to La2NiO4+δ, while the electronic conductivity is somewhat reduced. The oxygen non-stoichiometry of LNCO was studied by thermogravimetry in the same temperature and oxygen partial pressure range. The measured thermal expansion coefficients of LNCO fit well with those of common solid electrolytes such as GDC and YSZ. Self-diffusion coefficients of oxygen and ionic conductivities were calculated from the experimentally determined diffusivities and the thermodynamic factor of oxygen by using the Nernst-Einstein relation. The results indicate that LNCO offers an attractive option for application as air electrode in solid oxide cells.

Experimental Study of the Combined Effects of Al2O3, CaO and MgO on Gas/Slag/Matte/Spinel Equilibria in the Cu–Fe–O–S–Si–Al–Ca–Mg System at 1473 K (1200ºC) and p(SO2) = 0.25 atm

The combined effects of Al2O3, CaO and MgO slagging components on phase equilibria and thermodynamics in the basic Cu–Fe–O–S–Si system have been evaluated at 1473 K (1200 ºC) and p(SO2) = 0.25 atm for a range of oxygen partial pressures and matte compositions. The experimental technique included high-temperature equilibration of the samples on a spinel substrate under controlled gas atmosphere (CO/CO2/SO2/Ar), followed by rapid quenching and subsequent measurement of the equilibrium phase compositions using Electron Probe X-ray Microanalysis (EPMA). The experimental data have been compared with the results of thermodynamic calculations undertaken using FactSage software and an internal thermodynamic database. Both the experimental results and the calculations results revealed that the presence of Al2O3, CaO and MgO reduced both the sulphur and copper concentrations in the slag phase for a given set of process conditions. The data have been used for further optimisation of the parameters of the thermodynamic database describing multicomponent metallurgical systems. The resulting thermodynamic database is capable of predicting, with high accuracy, the phase equilibria and the distribution of all elements between the phases in the Cu–Fe–O–S–Si–(Al, Ca, Mg) system.Graphical

Quantitative analysis of oxygen partial pressure measurements based on photoacoustic pump-probe imaging

Pump-probe-based photoacoustic imaging is an innovative technique for high-specificity molecular imaging in deep tissues. Compared with conventional photoacoustic imaging, this method effectively eliminates the interference from blood signal and other background signal, enabling the detection of subtle target molecules. Additionally, the manipulating of the time delay between the pump laser and probe laser can facilitate non-invasive mapping of oxygen partial pressure distribution within tissues. To quantify the photoacoustic pump-probe imaging, we use methylene blue as the molecular probe to monitor changes in oxygen partial pressure within a hemoglobin solution. Utilizing a Gaussian noise model, we investigate the relationship between the stability of the triplet-state difference signal and the average number, and also evaluate the error associated with measuring oxygen partial pressure. The results demonstrate that the detection accuracy of the system is better than 33 mmHg (1 mmHg = 133 Pa) in the oxygen partial pressure range of about 300 to 550 mmHg after 200 times of averaging. This research will play a significant role in guiding the further advancement and application of pump-probe-based photoacoustic imaging technology.

Cation-Deficient Ce-Substituted Perovskite Oxides with Dual-Redox Active Sites for Thermochemical Applications.

Identifying thermodynamically favorable and stable non-stoichiometric metal oxides is of crucial importance for solar thermochemical (STC) fuel production via two-step redox cycles. The performance of a non-stoichiometric metal oxide depends on its thermodynamic properties, oxygen exchange capacity, and its phase stability under high-temperature redox cycling conditions. Perovskite oxides (ABO3-δ) are being considered as attractive alternatives to the state-of-the-art ceria (CeO2-δ) due to their high thermodynamic and structural tunability. However, perovskite oxides often exhibit low entropy change compared to ceria, as they generally have one only redox active site, leading to lower mass-specific fuel yields. Herein, we investigate cation-deficient Ce-substituted perovskite oxides as a new class of potential redox materials combining the advantages of perovskites and ceria. We newly synthesized the (CexSr1-x)0.95Ti0.5Mn0.5O3-δ (x = 0, 0.10, 0.15, and 0.20; CSTM) series, with dual-redox active sites comprising Ce (at the A-site) and Mn (at the B-site). By introducing a cation deficiency (∼5%), CSTM perovskite oxides with both phase purity (x ≤ 0.15) and high-temperature structural stability under STC redox cycling conditions are obtained. Thermodynamic properties are evaluated by measuring oxygen non-stoichiometry in the temperature range T = 700-1400 °C and the oxygen partial pressure range pO2 = 1-10-4 bar. The results demonstrate that CSTM perovskite oxides exhibit a composition-dependent simultaneous increase of enthalpy and entropy change with increasing Ce-substitution. (Ce0.20Sr0.80)0.95Ti0.5Mn0.5O3-δ (CSTM20) showed a combination of large entropy change of ∼141 J (mol-O)-1 K-1 and moderate enthalpy change of ∼238 kJ (mol-O)-1, thereby creating favorable conditions for thermochemical H2O splitting. Furthermore, the oxidation states and local coordination environment around Mn, Ce, and Ti sites in the pristine and reduced CSTM samples were extensively studied using X-ray absorption spectroscopy. The results confirmed that both Ce (at the A-site) and Mn (at the B-site) centers undergo simultaneous reduction during thermochemical redox cycling.

Transport properties of LaYbO3-based electrolytes doped with alkaline earth elements

The rapid development of efficient high-temperature electrochemical devices stimulates the search for new electrolytic materials with high conductivity and excellent chemical stability. From this point of view, lanthanum-containing perovskites can be considered as suitable materials for solid oxide fuel cell applications. In this work, the successfully synthesis and comprehensive study of acceptor-doped lanthanum ytterbates, La1–xMxYbO3–δ (M = Ca, Sr, Ba; x = 0, 0.05, 0.1) is described. X-ray diffraction analysis showed all samples to possess an orthorhombic structure with the space group Pna21, whose stability was confirmed at temperatures up to 1000 °C. The high chemical stability of the materials with respect to carbon dioxide and water vapor was confirmed by SEM and XRD methods. The dilatometry data allowed the determination of thermal expansion coefficient values of ceramic samples, which are close to those for conventionally used YSZ electrolytes. The transport properties of the ceramic were studied in a wide range of temperatures (300–900°C) and oxygen partial pressures. It was found that ytterbates doped with 5 and 10 wt.% of strontium and 5 wt.% of barium exhibited the high electrical conductivity among other considered materials. Thus, these materials can be considered as promising proton-conducting electrolytes for various electrochemical devices.

Defect equilibrium and charge transport in R0.25Sr0.75FeO3−δ (R = La, Nd, Y, Ho): The effect of cation type

The perovskite-type oxides of R0.25Sr0.75FeO3−δ series for R = La, Nd, Y, Ho were subjected to X-ray and electron diffraction studies, thermogravimetric and dilatometric measurements. Coulometric titration and four-probe DC techniques were used to obtain data on oxygen content and electrical conductivity of the oxides in the range of oxygen partial pressure from 10−19 to 0.5 atm at 750–950 °C. A decrease in the size of R-cation in R0.25Sr0.75FeO3−δ was found to result in a decrease in the oxygen content in the oxides, thermal expansion, and electrical conductivity. In case of Y and Ho, an extra factor, in addition to the cation radius, affecting the oxide properties, is argued to be the limited oxygen coordination, which promotes local ordering in the respective oxides. This statement was confirmed by electron diffraction study, which detected incommensurate diffuse scattering as the evidence of partial local ordering of cations in the A sublattice in combination with the ordering of oxygen vacancies. This partial local ordering affects strongly functional properties of Y and Ho containing oxides. In particular, oxygen-ion conductivity at 950 °C decreases from 0.328 ± 0.005 to 0.055 ± 0.003 S/cm in response to the substitution of La in R0.25Sr0.75FeO3−δ by Y.

Optimized fabrication of high-quality Nd0.8Sr0.2NiO2 superconducting films by pulsed laser deposition

The discovery of superconductivity in the infinite-layer nickelates has motivated tremendous efforts for its’ significance toward the understanding of superconductivity. However, the synthesis of infinite-layer nickelates is instable and has become a holdback to experimental progress. According to systematic growth with variable conditions, our study suggests that the synthesis of the precursor perovskite Nd0.8Sr0.2NiO3 phase is very crucial for the whole experimental progress, whereas the topotactic reduction has a relative wide window of reduction condition. What is more, the laser fluence is found to be the most critical parameter to produce high quality of precursor perovskite Nd0.8Sr0.2NiO3 phase. In contrast, high quality of Nd0.8Sr0.2NiO3 phase can be achieved with large range of growth temperature and oxygen partial pressure.

Reassessment of thermochemical energy storage in perovskite-like manganites at comparative studies of RP SrCa3Mn3O10-δ vs. orthorhombic Sr0.25Ca0.75MnO3-δ

The structural stability, thermal expansion, oxygen exchange thermodynamics, and thermochemical storage (TCS) capacity of perovskite-like Sr0.25Ca0.75MnO3-δ and Ruddlesden-Popper SrCa3Mn3O10-δ manganites are studied by the combined use of experimental techniques, thermodynamic modeling of the defect formation reactions, and energy calculations utilizing density functional theory (DFT). It is argued that conservative estimates of the storage capacity can be made by the use of the Dulong-Petit limit for high-temperature heat capacity and oxygen partial enthalpy independent of both temperature and oxygen content. The respectively recalculated literature data and the obtained results show that the thermodynamic limit for the TCS capacity (~800 kJ/kg) of Sr0.25Ca0.75MnO3-δ is one of the highest at thermal cycling within the oxygen partial pressure range of 10 −4–0.21 atm. At the same time, the storage capacity of SrCa3Mn3O10-δ achieves only about 600 kJ/kg. The TCS cycling tests demonstrate the stability of SrCa3Mn3O10-δ while a decline in the energy storage capacity is observed for Sr0.25Ca0.75MnO3-δ. According to the EDX analysis, this effect may reflect surface degradation of Sr0.25Ca0.75MnO3-δ. The energy storage capacities of SrCa3Mn3O10-δ and Sr0.25Ca0.75MnO3-δ decrease to 510 and 560 kJ/kg, respectively, because of the rather sluggish reduction kinetics. It is concluded that further improvement of manganites as energy storage materials can be achieved using new doping strategies.

The Surface Tension and Density of Molten Sc_{2}O_{3}, La_{2}O_{3}, Y_{2}O_{3}, Al_{2}O_{3}, and MgO Measured via a Pendant Droplet Method

A thermal imaging furnace (TIF) was used to study the physical properties of molten Sc_{2}O_{3} , La_{2}O_{3}, Y_{2}O_{3}, Al_{2}O_{3} and MgO via a containerless method. The density and surface tension of molten droplets of Sc_{2}O_{3} , La_{2}O_{3}, Y_{2}O_{3}, Al_{2}O_{3}, and MgO suspended from their own solid were measured in situ using live video under a range of oxygen partial pressures (1rightarrow 10^{-6} atm O_{2}). To the best knowledge of the authors, this is the first time the surface tension and density of molten MgO and Sc_{2}O_{3} have been reported. A relationship between molten oxide surface tension and the enthalpy of vaporization is proposed, and a comparison is drawn between the oxide properties and similar relationships previously established for liquid metals.

Strongly coupled oxygen reservoir enabled highly efficient solid oxide fuel cell cathode operation under harsh conditions

The field distribution of oxygen concentration in cathode areas in planar type solid oxide fuel cell stack seriously affects power output, especially at the outlet of/beneath the interconnector where oxygen supply suffers from shortage. A new in-situ solvothermal growth method is applied to prepare gadolinium doped cerium oxide (GDC) nano particles decorated lanthanum strontium cobalt ferrite (LSCF) heterostructure cathode (LSCF@GDC) which performed well under a wide oxygen partial pressure range (0.03–0.21 atm). The cathode shows enhanced specific surface area and improved sintering activity, yielding stronger cathode/electrolyte interface contact. Specifically, the cell equipped with LSCF@GDC cathode demonstrates 40-fold promoted performance under low oxygen partial pressures ( p O 2 = 0.03 a t m ) e.g. 0.415 W/cm 2 for LSCF@GDC versus 0.0107 W/cm 2 for bare LSCF at 750 °C. The systematic characterizations verify that the strong coupling effect between GDC and LSCF, i.e., the GDC serves as the oxygen reservoir to not only alter the crystal structure of LSCF with enhanced oxygen content, but also guarantee sufficient oxygen species for LSCF under oxygen-starving atmosphere. Simultaneously, the oxygen-abundant cathode surface and optimized interface are considered to collectively contribute to the improved electrochemical performances and enable efficient operation. • LSCF@GDC heterostructure cathode is constructed via solvothermal method. • SOFC performance improvement by 40-fold under oxygen partial pressure of 0.03 atm. • Oxygen reservoir effect due to surface anchored GDC nano particles is verified.