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1.
《Solid State Ionics》2006,177(19-25):2071-2074
(La, Sr)MnO3 (LSM)–Y doped ZrO2 (YSZ) composite was prepared using YSZ colloidal suspension (initial YSZ particle size ∼100 nm), YSZ and LSM polymer precursors on dense substrates at 800 °C annealing temperature. The results of a symmetrical LSM–YSZ composite cell test showed the area specific resistance for overpotential of 0.14 Ω cm2 at 800 °C, which indicated that the LSM–YSZ composite could be a potential candidate for cathode in SOFCs. The performance of the cell with the LSM–YSZ composite cathode and Ni-YSZ anode was investigated and the power density of about 0.26 W cm− 2 was obtained at 850 °C using hydrogen fuel. 相似文献
2.
Composite materials of YSZ (yttria-stabilized zirconia) with various Ni–Fe alloys were synthesized and evaluated as the solid oxide fuel cell (SOFC) anode using a 200-µm thick YSZ electrolyte as support and YSZ +La0.8Sr0.2MnO3 (LSM) as cathode. The single cell with the YSZ + Ni0.75Fe0.25 anode exhibited the highest performance among all the investigated cells, e.g. a peak power density of 403, 337, 218 and 112 mW/cm2 was achieved with H2 fuel at 900, 850, 800 and 750 °C, respectively. The composite anode with the Ni0.75Fe0.25 alloy also had the lowest polarization resistance of 0.55 Ω·cm2 at 800 °C among all the alloy compositions, indicating that this specific alloy offered a better anode composition than pure Ni. The possible mechanism for the improved performance of Ni with the Fe alloying addition towards H2 oxidation was discussed. 相似文献
3.
《Solid State Ionics》2006,177(19-25):1843-1848
The electrochemical performance of La0.58Sr0.4Co0.2Fe0.8O3−δ (L58SCF), La0.9Sr1.1FeO4−δ (LS2F) and LSM (La0.65Sr0.3MnO3−δ)/LSM–YSZ (50 wt.% LSM–50 wt.% ZrO2 (8 mol% Y2O3)) cathode electrodes interfaced to a double layer Ce0.8Gd0.2O2−δ (CGO)/YSZ electrolyte was studied in the temperature range of 600 to 850 °C and under flow of 21% O2/He mixture, using impedance spectroscopy and current density–overpotential measurements. The L58SCF cathode exhibited the highest electrocatalytic activity for oxygen reduction, according to the order: LS2F/CGO/YSZ ≤ LSM/LSM–YSZ/CGO/YSZ < L58SCF/CGO/YSZ. 相似文献
4.
Metal-supported solid oxide fuel cells (SOFCs) are promising due to their good mechanical and thermal properties. Stainless steels are often used as a supporting metal. In this study, the possible use of Ni as a supporting metal was tested. Ni is also a good model of supporting metal due to its lack of Cr which poisons Ni anode.YSZ electrolyte and Ni-YSZ anode were coated on a porous Ni support to fabricate Ni-supported SOFC. A porous Ni support in thick-film form (t ~ 150 µm) was prepared by the mold casting of Ni powders. An anode and an electrolyte layer were sequentially coated on the Ni support using screen printing and tape casting methods, respectively. The Ni-supported cell (t ~ 200 µm) was sintered at 1400 °C in a reducing atmosphere and the performance was evaluated at 800 °C with a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode. The unit cell showed an open circuit voltage (OCV) of 0.96 V and a peak power density of 470 mW/cm2 at 800 °C. 相似文献
5.
Y.L. Liu A. Hagen R. Barfod M. Chen H.J. Wang F.W. Poulsen P.V. Hendriksen 《Solid State Ionics》2009,180(23-25):1298-1304
The changes in the cathode/electrolyte interface microstructure have been studied on anode-supported technological solid oxide fuel cells (SOFCs) that were subjected to long-term (1500 h) testing at 750 °C under high electrical loading (a current density of 0.75 A/cm2). These cells exhibit different cathode degradation rates depending on, among others, the composition of the cathode gas, being significantly smaller in oxygen than in air. FE-SEM and high resolution analytical TEM were applied for characterization of the interface on a submicron- and nano-scale. The interface degradation has been identified as the loss of LSM coverage and the loss of three-phase-boundary (TPB) length. Firstly, the degradation is caused by the size reduction of the individual LSM/YSZ electrolyte contact points (areas) that are initially of 100–200 nm in diameter. Quantitative microstructure evaluation shows that in the cell tested in air this mechanism contributes to an estimated overall reduction in the LSM coverage and the TPB length by 50 and 30%, respectively. For the cell tested in oxygen the corresponding values are 10 and 4%. Secondly, in the cell tested in air the LSM coverage and the TPB length appear to decrease further due to the more pronounced formation of insulating zirconate phases that are present locally and preferably in LSM/YSZ electrolyte contact areas. The effects of the cathode gas on the interface degradation are discussed considering the change of oxygen activity at the interface, possible changes in the Mn diffusion pattern as well as the LSM/YSZ reactivity. Finally, based on thermodynamic calculations a T–p(O2) diagram predicting the safe and risky operation conditions in terms of the zirconate formation is presented and compared with the experimental observations. 相似文献
6.
A fabrication method that does not use lithography or etching processes for thick-film based micro-SOFCs (Solid Oxide Fuel Cells) was described and discussed. In this study, a new type of micro-SOFC was fabricated using a free-standing thick-film electrolyte with ~ 20 μm thickness. This structure has the advantages of both electrolyte-support and electrode-support type SOFCs. Generally, the electrolyte should be thicker than e.g., ~ 150 μm since a thinner electrolyte easily cracks in a self-supporting mode during the fabrication procedure. Thus, a new mounting method was developed in order to use a thin-electrolyte film. In this study, a ~ 20 μm-thick GDC (Gd-doped ceria) electrolyte film was successfully mounted on a ~ 400 μm-thick GDC ring by sintering these two pieces together. Ni-GDC and Sm0.5Sr0.5CoO3 were brush painted as an anode and a cathode, respectively. With this new configuration, it was possible to construct an electrolyte-supported SOFC using a thick-film ceria-based electrolyte and measure the power density. The open-circuit voltage (OCV) of the cell in 97%H2 + 3%H2O/air was ~ 0.87 V and the maximum power density was ~ 270 mW/cm2 at 600 °C. The result shows that the high performance is achievable for the micro-SOFCs using a thick-film ceria-electrolyte operating at 600 °C. 相似文献
7.
Lan Zhang Xinbing Chen San Ping Jiang Hong Quan He Yan Xiang 《Solid State Ionics》2009,180(17-19):1076-1082
Doped lanthanum manganese chromite based perovskite, La0.7A0.3Cr0.5Mn0.5O3 ? δ (LACM, A = Ca, Sr, Ba), on yttria-stabilized zirconia (YSZ) electrolyte is investigated as potential electrode materials for solid oxide fuel cells (SOFCs). The electrical conductivity and electrochemical activity of LACM depend on the A-site dopant. The best electrochemical activity is obtained on the La0.7Ca0.3Cr0.5Mn0.5O3 ? δ/YSZ (LCCM/YSZ) composite electrodes. The conductivity of LCCM is 29.9 S cm? 1 at 800 °C in air, and the electrode polarization resistance (RE) of the LCCM/YSZ composite cathode for the O2 reduction reaction is 0.5 Ω cm2 at 900 °C. The effect of Gd-doped ceria (GDC) impregnation on the LCCM cathode polarization resistances is also studied. GDC impregnation significantly enhances the electrochemical activity of the LCCM cathode. In the case of the 6.02 mg cm? 2 GDC-impregnated LCCM cathode, RE is 0.4 Ω cm2 at 800 °C, ~ 60 times smaller than 24.4 Ω cm2 measured on a LCCM cathode without the GDC impregnation. Finally the electrochemical activities of the doped lanthanum manganese chromites for the H2 oxidation reaction are also investigated. 相似文献
8.
I. Valov V. Rührup R. Klein T.-C. R?del A. Stork S. Berendts M. Dogan H.-D. Wiemh?fer M. Lerch J. Janek 《Solid State Ionics》2009,180(28-31):1463-1470
The ionic and electronic charge transport was studied for single crystals of 9.5 mol% yttria-stabilized zirconia with additional nitrogen doping (YSZ:N) of up to 7.5 at.% (referred to the anion sublattice and formula unit Zr0.83Y0.17O1.91) as a function of temperature and nitrogen content. The total conductivity being almost equivalent to the oxygen ion conductivity has been measured by AC impedance spectroscopy under vacuum conditions in order to prevent re-oxidation and loss of nitrogen. The electronic conductivity has been determined by Hebb–Wagner polarization using ion-blocking Pt microelectrodes in N2 atmosphere. The ionic conductivity of YSZ:N decreases in the presence of nitrogen at intermediate temperatures up to 1000 °C. The mean activation energy of ionic conduction strongly increases with increasing nitrogen content, from 1.0 eV for nitrogen-free YSZ up to 1.9 eV for YSZ containing 7.3 at.% N. Compared to nitrogen-free YSZ, the electronic conductivity first decreases at nitrogen contents of 2.17 and 5.80 at.%, but then increases again for a sample with 7.53 at.%. At temperatures of 850 °C and above, the presence of the N3? dopant fixes the electrode potential and thus the oxygen partial pressure at the Pt electrode to very low values. This corresponds to a pinning of the Fermi level at a relatively high energy in the upper half of the band gap. At 7.53 at.% N and 950 °C, the oxygen partial pressure in YSZ:N corresponds to pO2 = 3 × 10? 18 bar. At temperatures above 850 °C, even in the presence of a very small oxygen concentration in the surrounding gas phase, the nitrogen ion dopant becomes highly mobile and thus diffuses to the surface where it is oxidized to gaseous N2. The results are discussed in terms of the ionic and electronic defect structures and the defect mobilities in YSZ:N. 相似文献
9.
Ni-containing anode is currently used with many electrolytes of solid oxide fuel cells (SOFCs). However, Ni is easily oxidized and deteriorates the LaGaO3-based electrolyte. A La-doped SrTiO3 (LST, La0.2Sr0.8TiO3) is a candidate as an anode material to solve the Ni poisoning problem in LaGaO3-based SOFC. In this study, a single-phase LST and an LST-Gd0.2Ce0.8O2 ? δ (GDC) composite were tested as the possible anodes on La0.9Sr0.1Ga0.8Mg0.2O3 ? δ (LSGM) electrolyte. In order to further improve the anodic performance, Ni was impregnated into the LST-GDC composite anode. The performance was examined from 600 °C to 800 °C by measuring impedance of the electrolyte-supported, symmetric (anode/electrolyte/anode) cells. A polarization resistance (Rp) of LST-GDC anode was much reduced from that of LST anode. When Ni was impregnated into LST-GDC composite, the Rp value was further reduced to ~ 10% of the single-phase LST anode, and it was 1 Ωcm2 at 800 °C in 97% H2 + 3% H2O atmosphere. A single cell with Ni-impregnated LST-GDC as an anode, Ba0.5Sr0.5Co0.8Fe0.2O3 ? δ (BSCF) as a cathode and LSGM as an electrolyte exhibited the maximum power density of 275 mW/cm2 at 800 °C, increased from ~ 60 mW/cm2 for the cell using the LST-GDC as an anode. Thus, LST-GDC composite is promising as a component of anode. 相似文献
10.
《Solid State Ionics》2006,177(19-25):1985-1989
The application of the electrophoretic deposition (EPD) technique to the preparation of high quality electrolyte films for intermediate temperature solid oxide fuel cells (IT-SOFCs) was investigated. Films of La0.83Sr0.17Ga0.83Mg0.17O2.83 (LSGM) were deposited on Pt and La0.8Sr0.2MnO3 (LSM) substrates from suspensions in acetone/ethanol (3:1 by volume) mixture solvent and sintered at 1300 °C. Pt supported LSGM films, 10–20 μm thick, exhibited good adhesion to the Pt substrate, well-distributed microporosity and some surface roughness. LSM supported films exhibited cracking after sintering at 1300 °C for 3 h. Up to 900 °C the bulk conductivity of the Pt supported LSGM film showed the same behaviour of LSGM pellet (Ea = 0.93 eV and 0.99 eV, respectively). The LSGM film exhibited lower bulk electrical conductivity than the latter (4.1 × 10− 3 and 4.4 × 10− 2 Ω− 1 cm− 1, respectively, at 700 °C). This difference should be ascribed to the slight Ga depletion in the LSGM film. An important issue remains the selection of adequate electrode for LSGM electrolyte films. 相似文献
11.
In this work, Ni-10 % Sc2O3-stabilized ZrO2 (SSZ)/SSZ/La0.8Sr0.2MnO3-δ (LSM)-SSZ anode-supported solid oxide fuel cells (SOFCs) have been successfully prepared by tape casting and single-step co-sintering procedures. The structure contains Ni-SSZ anode substrate and Ni-SSZ anode functional, dense SSZ electrolyte, LSM-SSZ cathode functional, and LSM-SSZ cathode layers were successfully prepared at 1250, 1300, and 1350 °C, respectively. The microstructures of the single cells were examined by SEM. There were some close pores in electrolyte of Cell-1250, and the cathode particle size obviously increased in Cell-1350. Therefore, Cell-1300 showed the optimal cell performance, the maximum power density attained 920 mW cm?2 at 800 °C. The impedance analysis demonstrated that the co-sintered temperatures have effects on not only the polarization resistance R P of a single cell but also its overall ohmic resistance R S . The results indicate that the tape casting and single-step co-sintering methods are both time saving and feasible for the development of anode-supported SOFCs. 相似文献
12.
《Solid State Ionics》2009,180(40):1683-1689
The complex perovskite (Pr0.75Sr0.25)1 − xCr0.5Mn0.5O3 − δ (PSCM) has been prepared and studied as possible anode material for high-temperature solid oxide fuel cells (SOFCs). PSCM exhibits GdFeO3-type structure and is both physically and chemically compatible with the conventional YSZ electrolyte. The reduction of PSCM resulted in structural change from orthorhombic Pbnm to cubic Pm-3m. Selected area electron diffraction (SAED) analysis on the reduced phases indicated the presence of a √2 × √2 × 2 superlattice. The total conductivity values of ∼ 75% dense Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ at 900 °C in air and 5% H2/Ar are 9.6 and 0.14 S cm− 1 respectively. The conductivity of PSCM drops with decreasing Po2 and is a p-type conductor at all studied Po2. The average TEC of Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ is 9.3 × 10− 6 K− 1, in the temperature range of 100–900 °C and is close to that of YSZ electrolyte. The anode polarization resistance of PSCM in wet 5%H2 is 1.31 Ω cm2 at 910 °C and in wet CH4 at 930 °C; the polarization resistance is 1.29 Ω cm2. PSCM was unstable at 900 °C in unhumidified hydrogen. Cell performance measurements carried out using graded PSCM and La0.8Sr0.2MnO3 as anode and cathode respectively yielded a maximum power density of 0.18 W cm− 2 in wet 5%H2/Ar at 910 °C and the corresponding current density was 0.44 A cm− 2 at 0.4 V. The activation energy for the electrochemical cell operating in wet (3% H2O) 5%H2/Ar fuel is 85 kJ mol− 1. 相似文献
13.
Preparation and characteristics of Pr1.6Sr0.4NiO4+YSZ as composite cathode of solid oxide fuel cells
Xiqiang Huang Fengmei Zhang Zhe Lü Bo Wei Tingting Li Zhen Wang Wenhui Su 《Journal of Physics and Chemistry of Solids》2009,70(3-4):665-668
Composite cathodes of (1?x wt%)Pr1.6Sr0.4NiO4+(x wt%)Y2O3-stabilized ZrO2 (YSZ; x=0, 10, 20, 30, 40) abbreviated as Pr1.6Sr0.4NiO4+xYSZ, were prepared. The composite cathodes with x>0 matched with electrolyte YSZ in thermal expansion coefficient (TEC) better than the cathode Pr1.6Sr0.4NiO4 did. Pr1.6Sr0.4NiO4+20YSZ exhibited the best performance on cathode overpotential and impedance. When the cathode overpotential was 0.1 V, the polarization current density of Pr1.6Sr0.4NiO4+20YSZ was 0.28 A cm?2, which is about 5.6 times higher than that of Pr1.6Sr0.4NiO4, 0.05 A cm?2. The area-specific resistance (ASR) for Pr1.6Sr0.4NiO4+20YSZ was about 17.7% of that for Pr1.6Sr0.4NiO4 at 750 °C. 相似文献
14.
《Solid State Ionics》2006,177(9-10):931-938
NiO-coated YSZ composite powders were synthesized through the Pechini process in order to improve the performance and durability of SOFC anodes. Their microstructures and electrical properties have been investigated with thermal and redox cycling tests. The coverage of NiO crystals on the YSZ surface could be modulated by controlling the composition of the reaction mixture and the ratio of NiO and YSZ. Ni–YSZ electrodes were manufactured by sintering the die-pressed NiO–YSZ pellet at 1400 °C for 3 h, followed by reducing it to 800 °C under hydrogen atmosphere. The anode made from NiO/YSZ composite powder, which has a high homogeneity and plenty of contact sites between Ni and YSZ, has an excellent tolerance against thermal and redox cycling. The maximum power density of a single cell made from NiO/YSZ composite powder was 0.56 W cm− 2 at 800 °C in reactive gases of humidified hydrogen and air. It can be concluded that the functional NiO/YSZ composite powder will suppress the degradation of anodes and enhance the long-term and redox stability of the unit cell at elevated temperatures. 相似文献
15.
A large difference in thermal expansion coefficient of electrode and electrolyte leads to imperfect electrode/electrolyte interface and hence significant polarization losses in solid oxide fuel cells. To overcome the difficulties associated with electrode and electrode/electrolyte interface, there is need to fabricate the composite cathode. Thus the present paper deals with study of La0.6Sr0.4Co0.2Fe0.8O3−δ(LSCF)–Ce0.9Gd0.1O1.95(GDC) nanocomposite with different fractions of GDC obtained by physical mixing of combustion synthesized nanopowders. No secondary phases were observed upon sintering at 1100 °C for 2 h affirming the chemical compatibility between LSCF and GDC. The composites with relatively high GDC% have higher density as a consequence of rapid grain growth and less conductivity. The nanocomposite with 50% of GDC showed electric conductivity of 30 Scm−1 at 500 °C and low area specific resistance of 106 Ω cm2 with 10 μs relaxation time at 200 °C. 相似文献
16.
New solid electrolytes containing acetamide and lithium bioxalato borate (LiBOB) with different molar ratios have been investigated. Their melting points (Tm) are around 42 °C. The ionic conductivities and activation energies vary drastically below and above Tm, indicating a typical feature of phase transition electrolyte. The ionic conductivity of the LiBOB/acetamide electrolyte with a molar ratio of 1:8 is 5 × 10? 8 S cm? 1 at 25 °C but increases to 4 × 10? 3 S cm? 1 at 60 °C. It was found that anode materials, such as graphite and Li4Ti5O12, could not discharge and charge properly in this electrolyte at 60 °C due to the difficulty in forming a stable passivating layer on the anodes. However, a Li/LiFePO4 cell with this electrolyte can be charged properly after heating to 60 °C, but cannot be charged at room temperature. Although the LiBOB/acetamide electrolytes are not suitable for Li-ion batteries due to poor electrode compatibility, the current results indicate that a solid electrolyte with a slightly higher phase transition temperature than room temperature may find potential application in stationary battery for energy storage where the electrolyte is at high conductive liquid state at elevated temperature and low conductive solid state at low temperature. The interaction between acetamide and LiBOB in the electrolyte is also studied by Raman and FTIR spectroscopy. 相似文献
17.
《Solid State Ionics》2006,177(19-25):2065-2069
Novel Ni–Al2O3 cermet-supported tubular SOFC cell was fabricated by thermal spraying. Flame-sprayed Al2O3–Ni cermet coating played dual roles of a support tube and an anode current collector. Y2O3-stabilized ZrO2 (YSZ) electrolyte was deposited by atmospheric plasma spraying (APS) to aim at reducing manufacturing cost. The gas tightness of APS YSZ coating was achieved by post-densification process. The influence of YSZ coating thickness on the performance of SOFC test cell was investigated in order to optimize YSZ thickness in terms of open circuit voltage of the cell and YSZ ohmic loss. It was found that the reduction of YSZ thickness from 100 μm to 40 μm led to the increase of the maximum output power density from 0.47 W/cm2 to 0.76 W/cm2 at 1000 °C. Using an APS 4.5YSZ coating of about 40 μm as the electrolyte, the test cell presented a maximum power output density of over 0.88 W/cm2 at 1030 °C. The results indicate that SOFCs with thin YSZ electrolyte require more effective cathode and anode to improve performance. 相似文献
18.
《Solid State Ionics》2006,177(11-12):1059-1069
Lanthanum–aluminate-based oxides, (La0.8Sr0.2)1−yAl1−xMnxO3−δ (x = 0, 0.3, 0.5; y = 0 or 0.06) (LSAM), were synthesized and evaluated in detail as potential anode materials for solid oxide fuel cells (SOFCs). The electrical conductivity of LSAM (Mn ≥ 30 mol%) is dominated by p-type electronic conduction and can be treated as a diluted system of lanthanum manganites, (La,Sr)MnO3. At 810 °C, the electrical conductivity of (La0.8Sr0.2)0.94Al0.5Mn0.5O3−δ (LSAM8255b) reaches 12 S/cm in air and 2.7 S/cm in humidified Ar/4% H2 (p(O2) ≈ 10− 18 bar). The thermal expansion coefficients of LSAM8255a and LSAM8255b match YSZ very well and no chemical reaction was observed between these two perovskite materials and YSZ up to at least 1400 °C. Fairly good electrochemical performance was observed for an LSAM8255b–YSZ composite anode. At 850 °C, the polarization resistances are only 0.34 and 0.50 Ω cm2 in wet (∼3% H2O) Ar/20% H2 and wet Ar/20% CH4, respectively. In addition, an exposure to Ar/20% CH4/3% H2O for 35 h did not cause any apparent carbon deposition on the electrode. However, the chemical stability of LSAM8255a and LSAM8255b in a typical anode environment under open circuit conditions does not seem sufficient, leading to performance degradation with time in wet Ar/20% H2 or wet Ar/20% CH4. Furthermore, relatively large chemical expansion (0.3–0.5%) was observed when the atmosphere was switched from air to wet Ar/4% H2, which might cause intolerable stress on the thin film electrolyte layer for a large-area anode-supported planar SOFC, but which might be tolerable for small geometries or electrolyte-supported SOFCs. 相似文献
19.
《Solid State Ionics》2006,177(13-14):1211-1217
La1−xSrxCr1−xMxO3−δ (M = Cr, Fe, V) system has been studied as anode materials for solid oxide fuel cells (SOFCs). The perovskite La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) is stable in both H2 and CH4 atmospheres at temperatures up to 1000°C. However, in the reducing atmospheres of H2 and CH4, its electronic conductivity is greatly reduced from its value in air. We have characterized LSCM as the anode of a SOFC having 250 μm-thick La0.8Sr0.2Ga0.83Mg0.17O2.815 (LSGM) as the electrolyte and SrCo0.8Fe0.2O3−δ (SCF) as the cathode. We report a comparison of the overpotentials at the following anodes: (1) La0.4Ce0.6O1.8 (LDC) + NiO composite in H2, (2) porous LSCM in H2 and CH4, (3) porous LSCM impregnated with CuO in H2 and CH4 and (4) porous LSCM impregnated with CuO and sputtered with Pt in H2 and CH4. An LSCM + CuO + Pt anode gave a maximum power output at 850 °C of 850 mW/cm2 and 520 mW/cm2, respectively, with H2 and CH4 as fuel whereas anode (1) gave 1.4 W/cm2 at 800 °C in H2. There was no noticeable coke formation in CH4 with anodes (2), (3) and (4), which demonstrates that the perovskite oxide is a plausible option for the anode of a SOFC operating with hydrocarbon fuels. We also report the moisture effect in the H2 and CH4 fuel-oxidation process. 相似文献
20.
《Solid State Ionics》2006,177(13-14):1199-1204
Perovskite oxides of the composition BaxSr1−xCo1−yFeyO3−δ(BSCF) were synthesized via a modified Pechini method and characterized by X-ray diffraction, dilatometry and thermogravimetry. Investigations revealed that single-phase perovskites with cubic structure can be obtained for x ≤ 0.6 and 0.2 ≤ y ≤ 1.0. The as-synthesized BSCF powders can be sintered in several hours to nearly full density at temperatures of over 1180 °C. Thermal expansion curves of dense BSCF samples show nonlinear behavior with sudden increase in thermal expansion rate between about 500 °C and 650 °C, due mainly to the loss of lattice oxygen caused by the reduction of Co4+ and Fe4+ to lower valence states. Thermal expansion coefficients (TECs) of BSCF were measured to be 19.2–22.9 × 10− 6 K− 1 between 25 °C and 850 °C. Investigations showed further that Ba0.5Sr0.5Co0.8Fe0.2O3−δ is chemically compatible with 8YSZ and 20GDC for temperatures up to 800 °C, above which severe reactions were detected. After being heat-treated with 8YSZ or 20GDC for 5 h above 1000 °C, Ba0.5Sr0.5Co0.8Fe0.2O3−δ was completely converted to phases like SrCoO3−δ, BaCeO3, BaZrO3, etc. 相似文献