JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2021
·Vol. 168
·期 3
·034516
·
IF 4.316
Kai Li,Yafeng Jin,Wenming Gao,Shoucai Xue,Ming Zhang
A critical issue for massive production of metal-supported solid oxide fuel cell is cathode processing due to the contradicting of the metal support and the cathode with regard to the sintering atmosphere. Herein, LSM-BSCF (La0.8Sr0.2MnO3-δ coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ) cathodes on Ni-Fe alloys supported SOFCs (NF-SOFCs) are fabricated by an ex situ sintering approach and electrochemical evaluation in humidified H2 fuel. The ex situ sintering of cathodes on NF-SOFCs are performed at 1050 °C in air with metal oxide support consisted of NiO and 10 at% Fe2O3, and then the oxide support is reduced in situ into Ni-Fe alloys during testing. Cross-section microstructure analysis shows clear evidence that each layer is well adhered to each other after reduction and the suitable microstructure of ex situ sintered cathode is observed after sintering at 1050 °C. In the single-cell test, a higher peak power density is achieved for NF-SOFC with ex situ sintered LSM-BSCF in comparison with in situ sintered cells, revealing a beneficial effect of ex situ sintered cathode on cell performance. The durability measurement and post-test analysis confirm the sufficient adherence and mechanical stability between ex situ sintered LSM-BSCF cathode and GDC (Ce0.9Gd0.1O1.95) electrolyte. The successful electrochemical characterizations of NF-SOFCs with ex situ sintered LSM-BSCF cathode confirm the applicability of the novel sintering procedure.
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JOURNAL OF ELECTRONIC MATERIALS
·
2024
·
IF 2.2
Xu Changji,He Wenbin,Xie Zhuojia,Zou Zhengguang
In this study, La 0.63 Sr 0.2 Nd 0.17 MnO 3 was synthesized by the sol-gel method, and its structural, morphological, magnetic, and magnetocaloric effects were investigated. The structural properties were analyzed by x-ray diffraction (XRD), and scanning electron microscopy (SEM) was used to characterize the morphology. An integrated magnetic measurement system was used to determine the magnetic properties. La 0.63 Sr 0.2 Nd 0.17 MnO 3 crystallized in a hexagonal crystal system with space group R -3 c . This was also confirmed by Rietveld refinement of the x-ray data from La 0.63 Sr 0.2 Nd 0.17 MnO 3 . With the doping of Nd 3+ , the cell volume decreases, which can be explained by the angles and bond lengths of the bonds between the Mn and O ions and the distortion of the lattice. Near the Curie temperature, La 0.63 Sr 0.2 Nd 0.17 MnO 3 exhibits significant magnetocaloric effects. The magnetic study of La 0.63 Sr 0.2 Nd 0.17 MnO 3 suggests that the transition from the paramagnetic to ferromagnetic phase can occur near the Curie temperature. The maximum magnetic entropy change and relative cooling power (RCP) of La 0.63 Sr 0.2 Nd 0.17 MnO 3 (298 K, 3 T) are 2.70 J/(kg K) and 135 (J/kg), respectively. The effect of f -orbitals on the magnetic properties of La 0.8 Sr 0.2 MnO 3 was investigated by first-principles calculations in density functional theory. Thus, it can be concluded that the magnetocaloric effects of the material after doping with f -orbital ions (Nd 3+ ) is enhanced compared to La 0.8 Sr 0.2 MnO 3 .
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CHINESE JOURNAL OF PHYSICS
·
2025
·
IF 4.6
Zhuojia Xie,Fangan Liang,Chuan Ye,Wenbin He,Xiuxin Zheng,Zhengguang Zou
Perovskite manganites stand out as one of the most promising candidate materials for ceramics and room-temperature magnetic refrigeration due to their inherent advantages: excellent chemical stability, low manufacturing cost, straightforward synthesis process, and minimal eddy current losses. However, the broader development and application of these materials in room-temperature magnetic refrigeration have been hampered by their relatively low magnetocaloric properties (MCP) near room temperature. To address this limitation, this study focuses on La 0.8 Sr 0.2 MnO 3 ceramics (LSMO) as a representative perovskite manganite. We systematically enhanced its Curie temperature (Tc) and MCP through A-site rare-earth (RE) ion doping and investigated the doping effects on its MCP and the underlying mechanisms. Key findings reveal that while gradient doping with different RE ions preserved the parent crystal structure, it significantly altered Mn-O bond lengths/angles, unit cell parameters, and the degree of MnO 6 octahedral distortion. Experimental results demonstrate that as the RE ion doping concentration increased, the Tc of La 0.8- x RE x Sr 0.2 MnO 3 ceramics progressively approached room temperature and the magnetic entropy change exhibited a declining trend, yet consistently remained higher than that of the undoped LSMO ceramics. Compared to the undoped LSMO ceramics, A-site RE ion doping effectively tunes the Tc to the vicinity of room temperature and simultaneously enhances the overall MCP. Employing a combined strategy of chemical synthesis and theoretical calculations, we elucidated the “crystal-electronic coupling” mechanism. This mechanism reveals how the synergistic effect of “MnO 6 octahedral lattice distortion” and “ d -orbital electronic structure modulation” governs changes in Tc and MCP. This study's rare-earth A-site doping strategy and “crystal-electronic coupling” mechanism deliver actionable experimental evidence and theoretical frameworks for advancing room-temperature magnetocaloric materials research.
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高影响因子
CRYSTENGCOMM
·
2018
·Vol. 20
·期 43
·7020-7029
·
IF 3.304
Xuehui Huang,Hongyun Pan,Kui Chen,Zhilin Yin,Jing Hong
A molten salt method has been used to prepare porous La0.8Sr0.2Mn1−xCuxO3 (0 ≤ x ≤ 0.4) (LSMC-X) microspheres and La0.8Sr0.2MnO3 (LSM) nanocubes using spherical and cubic MnCO3 as templates, respectively. XRD patterns showed a single perovskite phase when the Cu content was less than x = 0.3. SEM and TEM images indicated that the porous microspheres comprised many aggregated nanoparticles, while the nanocubes were solid with a smooth surface. LSM and LSMC-0 samples both possessed high surface areas (63.5045 and 49.6504 m2 g−1, respectively). Furthermore, the CO conversions showed that LSMC-0.2 had the best catalytic activity (T50 = 83.63 °C, T90 = 97.40 °C) and good stability. XPS analysis confirmed that Cu2+ doping induced Mn4+ formation and slight changes in the oxygen species, leading to different catalytic activity. Owing to their facile synthesis and high catalytic performance, we propose that these porous spherical La0.8Sr0.2Mn1−xCuxO3 (0 ≤ x ≤ 0.4) and nanocubic La0.8Sr0.2MnO3 catalysts are promising candidates for CO oxidation.
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CHINESE JOURNAL OF CATALYSIS
·
2014
·
IF 1.552
Li Meng,Fangzhong Wang,Ao Wang,Jian Pu,Bo Chi,Jian Li
La 0.8 Sr 0.2 MnO 3 (LSM)-coated Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 (BSCF) composite powder (LSM-BSCF) was synthesized by a novel solid-solution method and investigated electrochemically as a cathode material for intermediate temperature solid oxide fuel cells. The cathode combined the merits of LSM and BSCF cathodes through an extended triple phase boundary and stabilized microstructure and demonstrated a polarization resistance between 0.61 and 0.09 Ω cm 2 at 600 to 750 °C. Compared with high performance cathodes prepared by solution impregnation, this LSM-BSCF cathode greatly improved performance stability.
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高影响因子
JOURNAL OF RARE EARTHS
·
2024
·
IF 5.2
Rui Shi,Yan’an Li,Jiutao Gao,Ziyang Chen,Xin Zhang,Shanlin Zhang,Zaheer Ud Din Babar,Chengxin Li
This study focused on meeting the stringent stability requirements of tubular segmented-in-series solid oxide fuel cells (SOFCs) in reducing and oxidizing atmospheres. To address this challenge, a bi-layer perovskite ceramic interconnect was designed by controlling the oxygen partial pressure, because of the strong correlation between the conductivity of strontium-doped lanthanum titanate (LST) and the oxygen partial pressure. The LST powder was prepared using solid-phase and sol-gel methods, and their influence on particle size and sintering behavior was compared. LST/lanthanum strontium manganite (LSM) bi-layer ceramic interconnects with varying thicknesses were fabricated through screen printing and co-sintering. The results demonstrate favorable interfacial bonding and excellent chemical compatibility between the ceramic layers. The conductivity of the bi-layer interconnect exhibits a temperature-dependent behavior, peaking at 550 °C. Simulation calculations and research findings validate that the conductivity of the bi-layer interconnect is determined by the thickness of the LSM layer and the oxygen partial pressure at the interconnect interface. Optimal conductivity is achieved with a bi-layer interconnect consisting of approximately 15 μm of LST and 4 μm of LSM. This can be attributed to the efficient regulation of oxygen partial pressure at the interface, effectively mitigating LSM decomposition caused by low oxygen partial pressure and the subsequent reduction in conductivity. These results provide valuable fundamental data and methodology for the development of high-performance interconnects for tubular segmented-in-series SOFCs.
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高影响因子
APPLIED ENERGY
·
2019
·
IF 8.426
Rong-hua Yuan,Yun He,Wei He,Meng Ni,Michael K.H. Leung
The development of efficient noble-metal free electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great importance for energy storage devices, such as fuel cell and zinc-air battery. In this work, we report a facile approach to enhance the electrocatalytic activity of La 0.8 Sr 0.2 MnO 3 -based perovskite by introducing the deficiency in the A-site and transition-metal Fe in the B-site. Bifunctional electrocatalysts La 0.8 Sr 0.2 MnO 3 , (La 0.8 Sr 0.2 ) 0.98 MnO 3 , (La 0.8 Sr 0.2 ) 0.95 MnO 3 and (La 0.8 Sr 0.2 ) 0.95 Mn 0.5 Fe 0.5 O 3 were prepared by a facile sol–gel process. The material characterization results showed that compared with La 0.8 Sr 0.2 MnO 3 , (La 0.8 Sr 0.2 ) 0.98 MnO 3 and (La 0.8 Sr 0.2 ) 0.95 MnO 3 have smaller particle size, more oxygen vacancies and proper Mn valence, which will benefit both ORR and OER. The results were verified by testing the electrocatalytic activities using rotating-disk electrode (RDE) in alkaline media. For the perovskite oxides with only A-site cation deficiency, the bifunctional electrocatalytic activities increase in the following order: La 0.8 Sr 0.2 MnO 3 < (La 0.8 Sr 0.2 ) 0.98 MnO 3 < (La 0.8 Sr 0.2 ) 0.95 MnO 3 . With partial substitution of Mn by Fe in the B-site, the (La 0.8 Sr 0.2 ) 0.95 Mn 0.5 Fe 0.5 O 3 perovskite oxide exhibits even better electrocatalytic activity. Further experiments reveal that (La 0.8 Sr 0.2 ) 0.95 Mn 0.5 Fe 0.5 O 3 has the highest current density (4.5 mA cm −2 ) in ORR which is comparable to commercial Pt/C (5 mA cm −2 ) and the enhancement of the OER is more obvious than that of the ORR. Subsequently, the perovskite samples were used as the cathode catalysts in zinc-air batteries. The results further prove that proper use of A-site deficiency and B-site Fe doping in perovskite oxides can boost up the electrocatalytic activities.
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