JOURNAL OF POWER SOURCES
·
2019
·
IF 7.467
Qiulin Li,Heng Liu,Long-Cheng Zhang,Hao Chen,Hongjiu Zhu,Yuanke Wu,Maowen Xu,Shu-Juan Bao
Fe-N and pyridinic-N generally are considered the active sites of Fe-N-C catalyst. In this featured work, small uniform Fe/N-rich polymer spheres are selected to prepare the Fe-N-C catalyst and study how the sintering atmosphere (NH 3 , Ar, and H 2 ) to engineer their products. The findings reveal that the sintering atmosphere greatly affected not only the composition , aggregate state, and morphology of Fe, but also the graphitization degree and pore structure of carbon. In addition, XPS results suggest that Fe-N-C-NH 3 possesses the highest Fe-N and pyridinic-N content. Combining its abundant pores, high graphitization, and large specific surface area, the catalyst obtained in NH 3 atmosphere delivers best ORR catalytic performance (E 0 = 0.97 V, E 1/2 = 0.85 V vs RHE), which is even comparable to commercial Pt/C (E 0 = 0.97 V, E 1/2 = 0.83V vs RHE). Moreover, the catalyst exhibits greater stability and methanol resistance than those of Pt/C.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Ruichong Chen,Hao Guo,Zhangyi Huang,Haomin Wang,Jianqi Qi,Mao Zhou,Wei Feng,Tiecheng Lu
Li 4 Si 1–x Ti x O 4 ceramic solid solution was considered as a promising tritium breeding material for fusion reactor blanket. In this work, the effects of the sintering atmosphere on the phase composition, microstructure, and mechanical properties of Li 4 Si 0.7 Ti 0.3 O 4 ceramic pebbles were investigated for the first time, aiming to explore the optimal sintering atmosphere for this solid solution. The results show that compared with air and argon atmosphere, the negative pressure of vacuum atmosphere was more favorable for Ti to enter the Li 4 SiO 4 crystal structure as a substitute for Si atom to form a solid solution. More importantly, sintering in argon-vacuum atmosphere can ensure the formation of solid solution while fully exerting the liquid phase sintering effect. The crushing load of the Li 4 Si 0.7 Ti 0.3 O 4 ceramic pebbles sintered at 800 °C in argon-vacuum atmosphere reaches 30.3 ± 3.2 N. In general, the appropriate sintering atmosphere was of great significance for obtaining Li 4 Si 0.7 Ti 0.3 O 4 solid solution to meet the performance requirements of tritium breeding blanket.
研究领域:
材料科学
·
核能工程
✓ 已验证
产品关联
DOI
高影响因子
AIP Advances
·
2023
·Vol. 13
·期 6
·
IF 1.6
Liu Chang,Mao Runyu,Wu Qiyun,Li Jianlin,Zheng Deyi,Fei Zihao,Pang Chi
In this work, we regulated the oxygen vacancy concentration by sintering BCZT + 0.1 mol % Y + 0.1 mol % Nb [BCZT-0.1 mol % (Y + Nb)] ceramics under air, oxygen, argon, and vacuum atmospheres and examined the effect of oxygen vacancy concentration on phase composition, crystal structure, microstructure, and electrical properties. X-ray photoelectron spectrometry and X-ray diffraction Rietveld refinement showed that the air- and oxygen-sintered ceramic samples had lower oxygen vacancy concentrations, and the oxygen octahedral lattice distortion in the samples was stable when the R-O-T phases coexisted, forming a multiphase coexistence structure with more spontaneous polarization directions. The oxygen-sintering atmosphere is important in oxygen compensation, which promotes the formation of dense microstructure, thereby increasing the Curie temperature ( T C ). Oxygen vacancy formation energy was low in the argon and vacuum atmospheres, and some oxygen vacancies increased the mass transfer effect and grain growth. Nevertheless, excess oxygen vacancies increased the leakage current during polarization resulting in poor polarity, which prevents directional deflection of domains and degrades performance. The vacuum-sintered sample was calcined in 1000 °C air for oxygen supplementation sintering, and as the sintering time increased, the oxygen vacancy concentration decreased, the grains grew further, the density increased, and the piezoelectric properties improved. The oxygen-sintered BCZT-0.1 mol % (Y + Nb) samples had good comprehensive electrical properties ( d 33 = 547 pC/N, k p = 55%, ε r = 5355, P r = 10.63 µ C/cm 2 , E C = 1.89 kV/cm, tan δ = 0.02, and T C = 102 °C).
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
·
2018
·Vol. 28
·期 1
·423-430
·
IF 1.34
Wang Bin,Du Jinjing,Gao Shoukun,Fang Zhao,Zhu Jun,Li Linbo
NiFe 2 O 4 /nano-TiN ceramics were fabricated by a two-step cold-pressing sintering process. Effect of sintering atmosphere (air, nitrogen, argon) on the synthesis process of NiFe 2 O 4 /nano-TiN ceramics was investigated. The DSC-TG and XRD analysis results indicated that besides principal phases of NiO and NiFe 2 O 4 , new-phase Ni 3 TiO 5 formed in the sintered ceramics under the three sintering atmospheres, and metallic phase including iron and nickel appeared in the sintered samples with inert gas (nitrogen, argon) sintering condition. Microstructure analysis results showed that considerable quantity of micropores appeared in the ceramic samples sintered under inert gases (argon, nitrogen), but lower porosity (3.0, 3.6%) and higher densities (4.78 g/cm 3 , 4.51 g/cm 3 ) can be obtained, comparing to the both values (14.4%, 4.17 g/cm 3 ) for the ceramic samples sintered under air atmosphere. Besides, the average bending strength and elastic modulus of the samples sintered under argon is 113.75 MPa and 7.13GPa, which is higher than that of 75.12 MPa, 5.42GPa and 91.96 MPa, 6.26GPa for the samples synthesized under air and nitrogen, separately. When changing sintering atmosphere from air to inert gases (argon, nitrogen), the fracture model of the 4 wt.%nano-TiN/NiFe 2 O 4 ceramics synthesized at 1400 °C for 4 h transformed from intergranular fracture to intergranular-transgranular fracture.
研究领域:
材料科学
·
陶瓷工程
·
固态化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）