JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Jie Chen,Wenhao Fan,Yachao Wang,Yu Jiang,Saneyuki Ohno,Zuhair A. Munir,Marhoun Ferhat,Shaoping Chen
In this study we investigated the nature and stability of the interfaces between Mg 2.05 Si 0.98 Bi 0.02 as the TE material and Ni and Mg 50 Si 15 Ni 50 as barriers. Single-leg devices of Ni/TE/Ni and Mg 50 Si 15 Ni 50 /TE/Mg 50 Si 15 Ni 50 were prepared by the SPS process in one step and were then subjected to different aging conditions. Using Mg 50 Si 15 Ni 50 as barrier provided a more stable interface with no evidence of an interaction layer. This contrasted with the case when Ni was used as a barrier. The efficiency, η , and the power output, P out , were higher when Mg 50 Si 15 Ni 50 was used as a barrier. The Ni/TE/Ni and Mg 50 Si 15 Ni 50 /TE/Mg 50 Si 15 Ni 50 devices were aged at 673 K for up to 480 h under vacuum and an Mg vapor. For the Mg 50 Si 15 Ni 50 /TE/Mg 50 Si 15 Ni 50 device, the Seebeck coefficient, the efficiency, and power output showed no change with aging time when aging was carried out under in an Mg vapor. The present observations showed that a stable interface can be attained when Mg 50 Si 15 Ni 50 is used as a barrier for the Mg 2.05 Si 0.98 Bi 0.02 TE material .
研究领域:
材料科学
·
热电学
✓ 已验证
产品关联
DOI
高影响因子
Solid Fuel Chemistry
·
2022
·Vol. 56
·期 1
·37-44
·
IF 0.829
Wang Ruiyu,Sun Bingkang,Zhu Jiliang,Fan Xing
Abstract Nano γ-Al 2 O 3 support was prepared by sol-gel method, and the Mg 2 Si/γ-Al 2 O 3 catalyst was prepared by impregnation method from Mg 2 Si and the γ-Al 2 O 3 support. The catalyst was characterized by X-ray diffraction, N 2 adsorption-desorption, scanning electron microscopy and CO 2 temperature-programmed desorption analysis. The catalytic hydrocracking of lignite-related modelcompounds, 1-methoxynaphthalene (1-MON) and bibenzyl ether (BE), was investigated. Mg 2 Si was well distributed on the surface and in the voids of γ-Al 2 O 3 support. The Mg 2 Si/γ-Al 2 O 3 catalyst had high specific surface area, large amount of mesopores, strong basicity, and exhibited high catalytic efficiency in hydrocracking of 1-MON and BE due to the synergic effect between Mg 2 Si and γ-Al 2 O 3 . Under an initial hydrogen pressure of 3 MPa and reaction time of 60 min, the conversion of 1-MON and BE reached 100% when the reaction temperatures were 225 and 175°C, respectively. The selectivities for naphthalene and toluene were close to 100%, only traces of the hydrogenated products were detected. After 4 cycle tests, the catalytic activity of Mg 2 Si/γ-Al 2 O 3 catalystdropped to 50%.
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2022
·Vol. 51
·期 5
·2256-2265
·
IF 2.047
Chen Shaoping,Chen Jie,Fan Wenhao,Wang Yaning,Guo Jingyun,Wang Yachao,Jiang Yu,Al-Yusufi Rasha Abdullah Ahmed,Ferhat Marhoun
Mg 2 SiNi 3, is a topologically densely packed intermetallic compound (TCP-IMC) and an excellent diffusion barrier material between nickel and Mg 2 Si-based thermoelectric material. However, even a little migration of the Mg atom from Mg 2 Si to Mg 2 SiNi 3 under the action of a driven force promotes the formation of an Mg deficiency region on the Mg 2 Si side, which destroys the balance of point defects and leads to performance deterioration. In this work, by adjusting the chemical potential of Mg across the Mg x Si 15 Ni 50 /Mg 2 Si ( x = 36, 50, 130) interface, the migration of Mg in thermoelectric material has been suppressed effectively. The results indicate that the contact performance and service stability of the Mg 130 Si 15 Ni 50 /Mg 2 Si interface has been improved by 50% compared to that of Mg 36 Si 15 Ni 50 /Mg 2 Si, which remains quite well after annealing at 400 ℃ for 480 h. TCP-IMC barrier with proper composition is a promising design for the manufacture of TEG interface to ensure its consistency in service especially under a large temperature difference.
研究领域:
材料科学
·
热电学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2019
·
IF 5.128
Xue-Ke Li,Zhi-Min Zong,Yi-Feng Chen,Zheng Yang,Guang-Hui Liu,Fang-Jing Liu,Xian-Yong Wei,Bao-Jun Wang,Feng-Yun Ma,Jing-Mei Liu
A highly active difunctional Ni-Mg 2 Si/γ-Al 2 O 3 was prepared by thermally decomposing nickel tetracarbonyl onto γ-Al 2 O 3 impregnated with Mg 2 Si. The non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) of the extract ( E ) and extraction residue (ER) from Yinggemajianfeng lignite were investigated over Ni-Mg 2 Si/γ-Al 2 O 3 at 240 °C in n -hexane. Benzyloxybenzene and oxybis(methylene)dibenzene were used as lignite-related model compounds to speculate the possible mechanisms for the catalytic hydrocracking and hydrogenation over Ni-Mg 2 Si/γ-Al 2 O 3 . As a result, more organic matter in ER was converted to soluble portion (SP) by the CHC than by the NCHC. The main SP from the CHC are chain alkanes and cyclanes, while that from the NCHC is rich in arenes and oxygen-containing organic compounds. The results indicate that Ni-Mg 2 Si/γ-Al 2 O 3 effectively catalyze the hydrocracking of >C alk –O– linkages and the hydrogenation of aromatic rings in E and ER.
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2017
·
IF 4.601
Wei-Tu Li,Xian-Yong Wei,Xue-Ke Li,Xiang-Xue Liu,Zhan-Ku Li,Zhi-Min Zong
Catalysts Ni/γ-Al 2 O 3 , Mg 2 Si/γ-Al 2 O 3 , and Ni-Mg 2 Si/γ-Al 2 O 3 were prepared. Their activities for catalytic hydroconversions (CHCs) of some lignite-related model compounds were examined. For the CHCs of oxydibenzene (ODB), benzyloxybenzene, and oxybis(methylene)dibenzene, the suitable loadings of Ni and Mg 2 Si are 33 and 20% in Ni-Mg 2 Si/γ-Al 2 O 3 , respectively, and the optimal reaction conditions are 4 MPa of initial hydrogen pressure, 240 °C, and 2 h, under which ODB was almost completely converted to cyclohexane. The formation of possible intermediates during the CHC of ODB was discussed. Ni-Mg 2 Si/γ-Al 2 O 3 was proposed to have 3 functions, i.e., activating H 2 to biatomic active hydrogen (H⋯H), releasing H − , and heterolytically splitting H⋯H to release H − as well, resulting in the hydrogenation of aromatic rings and the hydrocracking of C O bonds, respectively.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Magnesium and Alloys
·
2025
·
IF 13.8
Shusheng Cao,Yinghui Li,Bolun Wang,Wentao Rao,Yanyue Wang,Hao Du,Dong Wang,Jiaqi Zhang,Xi Lin,Jianxin Zou
The magnesium-silicon hydrogen storage system (Mg 2 Si+H 2 ↔MgH 2 +Si) has attracted considerable attention with the potential of achieving near-room temperature hydrogen sorption since the reaction enthalpy is only ∼36.8 kJ/mol H 2 , offering much better thermodynamic properties over MgH 2 . However, the rehydrogenation of Mg 2 Si faces significant kinetic barriers, restricting its practical utilization. In this work, hydrogen-assisted high-energy ball milling (HHBM) was employed to hydrogenate Mg 2 Si. XRD and HRTEM results confirmed that Mg 2 Si was successfully converted into MgH 2 under the influence of titanium (Ti), achieving a conversion rate up to 76%. Aberration-corrected TEM (AC-TEM) revealed that in situ formed MgH 2 and titanium silicide (TiSi 2 ) were homogenously mixed with robust interfaces. Such a growth mode reduces the migration path of Si atoms and the stability of Mg 2 Si, thus promoting the formation of MgH 2 . Furthermore, the as-synthesized MgH 2 particles with ultrafine particle size and adjacent catalysts show superior thermolysis and hydrolysis performances. Consequently, the composite exhibits excellent hydrogen storage properties, absorbing 50% of its total hydrogen capacity at room temperature and initiating dehydrogenation at 114.3 °C. In situ synchrotron X-ray diffraction (ISXRD) confirms the dehydrogenation of in situ generated ultrafine MgH 2 and part of TiSi 2 is converted to Mg 2 Si at 283 °C. In addition, the ultrafine, defect-rich MgH 2 particles show favorable hydrolysis kinetics and high conversion efficiency at relatively low temperatures (91.9% of the hydrogen yield can be achieved at 5 °C). This method developed in this work exhibits a new way to synthesize high-performance hydrogen storage materials.
研究领域:
材料科学
·
氢气储存
·
固态化学
·
纳米材料
·
能量存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Z.H. Tan,L.Z. Ouyang,J.M. Huang,J.W. Liu,H. Wang,H.Y. Shao,M. Zhu
A convenient, high-density and low-cost hydrogen supply technology is essential to hydrogen energy system by providing hydrogen to fuel cell component. Magnesium silicide (Mg 2 Si) can be a good hydrolysis candidate due to its low cost and ability of releasing hydrogen gas during hydrolysis process. However, previous studies have demonstrated that Mg 2 Si could easily produce large amount of silanes during hydrolysis reaction, which may cause serious problem of explosive danger when in contact with air. Here it is the first time that Mg 2 Si was used for generation of hydrogen by a simple and convenient one-step hydrolysis reaction. In this study, hydrolysis kinetics and mechanisms of Mg 2 Si in NH 4 Cl and NH 4 F solutions were investigated. The silanes could be almost completely turned into hydrogen by introduction of fluorine ion during the hydrolysis reaction of Mg 2 Si, leading to very low silanes content in the produced hydrogen. The kinetic studies indicated that when the concentration of the NH 4 F solution increased to 13.0%, the hydrogen generation rate and the reaction yield were improved significantly and reached the best performance, producing 466 mL g −1 H 2 in 10 min and 616 mL g −1 H 2 in 30 min at 25 °C. The activation energy was calculated to be 37.3 ± 0.8 kJ mol −1 . Furthermore, the hydrogen yield and the hydrolysis rate of Mg 2 Si can be further improved by high-energy ball milling. After ball milling for 2 and 5 h, the hydrogen generation yield in 30 min increased to 698 and 771 mL g −1 , respectively, and the activation energy was decreased to 23.9 ± 0.6 kJ mol −1 and 12.9 ± 0.1 kJ mol −1 , respectively. The results revealed that NH 4 F can be a promising reagent for promoting the hydrolysis of Mg 2 Si for onsite hydrogen supply.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 13
·10904-10910
·
IF 2.324
Wei Jiaming,Duan Bo,Li Jialiang,Yang Houjiang,Chen Gang,Zhai Pengcheng
High pressure high temperature technology is an effective route for preparing thermoelectric materials. In this work, a series of multi-doped Mg 2.02− x Al
x
Si 1−3 y Bi 2 y Sb
y
( x = 0.03, 0.06, y = 0.005, 0.01) compounds have been prepared successfully by high pressure and high temperature method. The effects of post annealing on the microstructure and thermoelectric properties have been investigated. It is found that both electrical conductivity and thermal conductivity are significantly suppressed by annealing. Lower lattice thermal conductivities are observed in Mg 1.96 Al 0.06 Si 1−3 y Bi 2 y Sb
y
compounds, which should be attributed to the increased point-defects phonon scattering of Bi and Sb dopants induced by Al addition. Finally, a maximal figure of merit of 0.9 is achieved by Mg 1.96 Al 0.06 Si 0.985 Bi 0.01 Sb 0.005 at 773 K.
研究领域:
材料科学
·
热电学
·
高压合成
✓ 已验证
DOI
高影响因子
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
·
2020
·Vol. 217
·期 15
·1901035
·
IF 1.759
Shaoping Chen,Yanzuo Chen,Saneyuki Ohno,Libin Xu,Wenhao Fan,Lin Xue,Marhoun Ferhat,Yucheng Wu
The phase component and its evolution during aging at the joint between thermoelectric (TE) materials and electrodes are of much importance to the quality and the performance of the TE devices. While the figure of merit zT of TE materials determines the maximum efficiency of TE devices, undesired side reactions causing the growing interfacial resistance or mechanical failures between TEs and metal electrodes limit the actual performance of devices. Herein, the candidate electrode materials (Mg 2 Ni and Mg 2 SiNi 3 ) for Mg 2 Si are explored, which is one of the cost-effective and environmentally friendly TE materials exhibiting high zT . The electrodes are directly bonded to Mg 2 Si by field-activated pressure-Assisted sintering (FAPAS) in one-step process. The interfaces of fabricated joints with different sintering times are monitored by electron microscopy, followed by the measurement of shear strength and the contact resistances. Outperforming strength (28.29 MPa) and contact resistance (63 μΩ cm 2 ) are observed with Mg 2 SiNi 3 at the joint bonded for 30 min. A long-term stability test on Mg 2 SiNi 3 /Mg 2 Si joint reveals a minute increase in the contact resistance as well as sufficient mechanical stability, suggesting that Mg 2 SiNi 3 is a great candidate of the electrode materials for Mg 2 Si.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
Ceramics-Switzerland
·
2026
·Vol. 9
·期 6
·58
·
IF 2.8
Zizheng Cai,He Ma,Kun Tian,Feng Sun,Lijuan Zhou,Shuang Li
Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg2Si and YH2were used as sintering additives for gas pressure sintering of silicon nitride based on the synergistic mechanism of “silicide silicon extraction-hydride dehydrogenation”. The regulation rules of the additives on ceramic densification, mechanical properties, and thermal conductivity were systematically investigated. Two optimization strategies were proposed for the technical route of replacing traditional oxide additives with non-oxide systems. (i) Rare-earth hydride YH2was used to replace traditional rare-earth oxides. It reacts with SiO2to achieve strong deoxidation and precisely regulate the liquid phase composition. (ii) Metal silicide Mg2Si was used to replace metal oxides. It promotes the preferred growth of β-Si3N4grains, consumes oxygen in the system, and reduces lattice defects. Mg2Si introduces Si into the liquid phase, increasing the Si/O ratio, which lowers lattice oxygen content and supports higher thermal conductivity. YH2consumes SiO2on the Si3N4surface, which reduces liquid phase oxygen content and inhibits lattice oxygen incorporation, promoting a liquid phase with a high N/O ratio. Compared with traditional Y2O3, YH2increases the Y2O3/SiO2ratio in the liquid phase. It promotes grain growth, reduces SiO2activity, and further improves the thermal conductivity of ceramics. Silicon nitride ceramics prepared by gas pressure sintering at 1750 °C with 3 wt.% Mg2Si and 4 wt.% YH2composite additives exhibit the highest thermal conductivity of 87 W/(m·K), with a Vickers hardness of 14.36 GPa and a flexural strength of 643.15 MPa. This study provides an innovative idea for the preparation of high-performance silicon nitride heat dissipation substrates.
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DOI
高影响因子
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