Scientific Reports
·
2021
·Vol. 11
·期 1
·1-11
·
IF 4.38
Wang Jingfeng,Zhang Yue,Liu Fang,Li Qingkui
Considering the problem of high oxygen content in industrial niobium powder, the oxygen reduction of high oxygen niobium powder with the addition of magnesium is studied. Based on the thermodynamic analysis of magnesium thermal reduction of niobium powder, the effects of reduction temperature, magnesium addition, reduction time, and reduction atmosphere on the oxygen content of pickling niobium powder are studied. The results show that with an increase in the magnesium addition, the oxygen content of pickling niobium powder gradually decreases to a certain value, and then remains unchanged. In a certain temperature range (953–1203 K), with an increase in the reduction temperature, the oxygen content of pickling niobium powder first decreases, and then increases; the best oxygen content is 356 ppm at 1133 K. With the extension in reduction time (2–6 h), the oxygen content of pickling niobium powder first decreases, and then remains unchanged. Finally, the oxygen content of pickled niobium powder is reduced to approximately 356 ppm at 400% magnesium addition at 1133 K for 4 h.
研究领域:
材料科学
·
冶金学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ELECTROCHIMICA ACTA
·
2025
·
IF 5.6
Longdi Ma,Yinxiang Han,Xiwen Chen,Yuran Chen,Liqiang Wang,Yangyang Fan,Xuemin Liang,Yapeng Kong
The molten salts electro-deoxidation process, also known as the FFC-Cambridge process, offers substantial potential for the environmentally friendly synthesis of niobium powder in a relatively short process. However, this process suffers from uncontrolled intermediate particle coarsening and the resultant sluggish oxygen-ion diffusion kinetics. To address this, we engineered a novel hierarchically porous Nb 2 O 5 (HPS-Nb 2 O 5 ) cathode with interconnected macropores (∼10 2 μm), mesopores (∼10 1 μm), and micropores (submicron). Electrochemical analyses coupled with potentiostatic electrolysis reveal a four-step reduction pathway of Nb 2 O 5 in molten Na 3 AlF 6 -K 3 AlF 6 -AlF 3 salts: Nb 2 O 5 →Na 2 Nb 8 O 21 /NbO 2 →NbO→Nb, where solid-state oxygen diffusion remains rate-limiting. The novel cathode pore architecture optimizes the solid-liquid interfaces between the cathode and the electrolyte, facilitating uniform insertion of Na⁺/F⁻ ions into cathode particles to generate intermediate particles. Consequently, rhombohedral Na 2 Nb 8 O 21 intermediate with uniform size and morphology was formed, thereby effectively preventing the excessive coarsening of intermediate particles and associated oxygen diffusion path elongation that occurs in the conventional electro-deoxidation processes. Remarkably, complete reduction of 1 g Nb 2 O 5 to Nb powder was achieved in only 1.5 h at 2.5 V. This represents an 8-13-fold efficiency enhancement over the reported processes. The resultant niobium powder exhibits uniform submicron particles (200–500 nm) with near-spherical morphology. This pore-structure-regulated strategy overcomes fundamental bottlenecks in the FFC process and offers broad applicability for the efficient preparation of diverse refractory metals and alloys.
研究领域:
材料科学
·
电化学
·
冶金学
·
纳米技术
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
TRANSACTIONS OF THE INDIAN INSTITUTE OF METALS
·
2025
·Vol. 78
·期 4
·1-11
·
IF 1.6
Chen Qijie,Liu Chencheng,Han Jiaxin,Cheng Yong,Chen Qingyun,Xiong Zhonggang
A new high-entropy MAX phase (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC was successfully synthesized at 1500 ℃ by nonpressure sintering one-step solid phase reaction method. The microstructure, crystal structure and oxidation behavior of high-entropy (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC MAX phase were investigated. Using thermogravimetry analysis to investigate the oxidative stability of (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 ) 2 AlC in air environment at high temperature from 0 to 1000 °C, there is no volume change from 0 to 400 °C, and the morphology still exhibits a typical layered structure, demonstrating thermal stability. Oxidation rate gradually decreases with the increase in temperature, and the K p3 value decreases to 0.86 × 10 –4 kg 2 m −4 s 2 at 1000 ℃. The microscopic morphology analysis at different temperatures shows that the surface defects of the matrix gradually form under high-temperature conditions, in which the formation of carbide and Al 2 O 3 layers hinds the further oxidation of the sample. The research provides a reference for the synthesis and thermal stability of new two-dimensional layered high-entropy MAX ceramics.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2025
·
IF 2.5
Si Guo,Chao Deng,Gang Shi,Dawei Wang,Likui Wang
MXenes are emerging as highly promising materials for pseudocapacitive applications, offering exceptionally high specific capacitance. To date, over 30 distinct MXene compositions and nearly 20 solid solutions have been synthesized in the lab. However, research predominantly centers on Ti3C2Tx and a handful of other single-metal MXenes, with scant attention paid to solid-solution MXenes. Herein, a series of solid solution MAX phases (Nb1−yTiy)4AlC3 and corresponding (Nb1−yTiy)4C3Tx MXenes have been synthesized. The maximum proportion of Ti that can be incorporated into the M site has been examined. We found that the rate performance of MXenes improves with increasing Ti content. Especially, (Nb0.7Ti0.3)4C3Tx and (Nb0.6Ti0.4)4C3Tx retain 62.92% and 68.38% of their capacitances, when the scan rate is increased from 5 mV s−1 to 1000 mV s−1, respectively, compared to Nb4C3Tx's 13.88% retention. (Nb0.7Ti0.3)4C3Tx shows a specific capacitance of 311.06 F g−1 under a current density of 1 A g−1 and good cycling stability. This research demonstrates that the electrochemical characteristics of (Nb1−yTiy)4C3Tx solid solution MXenes can be manipulated by adjusting the ratio of transition metals.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
RARE METALS
·
2024
·
IF 9.6
Zhou Xiao-He,Mo Min-Hua,Chen Zi-Wei,Liu Wen-Jing,Zhang Yan-Li,Pathak Janak L.,Wang Li-Jing,Liu Chang,Shao Long-Quan,Chen Liang-Jiao
Promotion of angiogenesis is crucial for bone tissue repair, and the poor activity of angiogenic cells and growth factors is the main problem in angiogenesis. New proangiogenic nanomaterials are urgently needed to be a promising strategy for this issue. Nb promotes bone formation and fracture healing, possibly by increasing vascular endothelial growth factor (VEGF) production. Nanoniobium particles (nNb) may promote angiogenesis. However, the effect of nNb on angiogenesis is unclear, limiting its application. This study confirmed that nNb significantly promoted angiogenesis. nNb increased and Ras-related C3 botulinum toxin substrate (Rac) family small guanosine triphosphatase (GTPase) 1 (Rac1) expression, inducing F-actin aggregation at the front edge of cells and the formation of pseudopodia to mediate cell migration, further promoting angiogenesis. We discovered that cyclin-dependent kinase-like 5 (CDKL5) is a new signaling molecule that activates Rac1. V-ets erythroblastosis virus E26 oncogene homolog (ETS) domain-containing protein (ELK1), regulating CDKL5 and Rac1, plays an upstream regulatory role. When ELK1 was inhibited, CDKL5 and Rac1 levels were decreased. ELK1, CDKL5 or Rac1 are effective regulatory targets of angiogenesis. Inhibiting expression of ELK1, CDKL5 or Rac1 decreased angiogenesis. Thus, nNb has good angiogenic effects. The ELK1-CDKL5-Rac1 signaling pathway regulates the migration of endothelial cells to promote angiogenesis. nNb can be used in bone tissue engineering as a new nanomaterial, and it will promote the development of a new strategy for tissue engineering. Graphical abstract
研究领域:
材料科学
·
生物医学工程
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细胞生物学
·
组织工程
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED MATERIALS
·
2024
·Vol. 36
·期 48
·2412319
·
IF 27.4
Xitang Qian,Yuxiang Lyu,Siyu Zhou,Yican Qiu,Yan Sun,Yuan Yuan,Minhua Shao
Metal sulfides are increasingly favored as cathode materials in all-solid-state batteries (ASSBs) due to their high energy density, stability, affordability, and conductivity. Metal sulfides often exhibit capacities exceeding their theoretical limits, a phenomenon that remains not fully understood. In this study, it reveals that this phenomenon is primarily due to the sulfur decomposition from sulfide-based electrolyte. By employing the high-energy ball milling (HEBM) technique, the deposition of sulfide-based electrolyte onto sulfur is intentionally promoted, resulting in higher charge capacities compared to the discharge capacities and surpass theoretical limits of metal sulfides. Using chromium sulfide (Cr 2 S 3 ) as the active material, the sulfur decomposed from sulfide-based electrolyte transforms into lithium sulfide (Li 2 S) after discharge, resulting in an increased capacity by ≈439.6 mAh g −1 and improved cycling stability. Consequently, it demonstrates a specific capacity surpassing 1200 mAh g −1 with a capacity retention of over 80% after 650 cycles, maintaining cycling stability for more than 1900 cycles and achieving a Coulombic efficiency exceeding 99.9%. This versatile HEBM approach enables the fabrication of ASSBs utilizing various transition metal sulfides, such as molybdenum disulfide (MoS 2 ), niobium disulfide (NbS 2 ), and iron disulfide (FeS 2 ), all exhibiting over theoretical limited capacities and prolonged cycling capabilities.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACTA MATERIALIA
·
2024
·
IF 8.3
Chaowen Tan,Wansen Ma,Liwen Hu,Qian Li,Xuewei Lv,Jie Dang
As a new type of two-dimensional material, MXenes with increased entropy (ME/HE-MXenes) possess immense potential for exhibiting unforeseen properties, making them a compelling subject for further investigation. However, due to the difficulty in predicting and preparing stable medium-entropy MAX (ME-MAX), as precursors of ME-MXenes, only a few ME-MXenes have been synthesized successfully. Herein, we proposed a thermodynamic competition strategy that enabled the successful synthesis of a stable ME-MAX consisting of four-transition metals: Ti, V, Cr and Nb, which was first predicted by density functional theory calculation. The resulting ME-MAX with a hexagonal crystal structure and pseudo-structure of P 6 3 /mmc, possessed the chemical formula TiVCrNbAlC 3 . Subsequently, the corresponding ME-MXene was prepared by selectively etching the Al layer using HF acid, obtaining the desired composition of Ti 1.1 V 1.1 Cr 0.4 Nb 1.4 C 3 T x . Furthermore, aberration-corrected scanning transmission electron microscopy analysis revealed that the MX slabs within the prepared ME-MXene contained four transition metal layers arranged in an α -configuration, which was consistent with the atomic structure of the ME-MAX. In comparison to single transition metal MXenes, the tailored ME-MXene showcased lattice distortions attributable to the highly diverse composition space, consequently leading to increased active sites and improved electrical conductivity . As a result, the annealed Ti 1.1 V 1.1 Cr 0.4 Nb 1.4 C 3 T x has higher mass capacitances when used as the supercapacitor negative electrode, with weight capacitances of 292.74 F g −1 at 2 mV s −1 and 137.20 F g −1 at 200 mV s −1 . The strategy proposed in this study not only expands the realm of achievable ME-MAX compositions but also opens up new possibilities for derivative medium-entropy MXenes.
研究领域:
材料科学
·
纳米技术
·
电化学
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Yaqi He,Xinhua Li,Zhu Qian,ZuPeng Yan,Guizhen Shi,Xia Sun,Zongqing Ma
In this paper, we innovatively introduced Sn and B into the Nb-Al system at the same time and successfully prepared high-performance Nb 3 Al bulks through mechanical alloying and subsequent low-temperature sintering processes. The influence of different doping amounts of B in the Sn-B co-doping on the superconducting properties of Nb 3 Al superconductors was also investigated. It was found that Sn-B co-doping greatly improves the superconducting properties of Nb 3 Al, especially the J c properties, compared with the undoped sample. The optimal doping amount of Sn-B co-doping is finally determined to be 4 at% Sn-2.6 at% B. At this time, the superconducting transition temperature of Nb 3 Al is up to 16.2 K, and the critical current density reaches up to 1.3 × 10 5 A⋅cm −2 (4.2 K, 5 T), which is almost twice higher than that of Sn-doped Nb 3 Al, and one order of magnitude higher than that of general undoped Nb 3 Al. Combined with the phase composition analysis and microstructure observation, we find that with the co-doping of Sn and B, the grain size of Nb 3 Al is refined, and the diffusely distributed Nb 2 Al nanoparticles are introduced, which greatly enhance the magnetic flux pinning effect of Nb 3 Al. Secondly, the intergranular connectivity of Nb 3 Al is significantly improved. The Sn-B co-doped Nb 3 Al superconductors combine the advantages of Sn doping to enhance flux pinning and B doping to improve intergranular connectivity, which synergistically promotes the dramatic improvement of Nb 3 Al superconductivity Nb 3 Al.
研究领域:
材料科学
·
超导物理
·
金属间化合物
·
凝聚态物理
·
功能材料
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Shuaiqian Wang,Baoji Miao,Muhammad Shahid Nadeem,Huaizhi He,Yao Zhao,Muhammad Yasir,Qiuling Chen,Guoqin Liu,Jinbo Bai
This study successfully prepared a novel high-entropy MAX phase (Ti 1/4 V 1/4 Zr 1/4 Nb 1/4 ) 2 AlC and conducted a comprehensive investigation of its microwave absorption performance. The material was synthesized using a pressure less sintering method, and by optimizing the selection of raw materials and synthesis processes, high purity, and excellent microwave absorption performance were achieved. The composition, structure, morphology, and electromagnetic parameters of the material were analyzed in detail using characterization methods such as XRD, SEM, EDS, TEM, XPS, and vector network analyzer (VNA). Experimental results exhibit that (Ti 1/4 V 1/4 Zr 1/4 Nb 1/4 ) 2 AlC can achieve a lowest RL of -62.56 dB at a thickness of 2.25 mm with frequency of 13.26 GHz, demonstrating outstanding microwave absorption capabilities. The study also explored the microwave absorption mechanisms of grown material, including conductivity, dipole polarization relaxation processes, internal lattice defects, and magnetic loss. This research not only delivers new approaches and development of effective microwave absorption materials but also lays the foundation for subsequent studies on MXene and more multi-element high-entropy MAX phase materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Matter
·
2025
·
IF 17.5
Shining Wu,Yuting Zhang,Guanwu Li,Yifeng Hou,Mengyang Cao,Chengyu Wei,Pengkun Yang,Lu Huang,Yingpeng Wu
High-entropy alloys (HEAs) have a wide range of applications due to their excellent physical and chemical properties. However, traditional synthesis routes always require high temperatures over 923 K or have high equipment requirements. Here, we developed a liquid metal gallium (Ga)-mediated strategy using only a commercial vortex mixer and metal powders to synthesize HEAs near room temperature (303 K) with low power (7 W). A variety of HEAs were successfully prepared, and the yield can be expanded to over 10 g each time. The mechanistic investigation proved that Ga continued to flow under the mechanical force and exposed fresh surfaces to contact the metal, thereby promoting the process of metal dissolution in Ga and forming HEAs. These as-prepared HEAs can be used for catalysis in electrochemical oxygen evolution reactions with low overpotential and high durability. This strategy provides an innovative method for low-energy synthesis of HEAs at room temperature.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Advanced Powder Materials
·
2024
·
IF 28.6
Ziming Ye,Yi Zeng,Xiang Xiong,Sen Gao,Chen Shen,Shiyan Chen,Tianxing Jiang,Ge Yang
Multiphase design is a promising approach to achieve superior ablation resistance of multicomponent ultra-high temperature ceramic (UHTC), while understanding the ablation mechanism is the foundation. Here, through investigating a three-phase multicomponent ceramic consisting of Hf-rich carbide, Nb-rich carbide, and Zr-rich silicide phases, we report a newly discovered solid-state reaction process among multiphase multicomponent ceramic during ablation. It was found that this solid-state reaction occurred in the matrix/oxide scale interface region. In this process, metal cations are counter-diffused between the multicomponent phases, thereby resulting in their composition evolution, which allows the multicomponent phases to exist stably under a higher oxygen partial pressure, leading to the improvement of thermodynamic stability of three-phase multicomponent ceramic. Additionally, this solid-state reaction process appears synergistic with the preferential oxidation behavior among the oxide scale in enhancing the ablation performance.
研究领域:
材料科学
·
高温陶瓷研究
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Shiyong Mou,Siyuan Liu,Weidong Dai,Yanjuan Sun,Fan Dong
Electrochemical oxidative amidation (EOA) strategies offer a sustainable and potentially promising route for amide synthesis. However, the efficiency and activity of catalysts under oxidative conditions are highly dependent on noble metals. Herein, we present our experimental findings and fundamental understanding that fluorine-doped Nb 2 O 5 nanosheet arrays on carbon paper (F-Nb 2 O 5 /CP) serve as an efficient and robust non-noble catalyst for the electrochemical synthesis of formamide from ammonia and methanol under ambient conditions. In 0.5 M KHCO 3 solution, this catalyst achieved a high Faradaic efficiency of 52.0 %, with an N selectivity of 79.1 % at 1.5 V versus Hg/HgO electrode. The catalyst exhibited remarkable stability, maintaining its performance over 120 h. By integrating in-situ spectroscopy studies with density functional theory calculations, we revealed that fluorine doping induces a shift in the d-band center of the Nb site. This shift alters the adsorption behavior of OH - and *NH 2 intermediate on the F-Nb 2 O 5 (100) surface, thereby effectively lowering the C-N coupling energy barrier, and boosting the production of formamide.
研究领域:
材料科学
·
电化学
·
催化化学
✓ 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）