ELECTROCHIMICA ACTA
·
2018
·
IF 5.116
Qingfeng Zhou,Junzheng Wang,Rurong Zheng,Yun Gong,Jianhua Lin
Two chromite spinel-based composite materials, Mn II Cr III 2 O 4 /Mn II Mn III 2 O 4 /C and CoCr 2 O 4 /C are successfully synthesized by a solid-state conversion process via annealing Mn Cr-coordination compound and Co Cr-coordination compound at 350 °C in air for 1 h, respectively. The two composite materials both show the morphology of nanoparticles , in which the spinels are embedded in carbon matrix into a continuous phase. The as-prepared composite materials are used as supercapacitor electrodes in basic electrolyte. The Mn II Cr III 2 O 4 /Mn II Mn III 2 O 4 /C composite material possesses a high specific capacity of 184.0 mAh g −1 at a current density of 0.5 A g −1 with a superior rate capability of 138.3 mAh g −1 (75.2% retention) at 20 A g −1 . Meanwhile, CoCr 2 O 4 /C nanoparticles also deliver a high specific capacity of 158.8 mAh g −1 at a current density of 0.5 A g −1 with a superior rate capability of 125.0 mAh g −1 (78.7% retention) at 20 A g −1 . The good supercapacitive behaviors of the two composite materials are probably attributed to the characteristics of bimetallic compound and the presence of multiple valence states in the samples, giving rise to obvious redox responses. And the Mn II Cr III 2 O 4 /Mn II Mn III 2 O 4 /C and CoCr 2 O 4 /C composites possess reversible electrochromism .
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2022
·Vol. 15
·期 3
·793
·
IF 3.748
Hai Tang,Yuhao Zhou,Wenjie Yuan
To investigate the action mechanism of titanium, the effects of different Ti-bearing compounds, including CaTiO3, MgTiO3, and nano-TiO2, on the properties of alumina–magnesia castables were studied. By analyzing the phase compositions, microstructures, and physical and mechanical properties of the castables, it was demonstrated that an intermediate product, CaTiO3, was first generated. This was then consumed by solid-solution reactions, and titanium was involved in the liquid formation as the temperature increased. The solid-solution reaction of CA6(CaAl12O19) was more prominent due to the incorporation of more titanium in the crystal lattice of CA6instead of spinel (MgAl2O4). Moreover, the liquid formation was strongly promoted when more titanium accompanied the calcium, which finally accelerated the densification and improved the strengths of alumina–magnesia castables. On the whole, castables with CaTiO3addition presented higher bulk density and excellent strength after the heat treatment. Besides, the castables with 2 wt.% CaTiO3contents were estimated to possess greater thermal shock resistance.Keywords:Ti-bearing compounds;CA6;spinel;castables
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2024
·Vol. 55
·期 6
·4775-4786
·
IF 2.4
Luo Shuxuan,Ma Xingyue,Wang Wanlin,Zhang Lei,Sun Yongqi
The rapid advancement in stainless steel manufacturing has resulted in the substantial accumulation of stainless steel slags. In those slags, a significant proportion of trivalent chromium is susceptible to oxidation, forming highly toxic hexavalent chromium, particularly under oxidizing atmosphere. Therefore, prior to landfilling or resource recycling, specialized modification of phase transitions is essential. This study is based on the strategy of converting chromium into spinel structure to achieve detoxification. Initially, the thermodynamic calculations were conducted to analyze the formation and transformation behaviors of spinels in an alkaline environment, with particular emphasis on changes in the valence states of manganese. The synthesis and investigation of typical Mg 1− x Mn x Cr 2 O 4 spinels commonly encountered in stainless steel slags treatment process were subsequently conducted. Through various characterization techniques and leaching tests, it was found that the stability of Mn 2+ incorporated MgCr 2 O 4 was diminished. However, with an increase in MnO content from 5 to 20 pct (in mole), the stability of Mg 1− x Mn x Cr 2 O 4 spinels showed an upward trend, though remaining lower than that of pure MgCr 2 O 4 . The subsequent introduction of CaO for high-temperature calcination revealed that the disruption of tetrahedral sites in the spinels primarily originates from Mn 2+ , whereas Mg 2+ exhibited a greater stability in occupying tetrahedral sites. A comprehensive understanding of the properties of Mg 1− x Mn x Cr 2 O 4 spinels could contribute to the target modification and application of stainless steel slags.
研究领域:
材料科学
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环境工程
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化学工程
·
冶金学
✓ 已验证
DOI
高影响因子
BULLETIN OF THE CHEMICAL SOCIETY OF ETHIOPIA
·
2024
·Vol. 38
·期 5
·1429-1437
·
IF 1.3
Yu Sun,Chaofan Li,Hongcheng Gao,Jiaming Li,Jiabin Hao
A cubic spinel LiMn2O4 cathode material with nanoscale was synthesized via a facile liquid-combustion method at 600, 750 and 850 ℃. The crystal structure and surface morphology of LiMn2O4 electrodes have been characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technique. The samples have an average diameter of 200 nm with an octahedral structure with high crystallinity. Benefiting from the excellent structure, the sample prepared at 750 ℃ delivers the highest first discharge capacity of 115.3 mAh·g−1 with remaining 101.5 mAh·g−1 after 400 cycles at 1 C. Moreover, it exhibits a good cycling performance at 55 ℃, still had the capacity of 105.4 mAh·g−1 with a capacity retention of 71.2% following 282 cycles. The facilely synthesized octahedral LiMn2O4 provides a practical application strategy for lithium-ion batteries.
KEY WORDS: Spinel LiMn2O4, Liquid-combustion method, Lithium-ion batteries
Bull. Chem. Soc. Ethiop. 2024, 38(5), 1429-1437.
DOI: https://dx.doi.org/10.4314/bcse.v38i5.18
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE
·
2025
·Vol. 56
·期 3
·2541-2557
·
IF 3.1
Cao Jianqi,Feng Shanshan,Wang Wanlin,Huang Daoyuan,Sun Yongqi
Vanadium, an extremely important metal element, is dominantly produced from the roasting–leaching process of vanadium–bearing slags, with the roasting process involving a conversion of vanadium–containing phases including iron–vanadium spinels and liquid phase into soluble vanadate. It is difficult to extract vanadium from iron–vanadium spinels due to their ultrastabilities and complex compositions. The presence of minor elements affects the stability of iron–vanadium spinels upon roasting as well as the further leaching process. In this study, the roles of various minor elements on phase and composition evolutions of iron–vanadium spinels upon calcium roasting were investigated by both advanced experimental characterizations (EPMA, XRD and XPS) and thermodynamic calculation using FactSage 8.3. The results first showed that the iron–vanadium spinel underwent a phase transition to form two distinct phases, namely a V-enriched phase and a Fe 2 O 3 solid solution. The presence of Cr 2 O 3 , MnO and MgO did not produce a new phase, but affected the compositions of the two phases formed. However, new phases were generated in the presence of TiO 2 and Al 2 O 3 , namely a Fe 2 TiO 5 phase and an Al-enriched phase, respectively. Moreover, a higher roasting temperature enhanced the partitioning of TiO 2 , Al 2 O 3 and Cr 2 O 3 from the V-enriched phase to the Fe 2 O 3 solid solution, which promoted the enrichment of V 2 O 5 into the V-enriched phase. A lower roasting temperature promoted the formation of manganese vanadate and magnesium vanadate for further leaching process. These findings offer a guidance for optimizing the roasting conditions for maximum vanadium extraction from iron–vanadium spinels.
研究领域:
冶金学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Jianqi Cao,Lei Zhang,Wanlin Wang,Daoyuan Huang,Yongqi Sun
As a dominant resource for vanadium extraction, roasting of vanadium-bearing slags involves the destruction of vanadium-containing phases, mainly including iron-vanadium spinels and liquid phase, and the formation of soluble vanadate. Extraction of vanadium from iron-vanadium spinels determines the efficiency of the whole process due to their ultrastabilities. Here the phase and composition evolutions of iron-vanadium spinels containing chromium were investigated by both advanced experimental characterizations (EPMA, XRD and XPS, etc.) and thermodynamic analysis. The roles of roasting conditions were clarified, including roasting temperature, time and the presence of chromium. It was found that, upon roasting, the iron-vanadium spinels underwent a phase transition to form two distinct phases, namely a vanadium-enriched phase and a Me 2 O 3 solid solution phase. A relatively high roasting temperature with a relatively long roasting time could enhance the completeness of the roasting reaction and improve the separation of vanadium from iron and chromium. The evolution of iron-vanadium spinels with the current compositions (n(FeO): n(V 2 O 3 ): n(CaO): n(Cr 2 O 3 ) = 4: 1: 2: 0.2) followed a three-step mechanism under the current roasting conditions, i.e., an initial step of the oxidation decomposition of spinels, a reaction between CaO and V 2 O 5 to form CaV 2 O 6 , and a final reaction between residual CaO and CaV 2 O 6 to form a Ca 2 V 2 O 7 phase. Moreover, the presence of chromium resulted in an increase in the Fe 2 O 3 concentration within the vanadium-enriched phase due the formation of a solid solution with an infinite miscibility between Cr 2 O 3 and Fe 2 O 3 . The findings of this study offer not only scientific insight with regard to the evolution of iron-vanadium spinels upon roasting but also significant guidance for the optimization of roasting conditions toward target vanadium extraction from iron-vanadium spinels.
研究领域:
冶金学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2023
·Vol. 13
·期 5
·807
·
IF 3.9
Zhiping Zhao,Zhixia Wang,Yanbing Tong,Jinru Sun,Ming Ke,Weiyu Song
The search for inexpensive, environmentally friendly, and highly effective catalysts to activate C-H bonds in propane dehydrogenation (PDH) reactions is still a major challenge. Co-based catalysts have gained significant attention in recent years due to their excellent ability to activate C-H bonds and their high selectivity towards olefins, despite being a non-noble and environmentally unfriendly metal. However, further improvements are necessary for practical utilization, particularly in terms of activity and anti-carbon deposition capacity. In this study, we synthesized Al2O3nanorods with abundant pentacoordinated Al3+(Al3+penta) sites. The supported Co on the Al2O3nanorod (Co/Al2O3-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h−1) compared to Co supported on an Al2O3nanosheet with fewer pentacoordinated Al3+sites. Various characterizations confirmed that Co(II) mainly exists as CoAl2O4rather than Co3O4in the form of Co/Al2O3-NR, which inhibits the reduction of Co(II) to Co0and accordingly improves catalyst stability.Keywords:propane dehydrogenation;metal oxide;alumina;spinel
研究领域:
化学工程
·
催化材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Hang Liu,Shengqiang Song,Andrie M. Garbers-Craig,Zhengliang Xue
Cr 2 O 3 is a well-known corrosion resistant oxide used in refractory applications. However, it can oxidize into toxic and water-soluble Cr(VI) compounds upon reaction with calcium aluminate cement phases in the presence of oxygen, which subsequently causes disposal problems after use. This study describes the extent to which chromium in the spinel Mg(Al,Cr) 2 O 4 phase can be oxidized to Cr(VI) when it reacts with the calcium aluminate cement phases C 12 A 7 , CA, CA 2 and free CaO at 1300 °C in air, using XRD, XPS and leaching tests (TRGS 613 standard) as analytical tools. On reaction with CaO, the Mg(Al,Cr III ) 2 O 4 spinel mainly transformed into hauyne (Ca 4 Al 6 Cr VI O 16 ) and Ca 5 Cr 3 O 12 which contains both Cr(IV) and Cr(VI). The reaction of C 12 A 7 and CA with the spinel phase also resulted in the formation of Ca 4 Al 6 CrO 16 . Conversely, the reaction of Mg(Al,Cr III ) 2 O 4 spinel with CA 2 resulted in the formation of only a trace amount of Cr(VI). Water-soluble Cr(VI) leached in large quantities (>100 mg/L) from samples where the Mg(Al,Cr III ) 2 O 4 reacted with either C 12 A 7 or CA. Almost no Cr(VI) leached from the sample when Mg(Al,Cr III ) 2 O 4 reacted with CaO, using the standard TRGS 613 leach test, but a significant amount of Cr(VI) was released into solution when leached with a HCl solution for 12 h. Both Cr(IV) and Cr(VI) present in the Ca 5 Cr 3 O 12 dissolved into acidic solution. Only a small amount of Cr(VI) leached from the sample that resulted when spinel was reacted with CA 2 , even after a prolonged HCl leach. Cr(III) in spinel Mg(Al,Cr) 2 O 4 is very stable and does not leach in either distilled water or acidic solution.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Yihui Li,Ziang Zhao,Min Zhao,Hejun Zhu,Xinzheng Ma,Zheng Li,Wei Lu,Xingkun Chen,Linbin Ying,Ronghe Lin,Yu Meng,Yuan Lyu,Li Yan,Yunjie Ding
Promotional effects of oxygen vacancies of spinel catalysts in CO 2 hydrogenation are reported in early works, but the mechanistic origins remain elusive. Here, CoAl 2 O 4 spinels with varying numbers of oxygen vacancies are deliberately designed by a sol-gel method and different post-treatments. By combining catalytic testing, advanced electron microscopic and spectroscopic characterizations, and computational studies, the unusual oxygen vacancy-dependent catalytic behaviors are rationalized. Our work reveals that i) perfect spinel crystals possessing least oxygen vacancies can effectively constrain the Co 2+ species at working conditions that are less active but selective to CO; and ii) vacancy-rich spinels promote both H 2 and CO 2 activations and COOH* formation, explaining the higher hydrogenation activity, but overwhelming vacancies cause Co 2+ reduction and promote direct CO 2 * dissociation to CO* and deep hydrogenation to CH 4 . These molecular-level understandings reinforce the idea of proper design of oxygen vacancies to achieve activity-selectivity balance.
研究领域:
材料科学
·
催化化学
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yajie Wang,Ziyi Zhang,Jie Li,Ying Tang,Liang Fang
Excellent spinel microwave dielectric ceramics (1- x )Zn 2 TiO 4 - x Li 2 MgTi 3 O 8 (ZTLMT x , x = 1/3 and 2/3) were prepared at relatively low densification temperatures of 1100 °C and 1080 °C, respectively. A disordered cubic phase with space group Fd -3 m was formed at x = 1/3, whereas an ordered cubic phase with space group P 4 3 32 was formed at x = 2/3. The ceramics at x = 1/3 and 2/3 exhibited promising microwave dielectric properties of ɛ r = 18.27 and 22.96, Q × f = 91,877 GHz and 75,186 GHz, and τ f = −42.3 ppm/°C and −21.05 ppm/°C, respectively. The large deviation between the experimental ԑ r and theoretical ε th of 1/3 and 2/3 ceramics were 18.3 % and 57 %, respectively, due to the underestimation of the ionic polarizability of Ti 4+ . The difference in their ɛ r , Q × f , and τ f were discussed by the structure, FWHM of A 1g , lattice energy and bond energy in detail.
研究领域:
材料科学
·
陶瓷学
·
物理学
✓ 已验证
DOI
高影响因子
POWDER TECHNOLOGY
·
2020
·
IF 4.142
Zhenggen Liu,Lifeng Zhang,Mingyu Wang,Zichuan Zhao,Lihua Gao,Mansheng Chu
A new understanding of the reduction mechanisms of ferruginous manganese ores for ferromanganese alloy smelting was reported, and this new understanding was used to produce excellent ferromanganese alloys. To fulfill this objective, the effects of the operating variables on smelting ferromanganese alloys were initially investigated. The formation mechanisms and reduction reaction behaviors of olivine (Ca x Fe y Mn 2-x-y )SiO 4 , spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 , gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O systems were systematically discussed to understand the phase transformation and reconstruction of manganese ore at high temperatures. The spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 that originated from (Fe y Mn 1-y )Al 2 O 4 was converted to CaAl 2 O 4 and then further reduced to ferromanganese alloys. A similar expression was applied to describe how the reduction mechanism of olivine (Ca x Fe y Mn 2-x-y )SiO 4 that originated from (Fe y Mn 2-y )SiO 4 was converted to Ca 2 SiO 4 . In addition, the importance of the formation of gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O phases in smelting ferromanganese alloys was discussed and clarified in detail. Based on the findings, recommendations are provided for the theoretical basis and technical support of smelting ferromanganese alloys.
研究领域:
冶金学
·
材料科学
✓ 已验证
DOI
高影响因子
Materials
·
2021
·Vol. 14
·期 13
·3624
·
IF 3.623
Zhijie Xu,Fangxu Hu,De Li,Yong Chen
In the late 1960s, the establishment of Prigogine’s dissipative structure theory laid the foundation for the (electro)chemical oscillation phenomenon, which has been widely investigated in some electrochemical reactions, such as electro-catalysis and electro-deposition, while the electrochemical oscillation of Li-ion batteries has just been discovered in spinel Li4Ti5O12a few years before. In this work, spinel LiCrTiO4samples were synthesized by using a high-temperature solid-state method, characterized with SEM (Scanning electron microscope), XRD (X-ray diffraction), Raman and XPS (X-ray photoelectron spectroscopy) measurements, and electrochemically tested in Li-ion batteries to study the electrochemical oscillation. When sintering in a powder form at a temperature between 800 and 900 °C, we achieved the electrochemical oscillation of spinel LiCrTiO4during charging, and it is suppressed in the non-stoichiometric LiCrTiO4samples, especially for reducing the Li content or increasing the Cr content. Therefore, this work developed another two-phase material as the powder-sintered LiCrTiO4exhibiting the electrochemical oscillation in Li-ion batteries, which would inspire us to explore more two-phase electrode materials in Li-ion batteries, Na-ion batteries, etc.Keywords:Li-ion battery;LiCrTiO4;electrochemical oscillation;phase transition;spinel structure
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
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