Materials Today Communications
·
2025
·
IF 4.5
Zefeng Guo,Jianhua Zhang,Yongke Yan,Guoyu Zhang,Dongdong Liu,Zhipeng Lei,Yuanyuan Li,Lu Li
Achieving both low dielectric loss (tan δ ) and high temperature stability of ceramic capacitors can greatly broaden their potential application. In this study, the effects of Mg and Al co-substitution on the microstructure and dielectric properties of CCTO-based ceramics were investigated in CaCu 3- x Mg x Ti 4- x Al x O 12 ( x = 0, 0.025, 0.050, and 0.075) ceramics prepared by a sol-gel method. XRD analysis shows that the primary crystalline phase of CCTO is formed in all samples, indicating that Mg 2 + and Al 3+ have entered the lattice. SEM results reveal the co-substitution of Mg and Al inhibits the grain growth, leading to an increase in grain boundary density. All co-substituted samples exhibited low tan δ and excellent temperature stability. Notably, CaCu 2.95 Mg 0.05 Ti 3.95 Al 0.05 O 12 ceramics exhibited an extremely low tan δ of 0.007 (at 10 3 Hz) and its dielectric constant maintained excellent stability over a broad temperature spectrum (−125 to 150 °C), meeting the commercial standards for X8P capacitors. The reduction of tan δ is mainly attributed to the inhibition of grain growth in Mg and Al co-substituted samples, which increases grain boundary density and subsequently suppresses the mobility of oxygen vacancies, leading to an increase in grain boundary resistance. Furthermore, the improvement in temperature stability is ascribed to the reduction in the content of oxygen vacancies and the suppression of electron transitions between Ti 4+ and Ti 3+ as well as Cu 2+ and Cu + in Mg and Al co-substituted samples, resulting in an increase in grain boundary activation energy. These novel findings are hoping to contribute to not only the fabrication of new CCTO-based ceramics with extremely low tanδ and excellent temperature stability but also the application of CCTO-based ceramics at a very broad temperature range in electronic devices, new energy vehicles, aerospace, and polar scientific research equipment.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
POWDER METALLURGY AND METAL CERAMICS
·
2021
·Vol. 59
·期 11
·651-660
·
IF 0.511
Zhangjun Bai,Yuhong Chen,Lu Li,Jiaxin Li,Yuewei Cheng
In this study, Ta–W–Ti–Al multialloys were prepared by spark plasma sintering (SPS) as a new powder metallurgy technology based on discharge activation and thermoplastic deformation process. The oxidation behavior of the as-obtained sintered alloys were investigated under 1000 and 1200°C in air atmosphere. Microstructures and phase compositions of alloys and oxides were analyzed using various analytical methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and backscatter electron microscopy (BSE). The sintered samples possessed relative densities reaching up to 98% with achievable densification. The densities of all specimens with high Ti contents exceeded 100%, suggesting the great impact of Ti addition on liquid-phase precipitation. Intermetallic compounds were formed in Ta–W–Al alloys, and samples with high Ti contents displayed grain boundary phases rich in titanium and oxygen. The addition of Ti and Al effectively improved the oxidation resistance of the resulting alloys. A protective alumina layer was formed after oxidation at 1000°C that made oxidation kinetics of the alloys obeying pseudo-parabolic laws. At the oxidation temperature of 1200°C, Al 2 O 3 reacted with Ta 2 O 5 to form the AlTaO 4 alloy with reduced protective effect. The mass gain in the alloys after oxidation at 1200°C for 4 h was about 7 times higher compared to processing at 1000°C.
研究领域:
材料科学
·
冶金工程
✓ 已验证
DOI
高影响因子
Russian Journal of Physical Chemistry A
·
2023
·Vol. 97
·期 13
·2966-2975
·
IF 0.7
Liu Kun,Zhu TianHan,Li Feng,Wang Jing,Song Hua
A series of Ni/SiO 2 –Al- x catalysts ( x is the initial mass ratio of SiO 2 to Al(NO 3 ) 3 ) with different aluminum contents was prepared by impregnation method using nickel nitrate as the Ni source. The prepared Ni/SiO 2 –Al- x catalysts were characterized by XRD, BET, TPR, TEM, XPS, NH 3 -TPD, and Py-FTIR methods. Taking m -cresol as a model compound, the effects of aluminum content and reaction conditions on the HDO performance were investigated. Results showed that addition of appropriate amount of aluminum can generate acid sites and improve the metal Ni dispersion by increasing the surface area of catalyst. Furthermore, the selectivity to deoxygenated methyl-cyclohexane product over aluminum modified Ni/SiO 2 –Al- x catalysts increased significantly as compared to that of Ni/SiO 2 , which confirmed the importance of aluminum addition on the dehydration of 3-methyl-cyclohexanol to methyl-cyclohexane. Among the prepared Ni/SiO 2 –Al- x catalysts, the Ni/SiO 2 –Al-5 catalyst exhibits the best HDO performance. A 100% m -cresol conversion with the selectivity to MCH of 100% was achieved under the conditions of T = 250°C, p = 2 MPa, t = 75 min with catalyst (mg)/ m -cresol solution = 2.
研究领域:
催化化学
·
能源化学
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材料化学
·
工业催化
·
绿色化学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Yiwei Sun,Xiaoli Wei,Fangcao Liu,Bing Liu,Jiaming Zhao,Yubao Bi,Wenfeng Han
Developing effective techniques to produce and stabilize highly active metastable F-Al-O species in HFCs dehydrofluorination system without being over-fluorinated to Al-F is a major challenge. Herein, we report a new strategy for the formation and stabilization of metastable species. Using NaH 2 PO 4 as a P source, phosphoric acid groups are modified to the surface of Al 2 O 3 leading to the fabrication of AlPO 4 /Al 2 O 3 interface. P and Al 2 O 3 bond to form Al-O-P structure at the interface and stabilize F-Al-O in the dehydrofluorination system. Further studies show that AlPO 4 /Al 2 O 3 interface increase the oxygen vacancy content of catalyst and accelerate the conversion of HFC-152a on the catalyst surface. Meanwhile, AlPO 4 /Al 2 O 3 interface improves the surface acidity of Al 2 O 3 , endue a large number of Lewis weak acid sites, reducing the carbon accumulation of catalyst, and improving the stability of catalyst. The activity test showed that AlPO 4 /Al 2 O 3 interface shows high catalytic performance (74.2 %) and excellent stability (50 h) for 1,1-difluoroethane dehydrogenation compared with Al 2 O 3 (30 % and low stability) without P modification.
研究领域:
化学工程
·
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Nano Materials
·
2021
·
IF 5.097
Muhammad Amin Padhiar,Minqiang Wang,Yongqiang Ji,Zhi Yang,Yun Zhou,Hengwei Qiu,Hao Wang,Azaz Ali Shah,Arshad Saleem Bhatti
Perovskite nanocrystals (PNCs) are ideal for optical devices due to their adjustable emission band and high photoluminescence. However, blue light-emitting perovskite nanocrystals (PNCs) exhibit poor performance compared to their green and red-emitting PNC counterparts. Herein, we introduce a simple strategy for increasing the stability of blue light-emitting CsPb (Br/Cl)3 PNCs passivated with an Al-doped CdSe layer. This simple strategy successfully achieves highly stable PNCs with photoluminescence (PL) emission ranging from 454 to 460 nm with a full width at half-maximum (FWHM) ranging from 18 to 22 nm; changes in bandgaps are also observed, and the corresponding PLQY values show a significant change after CdSe/Al modification. In addition, CsPb (Br/Cl)3 PNCs with a CdSe layer doped with Al formed on the surface show remarkable stability under ambient conditions, including thermal exposure, water resistance, and ultraviolet (UV) irradiation. A light-emitting diode (LED) device was constructed to demonstrate the feasibility of the approach by combining the optimal CsPb(Br/Cl)3/CdSe/Al PNCs with an existing commercial 365 nm UV chip, resulting in bright blue light emission with CIE color coordinates of (0.16, 0.09). All of the findings suggest that doped CsPb (Br/Cl)3/CdSe/Al PNCs have the potential to be used as color converters in liquid crystal displays (LCDs).
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2014
·Vol. 4
·期 4
·1028-1037
·
IF 4.76
Haiping Li,Quanhua Deng,Jingyi Liu,Wanguo Hou,Na Du,Renjie Zhang,Xutang Tao
Bi2MoO6/Zn–Al layered double hydroxide (LDH) hierarchical heterostructures assembled from Bi2MoO6 hierarchical hollow spheres and Zn–Al LDH nanosheets were synthesized by a low-temperature hydrothermal method. X-ray diffraction, Fourier transform-infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS) confirmed the formation of the Bi2MoO6/Zn–Al LDH composites. Morphologies were characterized by scanning electron microscopy and transmission electron microscopy (TEM). XPS and high resolution TEM indicated the formation of a Bi2MoO6/Zn–Al LDH heterojunction. Increasing the LDH content from 0 to 27.0 wt.% caused the Brunauer–Emmett–Teller (BET) specific surface area of the composites to gradually increase. The photocatalytic degradation activity for Rhodamine B (RhB) under visible light irradiation exhibited a large enhancement, followed by a decrease, with increasing LDH content. The Bi2MoO6/Zn–Al LDH heterostructure composite with LDH content of 5.5 wt.% showed the highest photocatalytic activity and degraded 99% of RhB in 80 min, while Bi2MoO6 degraded less than 50%. The average photocatalytic efficiency is enhanced by more than 100%. The enhanced photocatalytic activity of the Bi2MoO6/Zn–Al LDH heterostructure photocatalyst was mainly attributed to the efficient separation of photoinduced electrons and holes. Superoxide radicals and holes were the major active species. The Bi2MoO6/Zn–Al LDH heterostructure photocatalyst exhibited excellent stability and reusability. A detailed mechanism for its enhanced photocatalytic activity was discussed in this study. This work provides an effective way to fabricate a series of Bi-based and LDH-containing heterostructure photocatalysts.
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
BMC Chemistry
·
2024
·Vol. 18
·期 1
·1-13
·
IF 4.3
Chen Jialin,Li Shutao,Dai Mengnan,An Ming,Song Rui,Chen Yeqing,Song Jiaxing,Tian Quanwei,Zhong Xiting,Yan Qiushi
To improve the thermal and combustion properties of nanothermites, a design theory of changing the state of matter and structural state of the reactants during reaction was proposed. The Al/MoO 3 /KClO 4 (Kp) nanothermite was prepared and the Al/MoO 3 nanothermite was used as a control. SEM and XRD were used to characterize the nanothermites; DSC was used to test thermal properties; and constant volume and open combustion tests were performed to examine their combustion performance. Phase and morphology characterization of the combustion products were performed to reveal the mechanism of the aluminothermic reaction. The results show that the Al/MoO 3 /Kp nanothermite exhibited excellent thermal properties, with a total heat release of 1976 J·g − 1 , increasing by approximately 33% of 1486 J·g − 1 of the Al/MoO 3 nanothermite, and activation energy of 269.66 kJ·mol − 1 , which demonstrated higher stability than the Al/MoO 3 nanothermite (205.64 kJ·mol − 1 ). During the combustion test, the peak pressure of the Al/MoO 3 /Kp nanothermite was 0.751 MPa, and the average pressure rise rate was 25.03 MPa·s − 1 , much higher than 0.188 MPa and 6.27 MPa·s − 1 of the Al/MoO 3 nanothermite. The combustion products of Al/MoO 3 nanothermite were Al 2 O 3 , MoO, and Mo, indicating insufficient combustion and incomplete reaction, whereas, the combustion products of Al/MoO 3 /Kp nanothermite were Al 2 O 3 , MoO, and KCl, indicating complete reaction. Their “coral-like” morphology was the effect of reactants solidifying after melting during the combustion process. The characterization of reactants and pressure test during combustion reveals the three stages of aluminothermic reaction in thermites. The excellent thermal and combustion performance of Al/MoO 3 /Kp nanothermite is attributed to the melt and decomposition of Kp into O 2 in the third stage. This study provides new ideas and guidance for the design of high-performance nanothermites.
研究领域:
材料科学
·
燃烧学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Lina Sun,Ping Ning,Jie Yang,Xin Song,Kai Li
This study used metal oxide-modified metal-organic frameworks to examine H 2 S catalytic oxidation selectivity. The findings revealed that the oxidation mechanisms and products differed between Fe 2 O 3 /UiO-66 and Al 2 O 3 /UiO-66. The dithionates were intermediate products of H 2 S oxidation on Al 2 O 3 /UiO-66, whereas the bisulfates were intermediate products on Fe 2 O 3 /UiO-66. Fe 2 O 3 /UiO-66 showed stronger surface oxidation activity than Al 2 O 3 /UiO-66. The formation of sulfate/SO 2 was primarily attributable to surface oxygen, whereas elemental sulfur was primarily related to lattice oxygen. The product generation processes of H 2 S on Fe 2 O 3 /UiO-66 and Al 2 O 3 /UiO-66 surfaces were as follows: H 2 S → HSO 4 2− → SO 2 → S for Fe 2 O 3 /UiO-66, while H 2 S → S 2 O 4 2− → SO 2 for Al 2 O 3 /UiO-66. H 2 O and surface oxygen have the potential to alter H 2 S adsorption on the catalyst surface. For Fe 2 O 3 , the conversion of H 2 S to SO 2 involves both an oxidation process and a reduction process. For Al 2 O 3 , the conversion of H 2 S to SO 2 includes two oxidation processes. Due to the oxidation step of S 2 O 4 2− limiting the generation of SO 2 , the reduction process of SO 2 was also hindered, which in turn restricted the production of S over Al 2 O 3 . Fe 2 O 3 can achieve the oxidation and removal of H 2 S at lower reaction temperatures, while also creating elemental S.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
·
2015
·Vol. 2015
·期 12
·2125-2131
·
IF 2.942
Chunyan Sun,Feng Zhang,Xiao Wang,Fangqin Cheng
Graphical A composite ammonium molybdophosphate/Al-MCM-41 material is synthesized by a one-pot method with natural clay as the silica and aluminum source. A modified “liquid-phase transport” step allows the use of impure natural clay as the starting material to produce pure product without sedimentation pretreatment. The composite material is effective for the adsorption of cesium ions from brine. Ordered hexagonal mesoporous aluminosilicate matrix (Al-MCM-41) with incorporated ammonium molybdophosphate (AMP) was successfully synthesized by a one-pot synthesis method with natural clay from low-grade potash ores of Qinghai salt lake as the silica and aluminum source. We introduced a modified “liquid-phase transport” step, which allowed the use of impure natural clay as a starting material to directly produce pure product without sedimentation pretreatment. The resultant product was characterized by X-ray fluorescence (XRF) spectroscopy, FTIR spectroscopy, XRD, TEM, 27 Al and 31 P magic-angle spinning (MAS) NMR spectroscopy, and N 2 adsorption/desorption, which indicated that the AMP was immobilized in the mesoporous structure of Al-MCM-41. The adsorption capacity of the final product for the removal of cesium ions in solution was also investigated. The results suggested that salt lake clay is a promising low-cost precursor for the production of mesoporous aluminosilicate supports through one-pot syntheses, and the final composite material is effective for the adsorption of cesium ions from solutions containing other alkali metal ions.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Cong Xie,Xiao Zhang,Wenbin Shi,Ping Yang
The poor stability of perovskite nanomaterials exposed in high temperature, moisture, light radiation, and polar solvent conditions severely restrict their commercial application. To address this issue, the growth in situ of CsPbX 3 (X = Cl, Br, I) nanocrystals (NCs) is carried out by using the stable aluminum (Al)-based metal-organic frameworks to create CsPbX 3 @MIL-53(Al) composites. Compared with pristine CsPbX 3 NCs prepared using room temperature ligand assisted re-precipitation synthesis, the CsPbX 3 @MIL-53(Al) composites exhibit narrow photoluminescence (PL) spectra and greatly improved stability. The green emitting CsPbBr 3 @MIL-53(Al) composite exhibit narrowed PL spectrum (the full width at half-maximum of PL spectra: 20 nm for the composite and 28 nm for CsPbBr 3 NCs) and a blue-shifted PL peak wavelength (517.6 nm for the composite and 527.6 nm for the CsPbBr 3 NCs). The relationship of microstructure, components, PL, fluorescence lifetime, and stability are discussed systematically. Anomalous stability against heat-treatment, polar solvent and humidity conditions indicated the composites retained their initial PL intensity after storge more than 4 months in ambient conditions and heat-treated to 120ºC for 5 cycles. The emitting color of CsPbBr 3 @MIL-53(Al) composites are easily adjusted from blue, green to red by controlling the halide components of precursors. The composite was used to create emitting coating and highly bright flexible emitting films which also reveal high stability, suggesting that in situ encapsulation of CsPbX 3 NCs in MIL-53(Al) would supply a novel platform for various emitting devices.
研究领域:
材料科学
·
纳米技术
·
光电技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
·
2020
·Vol. 29
·期 2
·1375-1383
·
IF 1.652
Yin Yanjun,Li Xueming
In this work, an Al/CuO energetic film with a porous hollow structure was obtained by electrophoretic deposition (EPD) from an aqueous solution at low field strengths of 20 V cm −2 instead of from organic solvents. CuO porous hollow microspheres (PHMSs) were prepared by a one-step hydrothermal method. The shape of the CuO PHMSs was very uniform at the macroscale with a size of 5 μm. To codeposit the species during the EPD process, the nano-Al particles and CuO PHMSs were modified with acrylic acid and citric acid, respectively. The nano-Al particles were deposited on the surface or in the interior of the CuO PHMSs by an electrical field and formed Al/CuO PHMS composites. The chemical composition, morphology, heat release and combustion of the as-prepared composite coating films were analyzed by XRD, FESEM, FT-IR, EDS, TG-DSC and with a high-speed camera. The heat release of the Al/CuO porous thermite reached 3804 J/g with excellent combustion performance due to the novel microstructure and appropriate modifications.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Jianrong Shan,Bowen Yang,Yaqiong Su,Gunhean Chong,Luqman Chuah Abdullah,Xinhua Qi,Haixin Guo
Isomerization of glucose to fructose is a key step in achieving high value conversion of biomass. Lignin nanosphere (LN) showing hollow structure were successfully prepared using lignin oligomers as carbon precursors and self-assembly method. On this basis, Mg and Al were doped into lignin nanospheres by electrostatic and coordination interactions to obtain a heterogeneous catalyst (Mg x Al y /LN) with the coexistence of Brønsted base and Lewis acid. In this catalytic system, the synergistic effect of Al(OH) 3 and MgO as the active center of the catalyst promoted the formation of intermediates for the isomerization of glucose to fructose. DFT analysis show that Al(OH) 3 plays a greater role than MgO in promoting the isomerization of acyclic glucose to form fructose. When the Mg/Al ratio of 2:1, the yield of Mg 2 Al 1 /LN catalyzed isomerization of glucose to fructose under microwave irradiation can reach as high as 57.2 %, which could be reused for 5 times and still remain its initial activity. The activation energy was about 39.8 kJ/mol, which was lower than that of most heterogenous catalytic systems, showing good catalytic performance and potential for application.
研究领域:
催化化学
·
生物质转化
·
纳米材料
·
绿色化学
✓ 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）