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Lightweight,self-cleaning and refractory FeCo@MoS_(2)PVA aerogels:from electromagnetic wave-assisted synthesis to flexible electromagnetic wave absorption

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Rare Metals 2023年第4期42卷 1294-1305页

作者： Sai-Bo Qian Guang Liu mi yan Chen Wu School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhou310027China

The emergence of wearable and foldable electronic devices urges advanced electromagnetic(EM)wave absorbers with maintained performance under *** FeCo@MoS_(2)poly vinyl alcohol(PVA)aerogels have been fabricated with the assistance of EM waves for simultaneous splitting of the MoS_(2)flakes and dispersive growth of FeCo *** resultants in-return have been used for EM wave absorption with excellent performance,providing minimum reflection loss(RL_(min))of-40.7 dB and a broad effective absorption bandwidth(EAB)of 6.4 GHz at a thickness of 2.5 ***-time compression has been introduced to reveal the evolution of EM *** aerogels maintain satisfactory performance even under 50%compression due to the balance of impedance matching and *** the deterioration of impedance matching,the attenuation is significantly enhanced due to both strengthened conductive loss and magnetic *** addition,features such as lightweight,self-cleaning and refractory can be achieved for the aerogels for applications in complex *** such this work not only provides a versatile synthetic route assisted by EM wave energy,but also insights on the evolution of absorption performance under deformation together with the design strategy of multifunctional flexible wave absorbers.

关键词： Electromagnetic(EM)wave assistance Multifunctional aerogels Deformative wave absorption Impedance matching Conductive loss Magnetic loss

Reduction of Sensitivity to Sintering Temperature for Nd-Fe-B Magnets through Zr and Nb Additions

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Journal of Materials Science & Technology 2009年第5期25卷 629-632页

作者： mi yan Xigui Cui Lianqing Yu Tianyu Ma State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China

To reduce the sensitivity of grain growth to sintering temperature for improving property consistency of sintered Nd-Fe-B magnets, combined additions of Zr and Nb were investigated. It was found that when Zr content was increased to 0.07 at. pct, abnormal grain growth was effectively hindered even when the sintering temperature reached 1100℃. With combined additions of 0.07 at. pct Zr and 0.07 at. pct Nb, the sensitivity of grain growth to sintering temperature was greatly reduced consistency than the magnets containing no Zr and also improved. The magnets sintered at 1100℃ showed higher property Nb. In addition, the magnetic properties of magnets were also improved.

关键词： Sintered Nd-Fe-B magnet Magnetic properties Consistency Sintering temperature

Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets

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Chinese Physics B 2019年第7期28卷 25-53页

作者： mi yan Jiaying Jin Tianyu Ma School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsKey Laboratory of Novel Materials for Information Technology of Zhejiang Province Zhejiang University

Since the 1980 s, Nd–Fe–B with largest energy product(BH)max approaching the theoretical limit has become the landmark of permanent magnetic *** application spectrum for Nd–Fe–B continues to expand over time both in the industrial and commercial sectors, which leads to growing research interests for solving the long-standing drawbacks of Nd–Fe–B, i.e., poor corrosion resistance, low coercivity, high Dy/Tb and low La/Ce/Y *** the above obstacles, we aim to present the novel grain boundary restructuring(GBR) approach, from GB design, processing, to structure evolution and property evaluation with a focus on the corrosion and coercivity mechanism of the restructured 2:14:1-typed *** with an introduction to the fundamental of GBR, two representative examples,high-electrode-potential(Pr, Nd)32.5Fe62.0Cu5.5 and low-melting-point Dy71.5Fe28.5, are given with detailed descriptions of the advantages of GBR to enhance the intrinsic anti-corrosion stability and to strengthen the coercivity at low Dy ***–property correlations are established to understand the critical importance of regulating the restructured GB phase to maximize the all-round performance of the 2:14:1-typed permanent *** at sustainable and balanced development of rare earth(RE) industry, the proceeding section proposes new prototypes of La–Ce and Y–Ce co-substitutions with dual benefits of stabilizing the 2:14:1 tetragonal phase and strengthening the intrinsic hard *** findings of additional REFe2 intergranular phase delight that the GBR approach also opens up a new horizon of research and application to develop high-performance La/Ce/Y-rich permanent magnets with deliberately tailored GB phase.

关键词： grain boundary restructuring coercivity corrosion resistance Dy/Tb La/Ce/Y

Recent advances in 2D semiconductor nanomaterials for photocatalytic CO_(2)reduction

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Nano Research 2023年第7期16卷 8542-8569页

作者： Tong Li Hongwei Huang Shuobo Wang yan mi Yihe Zhang Beijing Key Laboratory of Materials Utilization of Nonmetallic minerals and Solid Wastes National Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of Geosciences(Beijing)Beijing 100083China Goods and Material Department of CASIC Tertiary Research Institute China Aerospace Science and Industrial CorporationBeijing 100074China Key Laboratory of Chemistry and Engineering of Forest Products State Ethnic Affairs CommissionGuangxi Key Laboratory of Chemistry and Engineering of Forest ProductsGuangxi Collaborative Innovation Center for Chemistry and Engineering of Forest ProductsGuangxi Minzu UniversityNanning 530006China

For decades,global warming and energy shortages have been two urgent problems in human *** solar-driven photocatalytic conversion of carbon dioxide(CO_(2))into hydrocarbon fuels is expected to become a technology to solve these ***-dimensional(2D)materials shine in the field of photocatalytic CO_(2)due to their layered structure,larger specific surface area,more active sites,and larger charge transfer *** article reviews the progress of CO_(2)reduction by several types of 2D materials in recent ***,the reduction of CO_(2)is difficult in terms of kinetics and thermodynamics,but it is found through theoretical calculations and experiments that 2D materials have certain advantages in the reduction of CO_(2).Then the preparation methods of 2D materials are summarized and a variety of 2D materials are discussed and ***,an outlook on the development trend of 2D materials is *** review aims to provide systematic and concise guidance for the design of 2D nanomaterials for photocatalytic CO_(2)reduction.

关键词： two-dimensional(2D)materials photocatalysis CO_(2)reduction charge separation reactive sites

Extra-wide bandwidth via complementary exchange resonance and dielectric polarization of sandwiched FeNi@SnO_(2)nanosheets for electromagnetic wave absorption

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Journal of Materials Science & Technology 2021年第31期90卷 1-8页

作者： Huipeng Lv Chen Wu Faxiang Qin Huaxin Peng mi yan School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhou310027China

Advanced electromagnetic(EM)wave absorbers with wide bandwidth is crucial to avoid EM interference and radiation,while achieving compensatio nal attenuation at different frequencies is challe ***,two-dimensional(2 D)sandwiched FeNi@SnO_(2)have been designed,for which SnO_(2)nanosheets provide numerous heterogeneous nucleation sites for the growth of dispersive FeNi nanoparticles with reduced *** SnO_(2)exhibits dipole polarization at 21.45 GHz with a width of~4.00 GHz,while the FeNi nanoparticles induce excha nge resonance at 18.13 GHz(~6.00 GHz width)and interfacial polarization at15.97 GHz(~6.00 GHz width).Such complementary attenuation mechanisms give rise to an impressive ultra-wide effective absorption bandwidth of 11.70 GHz with strong absorption of-49.1 dB at a small thickness of 1.75 *** only superior EM wave absorption is achieved in this work,it also provides a versatile strategy to integrate different loss mechanisms in the design of EM wave absorbers with extra-wide bandwidth.

关键词： Sandwiched FeNi@SnO_(2)nanosheets Dielectric polarization Exchange resonance Complementary attenuation Electromagnetic wave absorption

Sodium Nitrate Passivation as a Novel Insulation Technology for Soft Magnetic Composites

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Engineering 2023年第1期20卷 134-142页

作者： mi yan Qiming Chen Dong Liu Chen Wu Jian Wang State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China School of Chemical Engineering Shandong University of TechnologyZibo 255049China National Institute for Materials Science Tsukuba 305-0047Japan

Sodium nitrate passivation has been developed as a new insulation technology for the production of FeSiAl soft magnetic composites (SMCs). In this work, the evolution of coating layers grown at different pH values is investigated involving analyses on their composition and microstructure. An insulation coating obtained using an acidic NaNO_(3) solution is found to contain Fe2O_(3), SiO_(2), Al2O_(3), and AlO(OH). The Fe2O_(3) transforms into Fe3O4 with weakened oxidizability of the NO_(3)– at an elevated pH, whereas an alkaline NaNO_(3) solution leads to the production of Al2O_(3), AlO(OH), and SiO_(2). Such growth is explained from both thermodynamic and kinetic perspectives and is correlated to the soft magnetic properties of the FeSiAl SMCs. Under tuned passivation conditions, optimal performance with an effective permeability of 97.2 and a core loss of 296.4 mW∙cm−3 is achieved at 50 kHz and 100 mT.

关键词： Soft magnetic composites Surface passivation Insulation technology Growth mechanism Magnetic performance

PCDD/Fs in soil around a hospital waste incinerator:comparison after three years of operation

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Journal of Environmental Sciences 2012年第4期24卷 699-703页

作者： Xiaodong Li mi yan Jie yang Tong Chen Shengyong Lu Jianhua yan State Key Laboratory of Clean Energy Utilization Zhefiang UniversityHangzhou 310027China

Polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDD/Fs） can be formed during the cooling of flue gases in waste incinerator. These pollutants are either in the gas phase or attached to the fine particles, escaping dust collection. After stack emission, they are slowly oxidized photochemically （gas phase）, or eventually are deposited （dry and wet deposition of particulate） in earth surface. In 2007 and 2010, 11 soil samples were collected in the vicinity of a hospital waste incinerator （HWI）, prior and after its startup. In order to find out any variation of PCDD/Fs in soil, in brief dioxins, their concentrations were analyzed by high-resolution gas chromatography with high-resolution mass spectrometry （HRGC/HRMS）. Compared to the baseline survey （2007）, PCDD/Fs in soil significantly increased, by average, ＋81.6% in total PCDD/Fs and ＋132.7% in international toxic equivalency （I-TEQ） unit. By principal component analysis （PCA）, both the PCDD/Fs homologue and the HxCDF isomer profile in soil were found to become more similar with fly ash. Generally, this incinerator influences the soil only in a limited area. More comprehensive supervision, stricter management and more advanced technology should be implemented in this plant to reduce pollutants emission, even though the level of PCDD/Fs in soil is quite low at present.

关键词： soil dioxin variation waste incinerator

Unraveling the evolution of oxygen vacancies in TiO_(2–x)/Cu and its role in CO_(2)hydrogenation

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Science China Chemistry 2024年第12期67卷 4125-4133页

作者： Ke Wang Fanxing Zhang Ning Cao Ying Bao mi yan Keping yan Pengfei Xie College of Chemical and Biological Engineering Zhejiang UniversityHangzhou 310058China Institute of Zhejiang University-Quzhou Quzhou 324000China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310058China State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization Baotou Research Institute of Rare EarthsBaotou 014030China Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering Taiyuan 030032China Department of Chemistry Western Washington UniversityBellinghamWA 98225USA

The remarkable contribution of oxygen vacancies has been revealed by the operando spectroscopies for methanol synthesis from CO_(2)hydrogeneration on the reducible metal oxide-supported copper ***,a challenge remains in the intrinsic understanding of the evolution and advantage of oxygen vacancies for methanol *** we prepare the TiO_(2–x)/Cu with different oxygen vacancy densities by adjusting the ball-milling *** the optimal condition,a TiO_(2–x)/Cu with more oxygen vacancies delivers an excellent methanol yield of 26.5 mmol g^(-1)h^(-1)at 300℃with a selectivity of more than 70%.The combined analysis of experimental characterizations and theoretical calculations reveals that the mutual dispersions of TiO_(2–x)and Cu driven by mechanical energy induce the electron rearrangement in the d orbital of the Ti atom and relax the Ti–O binding at the interface,which facilitates the formation of oxygen vacancies that further reduce the barrier of CO_(2)hydrogenation to^(*)HCOO due to higher nucleophilicity of titanium ions.

关键词： methanol synthesis TiO_(2-x)/Cu oxygen vacancies interfacial dynamics

Enhanced Magnetostriction of a Narrow Hysteresis Tb_(0.26)Dy_(0.54)Ho_(0.20)Fe_2 Alloy

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Acta Metallurgica Sinica(English Letters) 2013年第4期26卷 461-466页

作者： Xingwen PAN Changsheng ZHANG Tianyu MA mi yan Jing LI State Key Laboratory of Silicon Materials Department of Materials Science and EngineeringCyrus Tang Center for Sensor Materials and ApplicationsZhejiang University

In this work, a magnetic annealing method used to enhance the magnetostrictive property of a narrow hysteresis alloy ***0.20Fe2 is reported. Cylindrical-rod shaped specimen with 〈110〉 crystal orientation was fabricated using zone-melting unidirectional solidification technique, followed by annealing in a transverse magnetic field of 366 kA/m. The crystal orientation and bi-phase solidified morphology can be retained after magnetic annealing. A high magnetostriction of 1.508×10^-3 was obtained in the magnetically annealed specimen, which is 25.2% larger than the untreated one. Simultaneously, the magnetostriction hysteresis width is slightly enlarged from 4.45 to 6.36 kA/m, which is still much lower than that of the Ho-free ***2 alloy. The additional anisotropy which is induced by magnetic annealing, as reflected by the magnetic hysteresis loops, is responsible for the enhancement of magnetostrictive performance.

关键词： Magnetostriction Magnetostriction hysteresis Induced anisotropy