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Recent progress in the development of RE_(2)TMTM’O_(6)double perovskite oxides for cryogenic magnetic refrigeration

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Journal of Materials Science & Technology 2023年第5期136卷 1-12页

作者： Lingwei Li mi yan Key Laboratory of Novel Materials for Sensor of Zhejiang Province Institute of Advanced Magnetic MaterialsHangzhou Dianzi UniversityHangzhou 310012China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China

The magnetic functional materials play a particularly important role in our modern society and daily life.The magnetocaloric effect(MCE)is at the basis of a solid state magnetic refrigeration(MR)technology which may enhance the efficiency of cooling systems,both for room temperature and cryogenic appli-cations.Despite numerous experimental and theoretical MCE studies,commercial MR systems are still at developing stage.Designing magnetic solids with outstanding magnetocaloric performances remains therefore a most urgent task.Herein,recent progresses on characterizing the crystal structure,magnetic properties and cryogenic MCE of rare earths(RE)-based RE_(2)TMTM’O_(6)double perovskite(DP)oxides,where TM and TM’are different 3d transition metals,are summarized.Some Gd-based DP oxides are found to exhibit promising cryogenic magnetocaloric performances which make them attractive for active MR ap-plications.

关键词： Magnetocaloric effect(MCE) Rare earths Double perovskite(DP)oxides Magnetic functional materials Cryogenic magnetic refrigeration Magnetocaloric performances

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 deformation.Here 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 nanoparticles.The 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 mm.Real-time compression has been introduced to reveal the evolution of EM parameters.The aerogels maintain satisfactory performance even under 50%compression due to the balance of impedance matching and attenuation.Despite the deterioration of impedance matching,the attenuation is significantly enhanced due to both strengthened conductive loss and magnetic loss.In addition,features such as lightweight,self-cleaning and refractory can be achieved for the aerogels for applications in complex environments.As 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

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

Machine Learning-Assisted High-Throughput Virtual Screening for On-Demand Customization of Advanced Energetic Materials

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Engineering 2022年第3期8卷 99-109页

作者： Siwei Song Yi Wang Fang Chen mi yan Qinghua Zhang Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900China

Finding energetic materials with tailored properties is always a significant challenge due to low research efficiency in trial and error.Herein,a methodology combining domain knowledge,a machine learning algorithm,and experiments is presented for accelerating the discovery of novel energetic materials.A high-throughput virtual screening(HTVS)system integrating on-demand molecular generation and machine learning models covering the prediction of molecular properties and crystal packing mode scoring is established.With the proposed HTVS system,candidate molecules with promising properties and a desirable crystal packing mode are rapidly targeted from the generated molecular space containing 25112 molecules.Furthermore,a study of the crystal structure and properties shows that the good comprehensive performances of the target molecule are in agreement with the predicted results,thus verifying the effectiveness of the proposed methodology.This work demonstrates a new research paradigm for discovering novel energetic materials and can be extended to other organic materials without manifest obstacles.

关键词： Energetic materials Machine learning High-throughput virtual screening Molecular properties Synthesis

Concurrent improvements of corrosion resistance and coercivity in Nd-Ce-Fe-B sintered magnets through engineering the intergranular phase

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Journal of Materials Science & Technology 2022年第15期110卷 239-245页

作者： Jiaying Jin Yongming Tao Xinhua Wang Zeyu Qian Wang Chen Chen Wu mi yan School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsKey Laboratory of Novel Materials for Information Technology of Zhejiang ProvinceZhejiang UniversityHangzhou 310027China

Usually the improved coercivity of rare earth(RE)based 2:14:1-type permanent magnets via RE-rich intergranular additives is achieved at the cost of more corrosion channels and deteriorated corrosion resistance,which remains a challenging hurdle in the RE-Fe-B community.Distinctly,here we report the concurrent improvements of corrosion resistance and coercivity in 40 wt.%Ce-substituted Nd-Ce-Fe-B sintered magnets through engineering the intergranular phase using simple(Nd,Pr)H_(x)additive.The dehydrogenated Nd/Pr changes the RE concentration gradients between 2:14:1 matrix and intergranular phases during sintering and enlarges the fraction of corrosion-resistant REFe_(2) phase,rather than the conventionally assumed Nd/Pr-rich intergranular phase with high chemical vulnerability.The spontaneous formation of REFe_(2) intergranular phase after(Nd,Pr)H_(x) addition generates the uniquely enhanced corrosion resistance against the hot/humid and acidic environments,and counts as one peculiar feature of Nd-Ce-Fe-B magnets at high Ce substitution level,being distinct from previously reported Ce-free/lean RE-Fe-B.Simultaneously,the formation of continuous grain boundaries enhances the coercivity from 8.7to 12.5 k Oe with trace addition of(Nd,Pr)H_(x).Above findings may spur progress towards developing a high-performance Nd-Ce-Fe-B permanent magnet.

关键词： Abundant rare earth Ce Corrosion resistance REFe_(2) Coercivity microstructure

Synergistic effect of V_(2)O_(5)and Bi_(2)O_(3) on the grain boundary structure of high-frequency NiCuZn ferrite ceramics

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Journal of Advanced Ceramics 2022年第6期11卷 912-921页

作者： Xiuyuan FAN Guohua BAI Zhenhua ZHANG Qiming CHEN Jiaying JINa Jiafeng XUa Xuefeng ZHANG mi yan School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsKey Laboratory of Novel Materials for Information Technology of Zhejiang ProvinceZhejiang UniversityHangzhou 310027China Institute of Advanced Magnetic Materials College of Materials&Environmental EngineeringHangzhou Dianzi UniversityHangzhou 310012China

High-frequency soft magnetic ferrite ceramics are desired in miniaturized and efficient power electronics but remain extremely challenging to deploy on account of the power loss(Pcv)at megahertz frequencies.Here,we prepared NiCuZn ferrite with superior high-frequency properties by V_(2)O_(5)and Bi_(2)O_(3)synergistic doping,which proves to be a potent pathway to reduce Pcv of the ferrite at megahertz frequencies.The sample doped with 800 ppm V_(2)O_(5)and 800 ppm Bi_(2)O_(3)yielded the most optimized magnetic properties with a Pcv of 113 kW/m^(3)(10 MHz,5 mT,25℃),an initial permeability(μi)of 89,and a saturation induction(Bs)of 340 mT,which is at the forefront of the reported results.These outstanding properties are closely related to the notable grain boundary structure,which features a new type of nano-Bi_(2)Fe_(4)O_(9)phase around ferrite grains and a Ca/Si/V/O amorphous layer.Our results indicate great strides in correlating the grain boundary structure with multiple-ion doping and set the scene for the developing high-frequency soft magnet ferrites.

关键词： NiCuZn ferrite megahertz application grain boundary Bi_(2)Fe_(4)O_(9) ion doping

Understanding the efficient microwave absorption for Fe Co@ZnO flakes at elevated temperatures a combined experimental and theoretical approach

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Journal of Materials Science & Technology 2022年第30期125卷 212-221页

作者： Kangsen Peng Chuyang Liu Yuhan Wu Gang Fang Guoyue Xu Yujing Zhang Chen Wu mi yan School of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Silicon Materials Zhejiang UniversityHangzhou 310027China

Considerable microwave absorption performance at elevated temperatures is highly demanded in both civil and military fields.Single dielectric or magnetic absorbers are difficult to attain efficient and broadband microwave absorption at the high temperature range of 373 K-573 K,and the evolution mechanism of the microwave absorption is still unclear especially for the magnetic absorbers.Herein,ZnO coated flaky-FeCo composite is proposed to break through the bottleneck,which possesses microwave absorption(RLmicrowave absorption properties for the FeCo@ZnO flaky material at elevated temperature has been clearly disclosed by the composition and microstructure characterizations,electromagnetic performance measurements and first principles calculations for the first time.Moreover,the Poynting vector,volume loss density,magnetic field(H)and electric field(E)are simulated by HFSS to understand the interaction between EM waves and the samples at different temperatures,further elaborating the attenuation mechanism in high-temperature environment.This study provides guidance in designing and developing high-temperature microwave absorbers for the next generation.

关键词： Zn O coated flaky-FeCo High-temperature microwave absorption First principles calculation HFSS simulation

Utilization of molten chloride salt derived from MSWI fly ash washing as energy storage material:thermophysical properties and corrosion behavior

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Waste Disposal and Sustainable Energy 2022年第3期4卷 193-203页

作者： mi yan Yayong yang Jiahao Jiang Rendong Zheng Yi Ma Mohammad Khalid Haryo Wibowo Institute of Energy and Power Engineering Zhejiang University of TechnologyHangzhou310014China Zhejiang Carbon Neutral Innovation Institute Zhejiang University of TechnologyHangzhou310014China Hangzhou Linjiang Environmental Energy Co.Ltd. Hangzhou311225China Graphene and Advanced 2D Materials Research Group(GAMRG) School of Engineering and TechnologySunway UniversityBandar Sunway47500Malaysia

Fly ash,as a byproduct of municipal solid waste incineration,contains several kinds of pollutants,especially dissolvable salts that cause a severe challenge for fly ash disposal.Washing combined with cement kiln co-processing for fly ash disposal has been applied in China.After washing,the wastewater was evaporated to produce fly ash salt(FAS).In this study,FAS was mixed the KCl and LiCl to be used as molten chloride salt for energy storage material.Twenty-three types of molten salts with various ratios of FAS-KCl-LiCl were evaluated.Thermophysical properties(melting point and latent heat)and thermal stability of these salts were characterized.The increase in FAS fraction decreased the latent heat of molten salts.Among the tested samples,the best compatibility ratio of FAS:KCl:LiCl was 10:50:40(%,in weight),with latent heat of 108.7 J/g and melting point of 333℃.This molten salt also showed good thermal stability after 1–13 h of thermal experiments,and the mass loss was less than 2%after 5 heating cycles at 600℃.By corrosion test,FAS-KCl-LiCl(10:50:40,%in weight)could be more safely used in vessels made of nickel-based alloy,but it might cause corrosion risk for stainless steel.

关键词： Fly ash Molten salt Latent heat Stability Corrosion

Treatment of wastewater from food waste hydrothermal carbonization via Fenton oxidization combined activated carbon adsorption

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Waste Disposal and Sustainable Energy 2022年第3期4卷 205-218页

作者： Tianchi Shen mi yan Yuhao Xia Ruixiong Hu Yayong yang Cheng Chen Feng Chen Dwi Hantoko Institute of Energy and Power Engineering College of Mechanical EngineeringZhejiang University of TechnologyHangzhou310014China

Hydrothermal carbonization(HTC)of food waste can produce hydrochar for further utilization as high-quality fuel or carbon materials,but the by-product of liquid effluent,named HTC wastewater,has a high chemical oxygen demand(COD)content and other organic pollutants.This study focused on the feasibility of Fenton oxidation combined with activated carbon(AC)to reduce COD in HTC wastewater.The effects of different parameters including pH,dosage of hydrogen peroxide,molar ratio of Fe^(2+)/H_(2)O_(2),and reaction time were tested and discussed.Eventually,through the optimized Fenton oxidation(pH=3,H_(2)O_(2)dosage=1.5 mol/L,Fe^(2+)/H_(2)O_(2)=1:15,reaction time=60 min)combined optimized AC adsorption process(AC dosage=30 g/L),the COD value reduced from 42,000 mg/L to 3075 mg/L,indicating a COD removal efficiency of 92.7%and a color removal ratio of 91.9%,respectively.The comparison of GC/MS(gas chromatography mass spectrometer)and FTIR(Fourier transform infrared spectrometer)of liquid residual from different treatment methods also indicated that the types of organic substances in HTC wastewater were significantly reduced through Fenton oxidation and AC adsorption.

关键词： Food waste Hydrothermal carbonization Fenton Adsorption Wastewater