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Spontaneous magnetization and magnetic domain texture of strontium hexaferrite in equilibrium state

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Rare Metals 2022年第9期41卷 3019-3026页

作者： Dan liu Si-Da Jiang Li-Chen Wang ruo-shui liu Ming Zhang Tong-Yun Zhao Feng-Xia Hu Ji-Rong Sun Bao-Gen Shen School of Artificial Intelligence Beijing Technology and Business UniversityBeijing100048China Space Environment Simulation Research Infrastructure Harbin Institute of TechnologyHarbin150001China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341000China School of Physics Inner Mongolia University of Science and TechnologyBaotou014010China State Key Laboratory of Magnetism Institute of PhysicsChinese Academy of SciencesBeijing100190China

The spontaneous magnetization and equilibrium domain of SrFeOunder zero external field by micromagnetic simulation and experimental measurements were *** was found that the magnetic moment distribution was extremely sensitive to the grain size of strontium *** critical diameter from single-domain to multi-domain can be controlled by changing the thickness and diameter,which is the key to improve the permanent magnet properties.

关键词： properties. magnetization magnetic

Effects of dipolar interactions on the magnetic hyperthermia of Zn_(0.3)Fe_(2.7)O_(4) nanoparticles with different sizes

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Chinese Physics B 2021年第1期30卷 497-501页

作者： Xiang Yu Yan Mi Li-Chen Wang Zheng-Rui Li Di-An Wu ruo-shui liu Shu-Li He Department of Physics Capital Normal UniversityBeijing 100048China

Tumor-targeted magnetic hyperthermia has recently attracted much *** nanoparticles(NPs) are heat mediator nanoprobes in magnetic hyperthermia for cancer *** this paper,single cubic spinel structural Zn_(0.3)Fe_(2.7)O_(4) magnetic NPs with sizes of 14 nm-20 nm were synthesized,followed by coating with SiO_(2) *** SLP value of Zn_(0.3)Fe_(2.7)O_(4)/SiO_(2) NPs below 20 nm changes non-monotonically with the concentration of solution under the alternating current(AC) magnetic field of 430 kHz and 27 kA/*** values of all Zn_(0.3)Fe_(2.7)O_(4)/SiO_(2) NPs appear a peak value with change of solution *** solution concentrations with optimal SLP value decrease with increasing magnetic core *** work can give guidance to the better prediction and control of the magnetic hyperthermia performance of materials in clinical applications.

关键词： magnetic nanoparticles dipolar interaction magnetic hyperthermia

Effect of Magnetic Anisotropy on Magnetic Thermal Induction of Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4 Nanoparticles

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Chinese Physics Letters 2019年第3期36卷 74-77页

作者： Chen-Hui Lv Li-Chen Wang Zheng-Rui Li Xiang Yu Yan Mi ruo-shui liu Kai Li Dan-Li Li Shu-Li He Department of Physics Capital Normal University Department of Chemistry Capital Normal University

Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4 series magnetic nanoparticles are prepared by the high-temperature organic solvent method, and Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4@SiO_2 composite nanoparticles are prepared by the reverse microemulsion method. The as-prepared samples are characterized, and the results show that the magnetic anisotropy constant of nanoparticles increases with the cobalt content, and the magnetic thermal induction shows a trend of increasing first and then decreasing. The optimal magnetic thermal induction is obtained at x = 0.12 with a specific loss power of 2086 w/gmetal, which is a bright prospect in clinical magnetic hyperthermia.

关键词： Anisotropy Magnetic Induction

Table-Like Large Magnetocaloric Effect in the Misch Metal RSi Compound

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Chinese Physics Letters 2020年第1期37卷 88-91页

作者： ruo-shui liu Jun liu Li-Chen Wang Zheng-Rui Li Xiang Yu Yan Mi Qiao-Yan Dong Kai Li Dan-Li Li Chen-Hui Lv Li-Feng liu Shu-Li He Department of Physics Capital Normal UniversityBeijing 100048 State Key Laboratory for Magnetism Institute of PhysicsChinese Academy of SciencesBeijing 100190 Department of Chemistry Capital Normal UniversityBeijing 100048

Magnetic properties and the magnetocaloric effect(MCE)of the RSi(R=Ce,Pr,Nd)compounds made of Misch metal(MM)are *** transitions are found at 12K and *** variation generated large MCE and two peaks are found in the magnetic entropy change(△S)curves,which correspond to the two transition *** maximum values of the magnetic entropy changes(△S)are found to be-5.1 J/(kg·K)and-9.3 J/(kg·K)for the field ranges of 0-2 T and 0-5 T,*** large AS as well as ultra-low price of MM make(MM)Si a competitive magnetic refrigerant candidate for low temperature in Eriksson cycle.

关键词： entropy magnetic competitive

A simple path to ambient temperature ionic H^(-)superconductors

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Science China Chemistry 2024年第1期67卷 321-322页

作者： Bingru liu Shiyuan liu Jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Hydride ion(H^(-))has high polarizability(α_(H^(-))=10.17A^(3))and high redox potential(H^(-)/H_(2):-2.3 V),and therefore is an attractive energy carrier[1,2].The H^(-)superconductors play a crucial role in the devel... 详细信息

关键词： attractive ambient superconductors

Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-N-C catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao liu Huanhuan He Qingtao liu Xin Wan Jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Space and Environment Beihang UniversityBeijing102206China Tianmushan Laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–N–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,Cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–N–C *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–N_(3)Se_(1)/NC and Fe–N_(3)Se_(1)/NC demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-N-C catalysts Hetero-atom doping Doping position Enhancement mechanism

A proposal for detecting weak electromagnetic waves around 2.6μm wavelength with Sr optical clock

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Chinese Physics B 2024年第4期33卷 452-457页

作者：韩弱水王伟汪涛 Department of Physics and Chongqing Key Laboratory for Strongly Coupled PhysicsChongqing UniversityChongqing 401331China Center of Modern Physics Institute for Smart City of Chongqing University in LiyangLiyang 213300China State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi UniversityTaiyuan 030006China

Infrared signal detection is widely used in many *** to the detection principle,however,the accuracy and range of detection are *** to the ultra stability of the^(87)Sr optical lattice clock,external infrared electromagnetic wave disturbances can be responded *** the ac Stark shift of the clock transition,we propose a new method to detect infrared *** to our calculations,the theoretical detection accuracy in the vicinity of its resonance band of 2.6μm can reach the order of 10-14W,while the minimum detectable signal of common detectors is on the order of 10^(-10)W.

关键词： infrared signal detection ^(87)Sr optical lattice clock ac Stark shift ultra stability

Boosting the Oxygen Reduction Performance of Fe–N–C Catalyst Using Zeolite as an Oxygen Reservoir

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Transactions of Tianjin University 2024年第5期30卷 428-435页

作者： Weihao liu Qingtao liu Xin Wan Jianglan shui School of Materials Science and Engineering Beihang University School of Space and Environment Beihang University Tianmushan Laboratory

Non-precious metal electrocatalysts（such as Fe–N–C materials） for the oxygen（O2） reduction reaction demand a high catalyst loading in fuel cell devices to achieve workable performance. However, the extremely low solubility of O2in water creates severe mass transport resistance in the thick catalyst layer of Fe–N–C catalysts. Here, we introduce silicalite-1 nanocrystals with hydrophobic cavities as sustainable O2reservoirs to overcome the mass transport issue of Fe–N–C catalysts. The extra O2supply to the adjacent catalysts significantly alleviated the negative effects of the severe mass transport resistance. The hybrid catalyst（Fe–N–C@silicalite-1） achieved a higher limiting current density than Fe–N–C in the half-cell test. In the H2–O2and H2–air proton exchange membrane fuel cells, Fe–N–C@silicalite-1 exhibited a 16.3% and 20.2% increase in peak power density compared with Fe–N–C, respectively. The O2-concentrating additive provides an effective approach for improving the mass transport imposed by the low solubility of O2in water.

关键词： Fe–N–C catalyst Fuel cell Mass transport Oxygen reduction reaction Oxygen reservoir

Critical role of carbon support in metal nanoaggregate facilitating Fe-N-C catalyst for PEM fuel cell application

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Journal of Energy Chemistry 2024年第10期97卷 669-676,I0014页

作者： Liming Guo Xin Wan Qingtao liu Xiaofang liu Jiaxiang Shang Ronghai Yu Jianglan shui School of Materials Science and Engineering Beihang UniversityBeijing 100191China Tianmushan Laboratory Hangzhou 310023ZhejiangChina

Metal nanoaggregates can simultaneously enhance the activity and stability of Fe-N-C catalysts in proton-exchange-membrane fuel cells(PEMFC).Previous studies on the relevant mechanism have focused on the direct interaction between FeN_(4)active sites and metal ***,the role of carbon support that hosts metal nanoaggregates and active sites has been ***,a Fe-N-C catalyst encapsulating inactive gold nanoparticles is prepared as a model catalyst to investigate the electronic tuning of Au nanoparticles(NPs)towards the carbon *** NPs donate electrons to carbon support,making it rich inπelectrons,which reduces the work function and regulates the electronic configuration of the FeN_(4)sites for an enhanced ORR ***,the electron-rich carbon support can mitigate the electron depletion of FeN_(4)sites caused by carbon support oxidation,thereby preserving its high *** yield and accumulation of H_(2)O_(2)are thus alleviated,which delays the oxidation of the catalyst and benefits the *** to the electron-rich carbon support,the composite catalyst achieves a top-level peak power density of 0.74 W/cm^(2) in a 1.5 bar H_(2)-air PEMFC,as well as the improved *** work elucidates the key role of carbon support in the performance enhancement of the FeN-C/metal nanoaggregate composite catalysts for fuel cell application.

关键词： Fuel cells Oxygen reduction reaction Fe-N-C Hetero-structure catalyst Carbon support