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The microstructure and magnetization reversal behavior of melt-spun (Nd_(1-x)Ce_x)-Fe-B ribbons

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Journal of Rare Earths 2018年第1期36卷 95-98页

作者： liwei song nengjun yu minggang zhu qiang wang wei li division of functional materials central iron and steel research instituteBeijing 100081China key laboratory of national education ministry for electromagnetic processing of materials northeastern universityShenyang 110819China school of materials science and engineering northeastern universityShenyang 110819China

In this study, the alloy ingots with nominal compositions of （Nd1_xCex）31FebalCoo.2Gao.1B （x = 0, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%） were prepared and then melt-spun to form nanocrystalline ribbons at the wheel speed of 20 m/s. XRD results show that all melt-spun ribbons exhibit the tetragonal structure （Nd,Ce）2Fe14B phase with the space group P42]rnmm. The Curie temperature and lattice constant decrease with the increase of Ce content. The Curie temperature decreases gradually from 306 to 247 ~C with the increase of Ce content. Those results indicate that Ce element has been incorporated into Nd2Fe14B main crystalline phase and formed （Ce,Nd）-Fe-B hard magnetic phase. It is also found that the remanence ratio （Mr/Ms） decreases from 0.693 to 0.663 and the coercivity （Hc） decreases from 18.7 to 14.2 kOe with the increase of Ce content. However, a relatively high coercivity of 18.3 kOe for （Ndl xCex）*** （x = 0.2） melt-spun ribbon is achieved. The coercivity is sensitive to microstructure. The AFM patterns show the sample （x - 0.2） has the most uniform and finest micro- structure. The magnetization reversal behavior （0M plots） is discussed in detail. The positive 0M value is observed in every sample, which confirms the existence of exchange coupling interaction. Evidently, the OM maximum value reaches 0.9 in the sample （x - 0.2）. It is indicated that the intergranular exchange coupling effect is the strongest, which is consistent with coercivity enhancing.

关键词： Ce contentMelt-spun ribbonsHigh coercivityMicrostructureRare earthsMagnetization reversal

Transport mechanism in chemically reactive hybrid nanofluid flow containing gyrotactic micro-organisms over a curved oscillatory surface

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 177-192页

作者： M.NAVEED M.IMRAN T.ASGHAR Z.ABBAS Department of Mathematics Division of Science and TechnologyUniversity of Education Department of Mathematics The Islamia University of Bahawalpur

This paper examines the transport analysis, including both heat transfer and mass transfer, in hybrid nanofluid flow containing gyrotactic microorganisms towards a curved oscillatory surface. The influence of magnetic fields is also inspected in terms of their physical characteristics. To depict the phenomena of transport, modified versions of both Fick's and Fourier's laws are used. Additionally, the characteristics of both heterogeneous and homogeneous chemical reactions are also incorporated. Utilizing a curvilinear coordinate system, the flow problem is formulated as partial differential equations(PDEs)for momentum, concentration, microorganism field, and energy. An analytical solution to the obtained flow equations is achieved utilizing the homotopy analysis method(HAM).The effects of significant flow parameters on the pressure and microorganism fields, velocity, oscillation velocity, concentration, and temperature distributions are shown via graphs. Furthermore, the variations in skin friction, mass transfer rate, heat transfer rate, and local motile number due to different involved parameters are presented in tables and are analyzed in detail. Graphical results indicate that the curves of velocity and temperature fields are enhanced as the values of the solid volume fraction variables *** is also verified that the concentration rate field decreases as the values of the homogeneous reaction strength parameter and the radius of curvature parameter increase, and it increases with the Schmidt number and the heterogeneous reaction strength *** outcomes show a favorable response of the motile number to advanced values of the Peclet number, the Schmidt number, the microorganism difference parameter, and the bio-convective Lewis number.

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Fabrication of ultrafine ZnFe2O4 nanoparticles for efficient photocatalytic reduction CO2 under visible light illumination

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Journal of materials Science & Technology 2018年第12期34卷 2331-2336页

作者： Jun xiao Weiyi Yang Shuang Gao Caixia Sun Qi Li Environment functional materials division Shenyang National Laboratory for Materials ScienceInstitute of Metal ResearchChinese Academy of SciencesShenyong 110016China University ofChineseAcademy of Sciences Beijing 100049China division of Energy and Environment Graduate School of ShenzhenTsinghua UniversityShenzhen 518055China Key Laboratory of New Metallic functional materials and Advanced Surface Engineering in Universities of Shandong Qingdao Binhai UniversityQingdao 266555China School of Mechanical and Electronic Engineering Qingdao Binhai UniversityQingdao 266555China

A one-pot, solvent-thermal process was used to create the ultrafine ZnFe2O4nanoparticles *** the solvent-thermal process, the in situ self-forming NaCl not only served as a "cage" to confine the ion diffusion, but also acted as a microreactor for nanocrystallite growth. An average particle size of ～10 nm and a high-specific surface area of～112.9 m2/g were observed for the ultrafine ZnFe2O4nanoparticles Owing to the synergistic effect of ultrafine particle size, the full utilization of the visible light region and high conduction band(CB) position, ultrafine ZnFe2O4photocatalyst displayed an efficient photocatalytic CO2reduction under visible light illumination. Besides, the ultrafine ZnFe2O4photocatalyst showed high production selectivity for CH3CHO and C2H5OH generation in aqueous CO2/NaHCO3solution. This work may provide a new idea for the synthesis of new high-efficiency photocatalysts.

关键词： Ultrafine nanoparticles Photocatalytic CO_2 reduction Visible light ZnFe_2O_4 photocatalyst In situ self-formed "cage"

Temperature stability and microstructure of ultra-high intrinsic coercivity Nd-Fe-B magnets

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Rare Metals 2008年第4期27卷 358-361页

作者： HU Zhihua CHENG Xinghua ZHU Minggang LI Wei LIAN Fazeng Key Laboratory of the Ministry of Education of China for Anisotropy and Texture of materials Northeastern University Shenyang 110004 China division of functional materials Central Iron ＆ Steel Research Institute Beijing 100081 China Advanced Technology and materials Co. Ltd. Beijing 100081 China

The variations of intrinsic coercivity and remanence of sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity were investigated. The results showed that the intrinsic coercivity and remanence declined simultaneously with increasing temperature, but the squareness of the magnets has hardly been changed. The temperature coefficients of remanence （α） and coercivity （β） for the magnets were calculated by two different methods, and the variations of the temperature coefficients and the microstructure of sintered Nd-Fe-B magnets were analyzed. The temperature coefficients of remanence （α） and coercivity （β） for the sintered magnets are very small, and the existence of fine microstructure is necessary to obtain sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity.

关键词： Nd-Fe-B magnets intrinsic coercivity sintering remanence temperature coefficient

Cancer cell detection and imaging: MRI-SERS bimodal splat-shaped Fe_3O_4/Au nanocomposites

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Chinese Chemical Letters 2019年第1期30卷 87-89页

作者： Xinmei Zhao Leyong Zeng Narayan Hosmane Yan Gong Aiguo Wu CAS Key Laboratory of Magnetic materials and Devices & division of functional materials and Nanodevices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Zhejiang Pharmaceutical College Department of Chemistry & Biochemistry Northern Illinois University Ningbo Eye Hospital

The development of multifunctional contrast agents contributes significant character in the diagnosis of cancer. However, still efforts are required to design and improve the biocompatibility of contrast agents for early detection of cancer. Herein, we synthesized splat shape Fe_3O_4/Au nanocomposites for multimode biomedical applications. Transmission electron microscopy(TEM) results showed that the splat-like Fe_3O_4/Au structure was in the range of 130 nm and homogeneously distributed in the aqueous medium. The nanocomposites were incubated with MCF-7 cells to investigate the magnetic resonance imaging(MRI) and surface-enhanced Raman scattering(SERS) activities. The excellent T_2 MRI and enhanced SERS properties were obtained without any cytotoxicity. These results demonstrated that assynthesized splat-shaped Fe_3O_4/Au nanocomposites may be a promising MRI/SERS dual probe for the tumor detection.

关键词： Fe3O4/Au MRI SERS Cell detection MCF-7

A facile fabrication route for binary transition metal oxide-based Janus nanoparticles for cancer theranostic applications

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Nano Research 2018年第10期11卷 5735-5750页

作者： M. Zubair Iqbal Wenzhi Ren Madiha Saeed Tianxiang Chen Xuehua Ma Xu Yu Jichao Zhang Lili Zhang Aiguo Li Aiguo Wu iang Province & Division of Functional Materials and Nano devices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China ShanghaiSynchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201204 China

Janus nanoparticles （JNPs） have multiple configurations for molecular imaging, targeting, and therapeutic effects on cancers; these properties have made these particles attractive for biomedical applications. Nonetheless, smart strategies for the controlled synthesis in a liquid phase and exploration of the appropriate applications of JNPs remain a challenge. In this study, a unique liquid-phase method was applied to fabricate Mn3O4-TiO2/ZnO/Fe3O4 multifunctional binary transition metal oxide-based JNPs, using the concept of epitaxial growth and lattice mismatch among synthesized materials. Transmission electron microscopy and scanning transmission electron microscopy results revealed that the created materials are embedded in the form of dimers with good dispersion and homogeneous growth in a nonpolar solvent. Pluronic F-127-coated MnBO4- TiO2 JNPs were utilized as a contrast agent in T1-weighted magnetic resonance imaging （MRI） and in photodynamic therapy （PDT） for cancers in vitro and in vivo. In vivo T1-weighted MRI of the heart, liver, and kidneys in mice after intravenous injection of the nanoparticles revealed high sensitivity and biocompatibility of as-synthesized Mn3O4--TiO2 JNPs. Results of synchrotron X-ray fluorescence microscopy mapping showed the stability of the nanocomposites and efficiency of penetration into the cytoplasm and perinuclear area. Inorganic TiO2 photosensitizers showed promising tumor ablation performance in PDT in vitro and in vivo at low intensity of UV irradiation （5.6 ***-2） because of their ultrasmall size and photodegradable stability. These results reveal that multifunctional Mn3O4-TiO2 JNPs enhance a T1-weighted MRI contrast and have excellent properties for PDT and therefore, may be a novel agent for cancer theranostics.

关键词： Janus nanostructures manganese oxide magnetic resonance imaging photodynarnic therapy breast cancer

Effect of Firing Temperature on the Electromagnetic Properties of Electronic Transformer Cores Developed by Using Nanosized Mn–Zn Ferrite Powders

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 159-163页

作者： Hassan Waqas Ammad Hussain Qureshi Muhammad Shahzad materials division Directorate of Technology PINSTECH

Current investigation deals with the effect of grain growth process as a function of sintering temperature on the electromagnetic properties （initial permeability, impedance, and gain） of Mn-Zn ferrite （MZF） cores （toroids）. By employing auto combustion process, nanosized [（20 ± 5） nm] MZF powders were synthesized and toroid shape cores were obtained after subsequent calcination and firing （sintering） process. It was observed that the submicron structure （0.5 μm） achieved in the ferrite core sintered at 1,000 ℃ was gradually transformed into micron size grains by increasing the firing temperature i.e., 1,100, 1,200, and 1,350 ℃. The results reveal that MZF core sintered at low temperature （1,000 ℃） showed high impedance, low initial permeability, and narrow working frequency range i.e., 3-15 MHz. However, the improvement in initial permeability, sintered density, and operational frequency range （100 kHz-17 MHz） was observed at high temperature （1,350 ℃） firing in the inert environment. This synthesized MZF core is more suitable for miniaturized switch mode power supply applications.

关键词： Mn-Zn ferrites Nanosized powders Impedance Sintering

Thermal stability of bimodal grain structure in a cobalt-based superalloy subjected to high-temperature exposure

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Rare Metals 2021年第4期40卷 877-884页

作者： Cheng-Lin Li Jeong Mok Oh Seong-Woo Choi Xin-Ming Mei Jae-Keun Hong Jong-Taek Yeom Qing-Song Mei Zhen-Tao Yu Chan Hee Park School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China Advanced Metals division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Institute of Advanced Wear and Corrosion Resistant and functional materials Jinan UniversityGuangzhou 510632China

The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni(wt%) alloy with a bimodal grain(BG) *** BG structure consisting of fine grains(FGs) and coarse grains(CGs) is thermally stable under high-temperature exposure treatments of 760℃ for 100 h and 870℃ for 100-1000 *** size of both FGs and CGs remains no significant changes after thermal exposure *** microstructural stability is associated with the slow kinetics of grain growth and the pinning of *** thermal stability enables to maintain the BG structures,leading to the same mechanical properties as the sample without thermal exposure *** particular,the BG alloy samples after thermal exposure treatment exhibit superior mechanical properties of both high strength and high ductility compared to the unimodal grain(UG) structured *** BG structure of the alloy samples after thermal exposure is capable of avoiding severe loss of ductility and retaining high *** specifically,the ductility of the BG alloy samples after thermal exposure treatments of 870℃ for 500-1000 h is ten times higher(44.6% vs.3.5% and 52.6% vs.5.0%) than that of the UG *** finding in the present work may give new insights into high-temperature applications of the Co-20 Cr-15 W-10 Ni alloy and other metallic materials with a BG structure.

关键词： Thermal stability Bimodal grain structure High-temperature exposure Cobalt-based superalloy

Interfacial state induced ultrasensitive ultraviolet light photodetector with resolved flux down to 85 photons per second

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Nano Research 2015年第4期8卷 1098-1107页

作者： Yong-Qiang Yu Lin-Bao Luo Ming-Zheng Wang Bo Wang Long-Hui Zeng Chun-Yan Wu Jian-Sheng Jie Jian-Wei Liu Li Wang Shu-Hong Yu School of Electronic Science and Applied Physics Anhui Provincial Key Laboratory of Advanced Functional Materials and Devices Hefei University of Technology Hefei Anhui 230009 China Institute of functional Nano & Soft materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based functional materials & Devices Soochow University Suzhou Jiangsu 215123 China division of Nanomaterials & Chemistry Hefei National Laboratory for Physical Sciences at Microscale Department of Chemistry University of Science and Technology of China Hefei 230026 China

We present an ultrasensitive ultraviolet （UV） detector based on a p-type ZnS nanoribbon （NR）/indium tin oxide （ITO） Schottky barrier diode （SBD）. The device exhibits a pseudo-photovoltaic behavior which can allow the SBD to detect UV light irradiation with incident power of 6 × 10^-17 W （-85 photons/s on the NR） at room temperature, with excellent reproducibility and stability. The corresponding detectivity and photoconductive gain are calculated to be 3.1 × 10^20 ***1/2.W^-1 and 6.6 × 10^5, respectively. It is found that the presence of the trapping states at the p-ZnS NWITO interface plays a crucial role in determining the ultrahigh sensitivity of this nanoSBDs. Based on our theoretical calculation, even ultra-low photon fluxes on the order of several tens of photons could induce a significant change in interface potential and consequently cause a large photocurrent variation. The present study provides new opportunities for developiphigh-performance optoelectronic devices in the future.

关键词： II-VI group detectivity Schottky barrier diode optoelectronic device interfacial states