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Brightening heavily doped upconversion nanoparticles by tuning characteristics of core-shell structures

Journal of Rare Earths 2024年第5期42卷 947-954,I0005页

作者： Yangyang Niu Zhihao Bao Yuqin Gao Mengchao Guo Jingyao Liu Jinjun Shao Min Lu Ze Yuan Xiaoji Xie School of Flexible Electronics(Future Technologies)&institute of advanced materials(IAM) Nanjing Tech UniversityNanjing211816China

Heavily doped upconversion nanoparticles(UCNPs)potentially have exceptional photon upconversion abilities that are promising for diverse applications,such as lasing and super-resolution microscopy.However,heavily doped UCNPs typically can only offer mediocre upconversion luminescence intensity,and there still lacks general guidelines for the design and synthesis of heavily doped UCNPs.Herein,in order to boost the upconversion luminescence of heavily doped UCNPs,we studied the influence of characteristics of the core-shell structure on heavily doped UCNPs'upconversion luminescence.We find that some empirical guidelines derived from conventional UCNPs are not suitable for heavily doped UCNPs.Using NaYbF_(4):Tm@NaYF_(4) core-shell UCNPs with a high concentration of Yb_(3+)as a representative,our studies reveal that a rather thick inert NaYF4 shell is needed to protect the UCNPs from surface quenching,and the upconversion luminescence may undergo the cooperative sensitization process,which should be due to the highly concentrated Yb~(3+)dopant.In addition,the upconversion luminescence of heavily doped NaYbF4:Tm UCNPs exhibits no obvious dependence on the type of inert shell.Furthermore,our results show that confining both Yb~(3+)and Tm~(3+)dopants in a thin layer(known as theδ-doping strategy)does not work well in the heavily doped UCNPs.Accordingly,we propose a NaYbF_(4):Tm@NaYbF_(4)@NaYF_(4) core-shell-shell structure to enhance the luminescence of heavily doped UCNPs,by weakening the dissipation of excitation energy and strengthening the absorption.These findings should be helpful to establish general design principles for developing the brightest possible UCNPs that can meet the requirements of various applications.

关键词： Luminescence Upconversion Nanomaterials Rare earths Lanthanide doping

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Graphene binding on black phosphorus enables high on/off ratios and mobility

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National Science Review 2024年第2期11卷 188-195页

作者： Fanrong Lin Zhonghan Cao Feiping Xiao Jiawei Liu Jiabin Qiao Minmin Xue Zhili Hu Ying Liu Huan Lu Zhuhua Zhang Jens Martin Qingjun Tong Wanlin Guo Yanpeng Liu Key Laboratory for Intelligent Nano materials and Devices of Ministry of Education State Key Laboratory of Mechanics and Control of Mechanical Structures and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics Centre for advanced 2D materials National University of Singapore School of Physics and Electronics Hunan University Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and MeasurementSchool of PhysicsBeijing Institute of Technology Leibniz institute für Kristallzüchtung

Graphene is one of the most promising candidates for integrated circuits due to its robustness against short-channel effects, inherent high carrier mobility and desired gapless nature for Ohmic contact, but it is difficult to achieve satisfactory on/off ratios even at the expense of its carrier mobility, limiting its device applications. Here, we present a strategy to realize high back-gate switching ratios in a graphene monolayer with well-maintained high mobility by forming a vertical heterostructure with a black phosphorus multi-layer. By local current annealing, strain is introduced within an established area of the graphene, which forms a reflective interface with the rest of the strain-free area and thus generates a robust off-state via local current depletion. Applying a positive back-gate voltage to the heterostructure can keep the black phosphorus insulating, while a negative back-gate voltage changes the black phosphorus to be conductive because of hole accumulation. Then, a parallel channel is activated within the strain-free graphene area by edge-contacted electrodes, thereby largely inheriting the intrinsic carrier mobility of graphene in the on-state. As a result, the device can provide an on/off voltage ratio of >10～3 as well as a mobility of ～8000 cm2V-1s-1at room temperature, meeting the low-power criterion suggested by the International Roadmap for Devices and Systems.

关键词： graphene on/offratio mobility black phosphorus reflective interface

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Fatigue Crack Initiation and Propagation Dominated by Crystallographic Factors in TiB/near a-Ti

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 763-776页

作者： Fanchao Meng Rui Zhang Shuai Wang Fengbo Sun Run Chen Lujun Huang Lin Geng School of materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Waikato Centre for advanced materials and Manufacturing School of EngineeringUniversity of WaikatoHamilton 3240New Zealand State Key Laboratory of advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Discontinuously reinforced titanium matrix composites(DRTMCs)with a network structure have been extensively researched due to their superior combination of strength and ductility.However,their fatigue performance has remained unknown.In order to elucidate the fatigue behavior of DRTMCs,a tension-tension fatigue test was performed on a TiB/nearα-Ti composite with network structure.The results showed that the variability of fatigue lifetime increased as the stress level decreased.Fractography analysis indicated that fatigue crack initiation was associated with facet formation,while the subsequent propagation was hindered by the network structure comprising TiB whiskers and silicides.Crystallographic characterization further revealed that facets formed due to a combination of shear and normal stress.The reduction in fatigue lifetime was attributed to an increase in the effective slip length,which was influenced by the orientation of grains near the crack-initiation sites toward basal slip in the life-limiting specimen.Quasi in situ observation suggested that the crack initiation was facilitated by both basal and prismatic slip ofα-Ti as well as fracture of TiBw.Crack propagation was found to be associated with basal and prismatic slip systems with high Schmid factors,regardless of whether the crack was intergranular or intragranular.

关键词： Titanium matrix composite TiBw Fatigue lifetime variability Crack initiation Crack propagation

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Deep insight of unique phase transition behaviors and mechanism in Zr_(2)Co-H isotope system with ultra-low equilibrium pressure

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Rare Metals 2024年第1期43卷 212-224页

作者： Yang Liu Pan-Pan Zhou Xue-Zhang Xiao Jia-Cheng Qi Jia-Peng Bi Tiao Ying Xing-Wen Feng Yan Shi Wen-Hua Luo Li-Xin Chen State Key Laboratory of Silicon materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China institute of materials China Academy of Engineering PhysicsMianyang 621907China Key Laboratory of advanced materials and Applications for Batteries of Zhejiang Province Hangzhou 310013China

Efficient capture,safe storage and release of tritium from the international thermonuclear experimental reactor(ITER) reaction exhaust gas is a perplexing problem,and the development of an efficient tritium-getter material with ultra-low hydrogenation equilibrium pressure is considered as a reliable way.In this work,Zr_(2)Co alloy was selected as a tritium-getter material and prepared through induction levitation melting.Fundamental performance test results show that Zr_(2)Co exhibits an ultra-low hydrogenation equilibrium pressure of 3.22 × 10^(-6) Pa at 25℃ and excellent hydriding kinetics under a low hydrogen pressure of 0.005 MPa.Interestingly,unique phase transition behaviors were presented in Zr_(2)Co-H system.Specifically,Zr_(2)CoH_(5) formed by Zr_(2)Co hydrogenated at room temperature is initially decomposed into ZrH_(2) and ZrCoH_(3) at200 ℃.With the temperature increasing to 350 ℃,ZrCoH_(3)is dehydrogenated to ZrCo,and then ZrCo further reacts with ZrH_(2) at 650 ℃ to reform Zr_(2)Co and hydrogen.Among the staged phase transition pathways during dehydrogenation,the decomposition of Zr_(2)CoH_(5) occurs preferentially,which is well accordance with both the smallest reaction energy barrier and the maximum reaction spontaneity that are determined respectively from kinetics activation energy and thermodynamics Gibbs free energy.Furthermore,first principles calculation results indicate that the stronger binding of hydrogen in interstitial environments of ZrCoH_(3)and ZrH_(2) triggers the hydrogen-stabilized phase transformation of Zr_(2)CoH_(5).The unique phase transition mechanisms in Zr_(2)Co-H system can shed light on the further exploration and regulation of analogous staged phase transition of hydrogen storage materials.

关键词： Zr_(2)Co alloy Tritium-getter materials Ultralow equilibrium hydrogen pressure Phase transition mechanism

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SnS2 nanosheets decorated SnO2 hollow multishelled nanostructures for enhanced sensing of triethylamine gas

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Rare Metals 2024年第5期43卷 2339-2348页

作者： Wen-Di Liu Ya Xiong Ao Shen Xin-Zhen Wang Xiao Chang Wen-Bo Lu Jian Tian School of materials Science and Engineering Shandong University of Science and Technology College of Physics Qingdao University Zernike institute for advanced materials University of Groningen

Highly sensitive,fast and low-temperature detection of triethylamine （TEA） gas based on Sn O2is attractive yet remains challenging.Herein,Sn S2nanosheets （NSs）/Sn O2hollow multishelled structures （Ho MSs）-based sensors are designed by the synthesis of Sn O2Ho MSs,followed by in situ sulfuration with thioacetamide.By varying the thioacetamide levels,Sn S2/Sn O2heterostructures with different Sn S2contents were obtained and their TEA gas sensing performances were investigated.

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Design of advanced porous silver powder with high-sintering activity to improve silicon solar cells

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Nano Research 2024年第4期17卷 3189-3197页

作者： Yongsheng Li Ziwei Chen Rui Zhou Wenguang Zhao Mu Li Jun Chen Zhongyuan Huang Jian Liu Yuhang Li Maolin Yang Minghan Yu Dong Zhou Yuan Lin Feng Pan School of advanced materials Peking UniversityShenzhen Graduate SchoolShenzhen 518055China institute of advanced Science Facilities Shenzhen 518107China institute of Zhejiang University-Quzhou Quzhou 324000China Key Laboratory of Photochemistry Institute of ChemistryChinese Academy of SciencesBeijing 100190China institute of materials Research(IMR) Tsinghua UniversityTsinghua Shenzhen International Graduate SchoolShenzhen 518055China School of materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Silver(Ag)paste is widely used in semiconductor metallization,especially in silicon solar cells.Ag powder is the material with the highest proportion in Ag paste.The morphology and structure of Ag powder are crucial which determine its characteristics,especially for the sintering activity.In this work,a simple method was developed to synthesize a type of microcrystalline spherical Ag particles(SP-A)with internal pores and the structural changes and sintering behavior were thoroughly studied by combining ultra-small-angle X-ray scattering(USAXS),small-angle X-ray scattering(SAXS),in-situ heating X-ray diffraction(XRD),focused ion beam(FIB),and thermal analysis measurement.Due to the unique internal pores,the grain size of SP-A is smaller,and the coefficient of thermal expansion(CTE)is higher than that of traditional solid Ag particles.As a result,the sintering activity of SP-A is excellent,which can form a denser sintered body and form silver nanoparticles at the Ag–Si interface to improve silver silicon contact.Polycrystalline silicon solar cell built with SP-A obtained a low series resistance(Rs)and a high photoelectric conversion efficiency(PCE)of 19.26%.These fill a gap in Ag particle structure research,which is significant for the development of high-performance electronic Ag particles and efficient semiconductor devices.

关键词： silver particles small angle X-ray scattering(SAXS) pore size distribution in-situ heating X-ray diffraction(XRD) sintering silicon solar cells

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Design of novel RGO/2D strip-like ZIF-8/DMAOP ternary hybrid structure towards high-efficiency microwave absorption, active and passive anti-corrosion, and synergistic antibacterial performance

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Nano Research 2024年第3期17卷 913-926页

作者： Tanlin Chen Yingrui Tian Zihao Guo Yao Chen Qing Qi Fanbin Meng Key Laboratory of advanced Technologies of materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Shenzhen institute of Southwest Jiaotong University Shenzhen 518000China

In order to meet the requirements of the marine environment for microwave absorption(MA)materials,we put forward the strategy of constructing multi-functional composite materials,which integrate microwave absorption,anti-corrosion,and antibacterial properties.Herein,graphene oxide(GO)was used as a template to induce the growth of zeolitic imidazolate framework-8(ZIF-8),simultaneously as a two-dimensional(2D)nanocontainers to load corrosion inhibitors to achieve pH-responsive and self-healing properties.Finally,quaternary ammonium salt(dimethyl octadecyl(3-trimethoxylsilyl propyl)ammonium chloride(DMAOP))and sodium ascorbate(VCNa)were introduced to achieve synergistic antibacterial activity and the reduction of GO.The 2D strip-like structure of ZIF-8 was due to the confined growth induced by the electrostatic attraction between ZIF-8 and GO sheets.The as-obtained reduced GO(RGO)/ZIF-8/DMAOP5 exhibited excellent microwave absorption(MA)properties,with a minimum reflection loss(RL)value of-47.08 dB at 12.73 GHz when the thickness was 2.8 mm.Moreover,the effective absorption bandwidth reached 6.84 GHz.After soaking in 3.5%NaCl solution for 35 days,the RGO/ZIF-8/DMAOP5-0.7%coating still achieved an impedance value of 4.585×107Ω·cm^(2) and a protective efficiency of 99.994%,providing superior anti-corrosion properties.In addition,fantastic antibacterial activity was obtained,with the antibacterial rates of RGO/ZIF-8/DMAOP_(10) reaching 99.39%and 100%against Escherichia coli and Staphylococcus aureus.This work could open new avenues towards the development of a new generation of multifunctional MA materials.

关键词： two-dimensional(2D)strip-like zeolitic imidazolate framework-8(ZIF-8) microwave absorption active and passive anti-corrosion antibacterial

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Microstructure and forming mechanism of metals subjected to ultrasonic vibration plastic forming: A mini review

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International Journal of Minerals,Metallurgy and materials 2024年第6期31卷 1322-1332页

作者： Qinghe Cui Xuefeng Liu Wenjing Wang Shaojie Tian Vasili Rubanik Vasili Rubanik Jr. Dzmitry Bahrets Beijing advanced Innovation Center for materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China institute for advanced materials and Technology University of Science and Technology BeijingBeijing 100083China institute of Technical Acoustics National Academy of SciencesVitebsk 210009Belarus

Compared with traditional plastic forming,ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the workpiece.This technology has a very broad application prospect in industrial manufactur-ing.Researchers have conducted extensive research on the ultrasonic vibration plastic forming of metals and laid a deep foundation for the development of this field.In this review,metals were classified according to their crystal structures.The effects of ultrasonic vibration on the microstructure of face-centered cubic,body-centered cubic,and hexagonal close-packed metals during plastic forming and the mech-anism underlying ultrasonic vibration forming were reviewed.The main challenges and future research direction of the ultrasonic vibra-tion plastic forming of metals were also discussed.

关键词： ultrasonic vibration plastic forming crystal structure microstructure forming mechanism

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MoS2 nanoflowers and PEDOT:PSS nanocomposite enabling wearable dual-mode pressure sensors

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Science China Technological Sciences 2024年第6期67卷 1737-1747页

作者： WANG FengMing YANG WeiJia MA Ke SHEN GengZhe SU DaoJian LI BaiJun WANG ShuangPeng QIN BoLong ZHANG Chi XIN Yue CAO XiaoBing HE Xin School of Applied Physics and materials Wuyi University Biomaterials R&D Center Zhuhai Institute of Advanced TechnologyChinese Academy of Sciences Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials EngineeringUniversity of Macau

A versatile sensing platform employing inorganic MoS2nanoflowers and organic poly（3,4-ethylene dioxythiophene）: poly（styrene sulfonate）(PEDOT:PSS) has been investigated to develop the resistive and capacitive force-sensitive devices. The microstructure of the sensing layer heightens the sensitivity and response time of the dual-mode pressure sensors by augmenting electron pathways and inner stress in response to mechanical stimuli. Consequently, the capacitive and resistive sensors exhibit sensitivities of 0.37 and 0.12 kPa-1, respectively, while demonstrating a remarkable response time of approximately 100 ms.Furthermore, it is noteworthy that the PEDOT:PSS layer exhibits excellent adhesion to polydimethylsiloxane（PDMS） substrates, which contributes to the development of highly robust force-sensitive sensors capable of enduring more than 10000loading/unloading cycles. The combination of MoS2/PEDOT:PSS layers in these dual-mode sensors has shown promising results in detecting human joint movements and subtle physiological signals. Notably, the sensors have achieved a remarkable precision rate of 98% in identifying target objects. These outcomes underscore the significant potential of these sensors for integration into applications such as electronic skin and human-machine interaction.

关键词： MoS2/PEDOT:PSS nanocomposite force-sensitive sensor multi-scaled microstructure physiological signals monitoring object grasping recognition

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High-current pulsed electron beam modification on microstructure and performance of Cu/CuW diffusion bonding joints

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Rare Metals 2024年第6期43卷 2819-2831页

作者： Na-Na Tian Cong-Lin Zhang Peng Lyu Jin-Tong Guan Jie Cai Qing-Feng Guan Shun Guo School of materials Science and Engineering Jiangsu University School of Material Science and Engineering Yancheng Institute of Technology Engineering institute of advanced Manufacturing and Modern Equipment Technology Jiangsu University

This study investigates the influence of high-current pulsed electron beam（HCPEB） modification on the microstructure and shear strength of Cu/CuW joints.Reliable solid-state diffusion bonding of modified-Cu（MCu） and modified-CuW（M-CuW） was achieved by HCPEB modification pretreatment at a temperature of 800-900 ℃ and a pressure of 5 MPa for 10-50 min.Experiments demonstrate that HCPEB modification facilitates the dissolution of W and Cu,resulting in the formation of a Cu0.4W0.6solid solution and thus enhancing the uniform distribution of microstructures.Additionally,HCPEB-induced defects play a beneficial role in promoting the diffusion process by providing fast diffusion paths for elements.The optimal joints with the maximum shear strength of 213.7 MPa were obtained through bonding M-Cu and M-CuW at 900℃ and 5 MPa for 30 min,which attributes to the combined effects of fine-grained strengthening and solid solution strengthening.Overall,the application of HCPEB modification showcases its effectiveness in promoting element diffusion and enhancing the mechanical performance of the joints.

关键词： HCPEB Element diffusion Shear strength Crystal defects Surface modification

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