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Ball Milling Synthesis and Property of Nd_(0.7)Sr_(0.3)MnO_3 Manganites

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Journal of Materials Science & Technology 2010年第8期26卷 721-724页

作者： Shunsheng Chen Changping Yang Lingfang Xu shaolong tang The Provincial Key Laboratory of Piezoelectric Ceramics Materials and Apparatus Faculty of Physics and Electronic Technology Hubei University Wuhan 430062 China Department of Physics Nanjing University Nanjing 210093 China

Strontium doped perovskite-type Nd0.7Sr0.3MnO3 ceramics were synthesized completely by high-energy ball milling raw oxides of Nd2O3, SrCO3 and MnO2. The optimal ball milling time and mass ratio of milling balls to raw materials are 4 h and 10：1, respectively. The grain size of as-milled Nd0.7Sr0.3MnO3 ceramics ranges from 51 to 93 nm, and the fine particles contain two phases of crystalline phase and amorphous phase. For the Nd0.7r0.3MnO3 synthesized by ball milling and sequent heat treatment, a remarkable colossal electroresistance （CER） effect is observed and the CER ratio reaches 900% at Curie temperature Tc when the load voltage increases from 0.1 to 0.8 V.

关键词： High-energy ball milling Perovskite structure Colossal electroresistance (CER) Microstructure defect

Li adsorption on monolayer and bilayer MoS_2 as an ideal substrate for hydrogen storage

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Chinese Physics B 2018年第6期27卷 320-328页

作者： Cheng Zhang shaolong tang Mingsen Deng Youwei Du School of Physics and Electronic Science Guizhou Normal University Guiyang 550001 China Department of Physics Nanjing University Nanjing 210093 China Guizhou Provincial Key Laboratory of Computational Nano-material Science Guizhou Education University Guiyang 550018 China

Based on the first-principles plane wave calculations, we show that Li adsorbed on monolayer and bilayer MoS2 forming a uniform and stable coverage can serve as a high-capacity hydrogen storage medium, and Li-coated MoS2 can be recycled by operations at room temperature due to Li having strength binding, big separation and is stable against clustering. The full Li coverage MoS2 system（2 ＊ 2 hexagonal MoS2 supercell） can reach up to eight H2 molecules on every side, corresponding to the gravimetric density of hydrogen storage up to 4.8 wt% and 2.5 wt% in monolayer and bilayer MoS2, respectively. The adsorption energies of hydrogen molecules are in the range of 0.10 e V/H2–0.25 e V/H2,which are acceptable for reversible H2 adsorption/desorption near ambient temperature. In addition, compared with light metals decorated low dimension carbon-based materials, the sandwiched structure of MoS2 exhibits the greatly enhanced binding stability of Li atoms as well as slightly decreased Li-Li interaction and thus avoids the problem of metal *** is interesting to note that the Li atom apart from the electrostatic interaction, acts as a bridge of hybridization between the S atoms of MoS2 and adsorbed H2 molecules. The encouraging results show that such light metals decorated with MoS2 have great potential in developing high performance hydrogen storage materials.

关键词： MoS2 Li anchoring hydrogen storage first-principles

Metamaterial electromagnetic wave absorbers and devices:Design and 3D microarchitecture

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Journal of Materials Science & Technology 2022年第13期108卷 90-101页

作者： Qianqian Huang Gehuan Wang Ming Zhou Jing Zheng shaolong tang Guangbin Ji College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Chemistry and Materials Science College of ScienceNanjing Forestry UniversityNanjing 210037China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

Metamaterials refer to a class of artificial composite structures with supernormal physical properties that natural materials do not *** emergence of metamaterials has opened up new research directions for classical electromagnetic theory and made it possible to manipulate electromagnetic waves *** of most important applications of metamaterials is metamaterial absorbers(MMAs).The properties of MMAs depend on the material composition,cell size and structure,which could often achieve"perfect"absorption through reasonable *** review starts with the development of MMAs and describes the status of this absorber,then mainly focuses on bionic design and new artificial ***,it is to draw inspiration from natural plants and animals,design novel structures to get better absorbing ***,the artificial design can achieve the optimize absorption capacity as well as absorption ***’s more,this review summarizes the 3D printing technology to prepare MMAs that are different from traditional printed circuit board *** MMAs produced by 3D printing technology can prepare more complex shapes,and has light weight and better absorbing properties.

关键词： Electromagnetic waves absorption Metamaterial Bionic design Artificial design 3D printing

The dielectric behavior and efficient microwave absorption of doped nanoscale LaMnO_(3)at elevated temperature

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Nano Research 2022年第8期15卷 7731-7741页

作者： Zhigang Mu Guoke Wei Hang Zhang Lu Gao Yue Zhao shaolong tang Guangbin Ji College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Aviation Key Laboratory of Science and Technology on Advanced Surface Engineering AVIC Manufacturing Technology InstituteBeijing 100024China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

LaMnO_(3)perovskite has great potential in microwave absorption at high temperature due to its complex doping effect and super *** current research mainly focuses on the doping ratio regulation,while the mechanism of doping effect at high temperature is still lack of sufficient *** this work,La1−xSrxMn1−yFeyO_(3)(LaMnO_(3),La_(0.7)Sr_(0.3)MnO_(3),and La_(0.7)Sr_(0.3)Mn_(0.8)Fe_(0.2)O_(3))nanostructures with different doping sites were successfully prepared by the solid phase reaction ***,the high temperature dielectric test samples were obtained by mixing with cordierite(2MgO·2Al_(2)O_(3)·5SiO_(2)(MAS)).The results showed that the temperature dependence of Mn ion spin state had a significant impact on the high temperature dielectric behavior of La_(1−x)Sr_(x)Mn_(1−y)FeyO_(3).Particularly,when the thickness is only 1.9 mm,La_(0.7)Sr_(0.3)Mn_(0.8)Fe_(0.2)O_(3)/MAS can achieve the widest bandwidth of 4.2 GHz covered the entire X-band(8.2–12.4 GHz)and a minimum reflection loss(RL)value of−17.99 dB at 500℃.In order to improve the operating temperature of La_(0.7)Sr_(0.3)Mn_(0.8)Fe_(0.2)O_(3)/MAS,a cellular array structure was designed by using computer simulation technology(CST)software to introduce magnetic *** the outer length of the hexagon is 1 mm and the coating thickness is 1.9 mm,the widest bandwidth covers the X-band and the minimum RL value is−15.35 dB at 800℃.Therefore,La_(0.7)Sr_(0.3)Mn_(0.8)Fe_(0.2)O_(3)has a great prospect as an efficient high temperature microwave absorber.

关键词： microwave absorption doping perovskite high temperature dielectric behavior

Characterization of transient groundwater flow through a high arch dam foundation during reservoir impounding

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第4期8卷 462-471页

作者： Yifeng Chen Jiamin Hong shaolong tang Chuangbing Zhou State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072 China School of Civil Engineering and Architecture Nanchang University Nanchang 330031 China

Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in situ stress, such as rockburst, spalling, damage of deep surrounding rocks, and timedependent damage, were observed during construction of these projects. To address these problems, the dynamic design method for deep hard rock tunnels is proposed based on the disintegration process of surrounding rocks using associated dynamic control theories and technologies. Seven steps are basically employed：（i） determination of design objective,（ii） characteristics of site, rock mass and project, and identification of constraint conditions,（iii） selection or development of global design strategy,（iv）determination of modeling method and software,（v） preliminary design,（vi） comprehensive integrated method and dynamic feedback analysis, and（vii） final design. This dynamic method was applied to the construction of the headrace tunnels at Jinping II hydropower station. The key technical issues encountered during the construction of deep hard rock tunnels, such as in situ stress distribution along the tunnels, mechanical properties and constitutive model of deep hard rocks, determination of mechanical parameters of surrounding rocks, stability evaluation of surrounding rocks, and optimization design of rock support and lining, have been adequately addressed. The proposed method and its application can provide guidance for deep underground projects characterized with similar geological conditions.

关键词： Deep hard rock tunnels Dynamic design method Rockburst In situ stress Constitutive model

Effects of manganese substitution on magnetic and magnetostrictive properties of Tb_(0.5)Dy_(0.5)(Fe_(1-x)Mn_(x))_(1.92)/epoxy composites with spherical single-crystal particles

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Journal of Rare Earths 2023年第8期41卷 1211-1216,I0004页

作者： Dashun Dong Geng Wei Jin Qian Ye Huang Li Zhang Hehe Ding Yangguang Shi shaolong tang Jiangsu Key Laboratory for Nanotechnology Collaborative Innovation Center of Advanced MicrostructuresNational Laboratory of Solid State MicrostructuresDepartment of PhysicsNanjing UniversityNanjing 210093China Key Laboratory of Aerospace Information Materials and Physics(MIIT) Department of Applied PhysicsNanjing University of Aeronautics and AstronauticsNanjing 210016China

Spherical Tb_(0.5)Dy_(0.5)(Fe_(1-x)Mn_(x))_(1.92)(x=0,0.05,0.10 and 0.15)single-crystal particles were *** magnetic anisotropy of the alloy decreases as x increases from 0 to ***,we prepared giant magnetostrictive composites with these spherical Tb_(0.5)Dy_(0.5)(Fe_(1-x)Mn_(x))_(1.92)single-crystal *** a consequence,well-orie nted Tb_(0.5)Dy_(0.5)(Fe_(1-x)Mn_(x))_(1.92)composites with 55 vol%Tb_(0.5)Dy_(0.5)(Fe_(1-x)Mn_(x))_(1.92)particles were *** Tb_(0.5)Dy_(0.5)(Fe_(0.9)Mn_(0.1))_(2)composite manifests a good low-field magnetostrictive property and saturation magnetostriction at an axial pressure of 10 MPa,λ_(‖,saturation)≈2100 ppm,which is larger than that of the commercially available Terfenol-D(1400-1800 ppm).The preparation of composites with single crystal spherical powders may be an effective solution of developing high-performance magnetostrictive composites.

关键词： Tb-Dy-Fe-Mn Spherical single-crystal powder Magnetostriction Magnetostrictive composites Rare earths

Broadband absorption of macro pyramid structure based flame retardant absorbers

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Journal of Materials Science & Technology 2022年第33期128卷 228-238页

作者： Hengda Sun Ying Zhang Yue Wu Yue Zhao Ming Zhou Lie Liu shaolong tang Guangbin Ji College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China General Test Systems Inc. Shenzhen 518102China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China

Flame-retardant materials with good electromagnetic wave absorption play an increasingly important role in Over-the-Air(OTA)tests in microwave anechoic *** this work,carbon nanotubes and ammonium polyphosphate(CNTs@APP)composite were prepared by crosslinking with the silane coupling agent(KH550).The flame retardancy is improved with the increase of ***,the microwave absorption performance(MAP)and processing difficulty changed greatly as ***,magnesium aluminum double-layer metal hydroxide(LDH)was obtained by coprecipitation method and processing into the coating,so as to realize flame retardancy which reaches the limiting oxygen index(LOI)of 24.8%and good MAP at the same ***,a high-frequency structure simulator(HFSS^(TM))was used to simulate the pyramid model to realize the broadband absorption,and the optimal parameter range was obtained,that is,when the total height of the material is 40 mm,the height of the base accounts for 1/5-1/3,and the tangent of the half top angle is near 1/5,which result in the best ***,the broadband absorption of 14.36 GHz(3.64-18 GHz)was realized when the base height is 1/3,and the broadband absorption of 14 GHz(4-18 GHz)can be realized under the condition of large-angle oblique incidence of 0°-60°.

关键词： Electromagnetic wave absorption Broad bandwidth Pyramid structure Flame retardant HFSS^(TM)

The point defect and electronic structure of K doped LaCo_(0.9)Fe_(0.1)O_(3)perovskite with enhanced microwave absorbing ability

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Nano Research 2022年第4期15卷 3720-3728页

作者： Fan Wang Weihua Gu Jiabin Chen Yue Wu Ming Zhou shaolong tang Xingzhong Cao Peng Zhang Guangbin Ji College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China National Laboratory of Solid State Microstructures Nanjing UniversityNanjing 210093China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

ABO_(3)perovskites,owning unique properties,have great research prospect in electromagnetic wave absorption ***,doping can significantly regulate the dielectric loss,whereas the magnetic loss can be *** this work,the crystal structure and electromagnetic properties can be regulated systematically by the K,Fe co-doping for LaCoO_(3)perovskites(LKCFO)under the condition of fixed F *** addition,the obtained samples show the obvious interfacial polarization effect on accounting to the small size effect,which is conducive to the effective microwave *** analyzing the evolution of the positron annihilation lifetime and the first-principles calculation of the oxygen density of states for the series of LKCFO perovskites,it is found that the charge transport characteristics will be controlled by the point defect generated by allelic *** point defect content decreases and then increases as the doping level *** prepared perovskite exhibits the lowest defect density and the largest dielectric loss capability,which indicates that the lower point defects promote electron migration and thus enhance the dielectric loss;thus,the electromagnetic wave absorption bandwidth up to 6.2 GHz is *** contrast,both insufficient and excessive K doping are detrimental to the enhancement of microwave ***,the practical application value was investigated using Computer Simulation Technology(CST)*** LKCFO-2 exhibits the smallest RCS value(below-10 dBm^(2))at almost-90°-90°with a thickness of 2 mm,providing an effective method for study excellent microwave absorption and scattering property.

关键词： microwave absorption perovskites doping effective bandwidth point defect

The newsvendor model revisited： the impacts of high unit holding costs on the accuracy of the classic model

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Frontiers of Business Research in China 2018年第2期12卷 141-154页

作者： shaolong tang Stella Cho Jacqueline Wenjie Wang Hong Yan Division of Business and Management Beijing NormalUniversity-Hong Kong Baptist University United International College 2000 JinTong RoadTangjiawan Zhuhai Guangdong China

The newsvendor problem has been applied in various business settings. It is often assumed that the decision variable, i.e., order-up-to level, has no impacts on the holding costs for average inventory cycled in a given period, which is the difference between beginning and ending inventory levels on hand in that period. The average holding cost for this portion of inventory is conveniently and approximately calcutated as half the product of the unit holding cost and the expectation of the demand in one period if it is assumed that the inventory is approximately evenly consumed. It is a good approximation when the unit holding cost is significantly lower than the unit backorder cost as this optimal solution to inventory level is able to guarantee a low probability of understocking. However, if this condition does not hold, the approximation may deviate from the actual cost and cannot measure the expected holding cost for this portion of inventory. This paper examines the impact of the cycle stock holding cost on the newsvendor model and the conditions under which this portion of cost is not negligible.

关键词： Newsvendor model Inventory control Stochastic model