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Effect of Bath pH on the Squareness of Electroless CoNiWP Magnetic Films

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Journal of Materials Science & Technology 2008年第5期24卷 712-714页

作者： Haibin CHENG Shuai XU Wenyu ZHAO Suling ZHAO pengcheng zhai Zhigang SUNand Qingjie ZHANGt pengcheng zhai Zhigang SUN Qingjie ZHANG State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy, it has been found that the microstructure and the magnetic properties of films were influenced greatly by the bath pH. At the bath pH 8.06, the grain size and coercivity of the films reach maximuml while the squareness （Mr/Ms） of MH curves reaches minimum. The Henkel plots indicates that the exchange-coupling interaction is very weak at this pH, which may be caused by phase-separation and large grain size, and then results in the lowest squareness. At pH above 8.5, obvious exchange-coupling interaction is observed because of the inexistence of phase-separation and the refinement of grain size.

关键词： CoNiWP magnetic film Bath pH Squareness Exchange-coupling interaction

Shear Stress in MR Fluid with Small Shear Deformation in Bctlattic Structure

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Journal of Wuhan University of Technology(Materials Science) 2008年第4期23卷 532-535页

作者： LIU Lisheng RUAN Zhongwei zhai pengcheng ZHANG Qingjie State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

A theoretical model based on BCT lattice structure was developed. Resultant force in the BCT lattice structure was deduced, following the interaction force of two kinds of magnetic particles. According to empirical FroHlich-Kermelly law, the relationship between the magnetic induction and the magnetic field was discussed, and a predictive formula of shear stresses of the BCT lattice structure model was established for the case of small shear deformation. Compared with the experimental data for different particle volume fractions, the theoretical results of the shear stress indicate the effects of the saturation magnetization and the external magnetic field on the shear stress.

关键词： magnetorheological fluids (MR fluids) body-centered-tetragonal(BCT) interaction force shear stress small deformation

Shear induced deformation twinning evolution in thermoelectric InSb

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npj Computational Materials 2021年第1期7卷 1008-1016页

作者： Zhongtao Lu Ben Huang Guodong Li Xiaolian Zhang Qi An Bo Duan pengcheng zhai Qingjie Zhang William A.Goddard III Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhanPR China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhanPR China Department of Chemical and Materials Engineering University of Nevada RenoRenoNVUSA Materials and Process Simulation Center California Institute of TechnologyPasadenaCAUSA

Twin boundary(TB)engineering has been widely applied to enhance the strength and plasticity of metals and alloys,but is rarely adopted in thermoelectric(TE)*** previous first-principles results showed that nanotwins can strengthen TE Indium Antimony(InSb)through In–Sb covalent bond rearrangement at the ***,we further show that shear-induced deformation twinning enhances plasticity of *** demonstrate this by employing large-scale molecular dynamics(MD)to follow the shear stress response of flawless single-crystal InSb along various slip *** observed that the maximum shear strain for the (111)[112] slip system can be up to 0.85 due to shear-induced deformation *** attribute this deformation twinning to the“catching bond”involving breaking and re-formation of In–Sb bond in *** finding opens up a strategy to increase the plasticity of TE InSb by deformation twinning,which is expected to be implemented in other isotypicⅢ–V semiconductors with zinc blende structure.

关键词： deformation plasticity Shear

Dense dislocations induced ductile SnTe thermoelectric semiconductor over a wide range of temperatures

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Journal of Materials Science & Technology 2023年第13期144卷 213-218页

作者： Houjiang Yang Xiege Huang Bo Duan Luoqi Wu Hongtao Wang Xiaobin Feng Maoyuan Jiang Guodong Li Ling Zhou pengcheng zhai Qingjie Zhang Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Most inorganic thermoelectric semiconductors are intrinsically brittle,restricting the application of ther-moelectric ***,developing ductile thermoelectric materials is crucial to thermoelectric technology *** this work,single-phase SnTe bulks with dense dislocations were prepared by melting quenching combined with spark plasma *** resulting SnTe thermoelectric materials exhibited a large compressive strain of∼7.5%at room temperature,originating from high-density pre-existing mobile *** initiation of localized slip bands and preferred slip system were also identified by first-principles *** microstructural characterizations reveal that the thermal activated dislocation emission and migration lead to higher compressive strains at intermediate *** 673 K,the deformation mechanism changed from dislocation mediated to grain boundary mediated plasticity,resulting in an ultra-high compressive strain of∼42%.In sum,new insights into the mechanical behavior of SnTe thermoelectric material over a wide range of temperatures were *** work offers the dislocation engineering strategy to design ductile thermoelectric materials for flexi-ble electronics and energy systems.

关键词： SnTe Ductile thermoelectric materials Deformation mechanism Dislocation engineering

Intrinsic mechanical behavior of MgAgSb thermoelectric material:An ab initio study

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Journal of Materiomics 2020年第1期6卷 24-32页

作者： Guodong Li Qi An Umut Aydemir Sergey I.Morozov Bo Duan pengcheng zhai Qingjie Zhang William A.Goddard Ⅲ Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhan430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China Department of Chemical and Materials Engineering University of Nevada RenoRenoNV89557USA Department of Chemistry Koc UniversitySariyerIstanbul34450Turkey Boron and Advanced Materials Research Center Koc UniversitySariyerIstanbul34450Turkey Department of Computer Simulation and Nanotechnology South Ural State UniversityChelyabinsk454080Russia Materials and Process Simulation Center California Institute of TechnologyPasadenaCA91125USA

α-MgAgSb based thermoelectric(TE)device attracts much attention for its commercial application because it shows an extremely high conversion efficiency of ~8.5% under a temperature difference of 225 ***,the mechanical behavior of α-MgAgSb is another serious consideration for its engineering ***,we apply density functional theory(DFT)simulations to examine the intrinsic mechanical properties of all three MgAgSb phases,including elastic properties,shear-stress-shear-strain relationships,deformation and failure mechanism under ideal shear and biaxial shear *** find that the ideal shear strength of α-MgAgSb is 3.25 GPa along the most plausible(100)slip *** strength is higher than that of β-MgAgSb(0.80 GPa)and lower than that of γ-MgAgSb(3.43 GPa).The failure of α-MgAgSb arises from the stretching and breakage of MgeSb bond α-MgAgSb under pure shear load,while it arises from the softening of MgeAg bond and the breakage of AgeSb bond under biaxial shear *** suggests that the deformation mechanism changes significantly under different loading conditions.

关键词： MgAgSb thermoelectric materials Density functional theory Ideal strength Deformation mechanism

Ductile deformation mechanism in semiconductor α-Ag_(2)S

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npj Computational Materials 2018年第1期4卷 289-294页

作者： Guodong Li Qi An Sergey I.Morozov Bo Duan William A.Goddard III Qingjie Zhang pengcheng zhai G.Jeffrey Snyder State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology430070 WuhanChina Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA Department of Chemical and Materials Engineering University of Nevada RenoRenoNV 89557USA Department of Computer Simulation and Nanotechnology South Ural State UniversityChelyabinsk 454080Russia Materials and Process Simulation Center California Institute of TechnologyPasadenaCA 91125USA

Inorganic semiconductor α-Ag_(2)S exhibits a metal-like ductile behavior at room temperature,but the origin of this high ductility has not been fully explored *** on density function theory simulations on the intrinsic mechanical properties of α-Ag_(2)S,its underlying ductile mechanism is attributed to the following three factors:(i)the low ideal shear strength and multiple slip pathways under pressure,(ii)easy movement of Ag–S octagon framework without breaking Ag−S bonds,and(iii)a metallic Ag−Ag bond forms which suppresses the Ag-S frameworks from slipping and holds them *** easy slip pathways(or easy rearrangement of atoms without breaking bonds)in α-Ag_(2)S provide insight into the understanding of the plastic deformation mechanism of ductile semiconductor materials,which is beneficial for devising and developing flexible semiconductor materials and electronic devices.

关键词： deformation ductile ductility

Dual occupations of sulfur induced band flattening and chemical bond softening in p-type S_(y)Co_(4)Sb_(12-2y)S_(2y) skutterudites

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Journal of Materiomics 2022年第1期8卷 88-95页

作者： Jialiang Li Xiaolian Zhang Haoqin Ma Bo Duan Guodong Li Jiong Yang Hongtao Wang Houjiang Yang Ling Zhou pengcheng zhai Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of TechnologyWuhan430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China Materials Genome Institute Shanghai University99 Shangda RoadShanghai200444China

The electronegative filling in skutterudites not only broadened the scope of filling atoms,but also facilitated the preparation of p-type ***,the introduction of a single sulfur atom in the Co_(4)Sb_(12) cannot be achieved without charge compensation through the traditional equilibrium *** the present study,the dual occupations of S-atoms by self-charge compensation were shown as the most stable forms under high pressure,and a series of p-type S_(y)Co_(4)Sb_(12-2y)S_(2y) skutterudites was successfully prepared by high-pressure-high-temperature(HPHT)*** electronic structures and transport properties of as-obtained materials were investigated,and the related mechanisms were *** results suggested that the presence of S-impurities led to flattening of the electronic band that led to a higher Seebeck *** S-doped Co_(4)Sb_(12) displayed lower elastic modulus,elastic constant,and Debye temperature,thus indicating the chemical bond softening in *** thermal conductivities of S_(y)Co_(4)Sb_(12-2y)S_(2y) compounds reduced monotonously with the increase in *** study provides a new and promising avenue for optimizing the thermoelectric properties of p-type Co_(4)Sb_(12).

关键词： Electronegative filling skutterudites Self-charge compensation Band flattening Bond softening

Pressure induced convergence of conduction bands in Al doped Mg_(2)Si: Experiment and theory

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Journal of Materiomics 2019年第1期5卷 81-87页

作者： Jialiang Li Xiaolian Zhang Bo Duan Yunlong Cui Houjiang Yang Hongtao Wang Junchao Li Xiaojun Hu Gang Chen pengcheng zhai Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics Wuhan University of TechnologyWuhan430070China High Pressure High Temperature Institute of Physics Wuhan University of TechnologyWuhan430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan430070China

High-pressure and high-temperature(HPHT)synthesis provides an effective way to tune the band structure of materials and improve their electronic *** investigate the influence of synthesis pressure on electronic properties,Mg_(1.97)Al_(0.03)Si samples were synthesized using the HPHT *** maximum effective mass 0.92me is obtained for the sample prepared with the synthesis pressure of 3 GPa,leading to the biggest Seebeck coefficient201.3 mV/K at room ***,the 3 GPa sample obtains the higher electron carrier concentration and electrical conductivity,resulting in nearly overall enhancement of power *** Density Functional Theory(DFT)calculations evidences that the Conduction Bands Minimum(CBM)can be tuned effectively by applied pressure and the convergence of the CBM leads to a larger effective mass of DOS,which are beneficial to the enhancement of power *** results indicate that high-pressure is a powerful tool to tune Mg_(1.97)Al_(0.03)Si band structures.

关键词： Mg2Si High-pressure synthesis Band degeneracy Thermoelectric materials

The Mechanical Properties of Skutterudite CoAs_3 by Molecular Dynamics(MD) Simulation

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Journal of Wuhan University of Technology(Materials Science) 2008年第3期23卷 415-418页

作者：刘立胜翟鹏程 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Skutterudite CoAs3 is a potentially important thermoelectric material. Morse potential is employed here to carry out molecular dynamics simulations of nanobulk CoAs3 at the temperature of 0 K. The stress-strain relationships under uniaxial tensile and/or compressive strain are obtained. The elastic modulus, extreme strength and deformation mechanism are studied. The simulation results indicate that nanobulk CoAs3 abruptly ruptures at much higher strain level under tension than conventional bulk CoAs3. Both the extreme stresses under tension and compression are much higher than those of conventional bulk CoAs3.

关键词： Skutterudite thermoelectric molecular dynamics Morse potential