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Synergistic effect of bonding heterogeneity and phonon localization in introducing excellent thermoelectric properties in layered heteroanionic NdZnSbO material

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Journal of Energy Chemistry 2025年第01期 259-272页

作者： Da Wan Shuwei Tang Shulin Bai Xiaodong Li Peng Ai Wanrong Guo Tuo Zheng College of materials Science and engineering Liaoning Technical University faculty of Chemistry Northeast Normal University

Layered rare-earth metal oxides, harnessing the dual properties of oxides and two-dimensional layered materials, exhibit remarkable thermal stability and quantum confinement effects. Therefore, this work adopts the first-principles calculation combined with the Boltzmann transport theory to predict the thermoelectric properties of NdZnSbO compound. The coexistence of weak interlayer van der Waals interactions, robust intralayer ionic bonding, and partial covalent bonding leads to remarkable bonding heterogeneity, which engenders pronounced phonon scattering and imposes constraints on thermal transport along the out-of-plane direction. The weakened chemical bonds induced by the antibonding states, together with the rattling-like behavior of the Zn atom, culminate in the profound anharmonicity in the layered NdZnSbO compound. The weakening bond and heavy element contribute to the softness of phonon modes, which significantly diminishes the phonon group velocity. The redistribution-dominated four-phonon scattering process spans a large optical gap, which effectively reduces the lattice thermal conductivity. The NdZnSbO compound exhibits direct semiconductor characteristic with a bandgap of 0.73 e V by adopting the Heyd-Scuseria-Ernzerhof(HSE06) functional in combination with spin–orbit coupling(SOC) effect. The multi-valley feature of NdZnSbO compound augur favorably for band degeneracy, thus amplifying the power factor. Consequently, an optimal figure-of-merit(ZT) of 3.40 at 900 K is achieved for the n-type NdZnSbO compound. The present study delves deeply insights into the origins for the low thermal conductivity of NdZnSbO compound and proposes an optimization scheme to enhance overall thermoelectric performance.

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Modeling of the Prediction of Densification Behavior of Powder Metallurgy Al–Cu–Mg/B_4C Composites Using Artificial Neural Networks

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 182-195页

作者： Temel Varol Aykut Canakci Sukru Ozsahin Department of Metallurgical and materials engineering Engineering Faculty Karadeniz Technical University Department of Industrial engineering Engineering FacultyKaradeniz Technical University

Al-Cu-Mg/B4Cp metal matrix composites with reinforcement of up to 20 wt% were produced using the powder metallurgy technique. The effects of reinforcement ratio, reinforcement size, milling time, and compact pressure on the density and porosity of the composites reinforced with 0, 5, 10, and 20 wt% B4C particles were studied. Moreover, an artificial neural network model has been developed for the prediction of the effects of the manufacturing parameters on the density and porosity of powder metallurgy Al-Cu-Mg/B4Cp composites. This model can be used for predicting the densification behavior of Al-Cu-Mg/B4Cp composites produced under reinforcement of different sizes and amounts with various milling times and compact pressures. The mean absolute percentage error for the predicted values did not exceed 1.6%.

关键词： Al alloys Composite Mechanical milling Metal matrix composite Artificial neural network

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Unveiling the reaction products in heat treated Si3N4–Ti joined ceramics by transmission electron microscopy

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Journal of Advanced Ceramics 2019年第4期8卷 500-508页

作者： Orkun TUNCKAN Hilmi YURDAKUL Servet TURAN faculty of Aeronautics and Astronautics Eskisehir Technical University Rafet Kayis faculty of engineering Department of Metallurgical and Materials EngineeringAlanya Alaaddin Keykubat University faculty of engineering Department of Materials Science and EngineeringEskisehir Technical University

Joining is a crucial process for the production of complex-shaped advanced engineering *** understanding of ceramic–metal interfaces during joining or following heat-treatment steps is therefore of important concern in designing the new *** discharge joining(CDJ)method was firstly carried out to compose the ceramic–metal joint material by silicon nitride(Si3N4)–titanium(Ti)***,heat treatment was performed on the Si3N4-Ti joints in air atmosphere at 1000℃temperature to reveal the interface reactions and *** layer that occurred between the Si3N4 and Ti interfaces and new phase formations were examined by transmission electron microscopy(TEM)-based various imaging and chemical analysis *** transparent samples for TEM characterization were prepared by focused ion beam(FIB)milling and lifting *** on the detailed TEM results,Si and N diffusion arising from the Si3N4 ceramic was observed towards Ti metal foil side and further interacted with Ti *** upshot of current diffusion was that Ti3N2 reaction layer with 50 nm thickness was formed at the interface while titanium silicon nitride(Ti6Si3N)matrix phase including dendritic-shaped Ti2 N grains occurred in the Ti *** is believed that our TEM-based microscopy results not only provide the knowledge on ceramic–metal joint materials by CDJ method,but also contribute new insights on the development of various new joint systems.

关键词： capacitor discharge joining(CDJ) Si3N4 Ti transmission electron microscopy(TEM)

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Effects of nanosized metallic palladium loading and calcination on characteristics of composite silica

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中国有色金属学会会刊：英文版 2003年第6期13卷 1394-1400页

作者：吴玉程吴侠李广海张立德 faculty of materials science and engineering Institute of Solid State physics

In order to investigate the effects of nanosized metallic palladium loading and calcination on the characteristics of composite silica, the silica was prepared by sol-gel technique, leading to an amorphous solid with mesoporosity, and the pore size distribution is narrow, centered at 35 nm. The composite silica was formed by impregnating palladium precursor into the porous network with sequel calcination in hydrogen. The results show that the nanosized palladium as guest phase in the composite silica is subjected to the mesoporous structure and calcination, resulting in the changes of optical adsorption that red-shifted to higher wavelength with the palladium loading and the heating temperature. The tailoring of the optical properties can be ascribed to the effect of the nanosized metal particles and interactions occurred between palladium and silica.

关键词：二氧化硅钯纳米材料复合材料煅烧加载

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An experimental investigation of properties of polyethylene reinforced with Al powders

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Journal of Zhejiang University-Science A(Applied physics & engineering) 2011年第8期12卷 583-592页

作者： Victoria CHIFOR Zafer TEKINER Mehmet TURKER Radu ORBAN Department of materials Science and Technology Faculty of Materials Science and EngineeringTechnical University of Cluj-Napoca Mechanical/Metallurgy Education Department Faculty of Technical EducationGazi University

Mechanical and physical properties, such as tensile strength, elongation at break, modulus of elasticity, Shore D hardness, melt flow rate (MFR), and electrical and thermal conductivities of composites with high density polyethylene matrix reinforced with Al powders were investigated experimentally. Measurements of the mechanical and physical properties were performed up to a reinforcing component concentration of 30% volume Al powder and compared with mathematical models from the literature. The obtained results have shown that experimental data were in good agreement with theoretical data. The ultimate tensile strength (UTS) and elongation at break decreased with increasing Al powder content, which was attributed to the intro-duction of discontinuities in the polymer structure, and modulus of elasticity increased with increasing Al content. The composite preparation conditions allowed the formation of a random distribution of metallic particles in the polymer matrix volume for system high density polyethylene-Al (HDPE-Al). There was a cluster formation of Al particles at higher Al contents in the polymer matrix. Electrical and thermal conductivity values of HDPE-Al composites were higher than pure HDPE values.

关键词： Polymer composite Mechanical properties Melt flow rate(MFR) Thermal conductivity Electrical conductivity

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A New Probe: AFM Measurements for Random Disorder Systems

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Chinese physics Letters 2019年第1期36卷 5-9页

作者： R.Salci D.A.Acar O.Oztirpan M.Ramazanoglu physics engineering Department Istanbul Technical University Brockhouse Institute for materials Research

We study the quenched random disorder(QRD) effects created by aerosil dispersion in the octylcyanobiphenyl(8CB) liquid crystal(LC) using atomic force microscopy technique. Gelation process in the 8CB+aerosil gels yields a QRD network which also changes the surface topography. By increasing the aerosil concentration, the original smooth pattern of LC sample surfaces is suppressed by the emergence of a fractal aerosil surface effect and these surfaces become more porous, rougher and they have more and larger crevices. The dispersed aerosil also serves as pinning centers for the liquid crystal molecules. It is observed that via the diffusion-limitedaggregation process, aerosil nano-particles yield a fractal-like surface pattern for the less disordered samples. As the aerosil dispersion increases, the surface can be described by more aggregated regions, which also introduces more roughness. Using this fact, we show that there is a net correlation between the short-range ordered x-ray peak widths(the results of previous x-ray diffraction experiments) and the calculated surface roughness. In other words, we show that these QRD gels can also be characterized by their surface roughness values.

关键词： Random Disorder Systems AFM measurement QRD

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Magnetization of Gd diffused YBa_2Cu_3O_(7-x) superconductor:Experiment and theory

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Chinese physics B 2013年第7期22卷 489-493页

作者： F. Inanir S. Yildiz K. Ozturk S. Celebi Department of physics Art and Science FacultyRecep Tayyip Erdogan University Department of Metallurgical and materials engineering Ahi Evran University Department of physics Karadeniz Technical University

The magnetization of Gd diffused YBa2Cu3O7-x is measured by a vibrating sample magnetometer （VSM） at selected temperatures （5, 25, 50, 77 K）. The experimental results for the magnetization are analyzed in the critical state framework involving Kim-Anderson field dependence Jc（H）=Jc0/（1＋｜H｜/H0）n of critical current density and equilibrium magnetization M eq . It is found that the inclusion of the equilibrium magnetization becomes more important at higher temperatures. At 77 K, the shape of the isothermal M-H hysteresis curve is governed by the equilibrium magnetization. Some superconducting parameters are determined by fitting the calculated curves to the experimental data.

关键词： type-II superconductor YBCO surface effect equilibrium magnetization critical-state model

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Effect of Primary and Eutectic Mg_2Si Crystal Modifications on the Mechanical Properties and Sliding Wear Behaviour of an Al–20Mg_2Si–2Cu–xBi Composite

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Journal of materials Science & Technology 2016年第11期32卷 1083-1097页

作者： Saeed Farahany Hamidreza Ghandvar Nur Azmah Nordin Ali Ourdjini Mohd Hasbullah Idris Department of materials and Mechanical engineering Buein Zahra Technical University Department of materials Manufacturing and Industrial Engineering Faculty of Mechanical Engineering Universiti Teknologi Malaysia (UTM) Department of Mechanical engineering Faculty of Engineering University of Ottawa

This work investigated the microstructure evolution, tensile, impact, hardness, and sliding wear properties of an Al–20Mg2Si–2Cu in situ composite treated with different Bi contents. The desired modification of primary Mg2 Si particles was achieved with the addition of 0.4 wt% Bi. Increasing Bi beyond 0.4 wt%resulted in a loss of modification, possibly due to the formation of Al8 MgB iS i4 compound before the precipitation of the primary Mg2 Si. Additionally, the structure of the pseudo-eutectic Mg2 Si was transformed from plate to fibrous, which was consistent with decrease of growth temperature extracted from the cooling curve thermal analysis. Addition of Bi had an effect on the morphology of Al5 Fe Si（β）, Al2Cu（θ） and Al5Cu2Mg8Si6（Q） intermetallic compounds. The tensile strength, elongation percentage, impact toughness, and hardness increased by 6%, 13%, 75%, and 23%, respectively, due to modification of both the primary and eutectic Mg2 Si crystals. The tensile and impact fracture surfaces showed fewer decohered particles in the Bi-treated composite. The enhancement in wear resistance of the Bi-treated composite could be attributed to solid lubricant function of insoluble soft Bi phase and modification effects on Mg2 Si particles.

关键词： Al–Mg2Si Composite Modification Bismuth Mechanical properties Wear

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Investigation on microwave heating for direct leaching of chalcopyrite ores and concentrates

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International Journal of Minerals,Metallurgy and materials 2013年第3期20卷 228-233页

作者： Kubra Onol Muhlis Nezihi Saridede Department of Metallurgical and materials engineering Faculty of Chemistry & Metallurgy Yildiz Technical University Davutpasa Campus

The use of microwave energy in materials processing is a relatively new development presenting numerous ad- vantages because of the rapid heating feature. Microwave technology has great potential to improve the extraction efficiency of metals in terms of both a reduction in required leaching time and an increase in the recovery of valuable metals. This method is especially pertinent in view of the increased demand for environment-friendly processes. In the present study, the influence of microwave heating on the direct leaching of chalcopyrite ores and concentrates were investigated. The results of microwave leaching experiments were compared with those obtained under conventional conditions. During these processes, parameters such as leaching media, temperature, and time have been worked to determine the optimum conditions for proper copper dissolution. Experimental results show that microwave leaching is more efficient than conventional leaching. The optimum leaching conditions for microwave leaching are the solid-to-liquid ratio of 1：100 g/mL, the temperature of 140℃, the solution of 0.5 M H2SOa- 0.05 M Fe：（SOa）a, and the time of I h.

关键词： hydrometallurgy chalcopyrite leaching microwave heating

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Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

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International Journal of Minerals,Metallurgy and materials 2016年第11期23卷 1315-1322页

作者： Gheorghe Gurau Carmela Gurau Vedamanickam Sampath Leandru Gheorghe Bujoreanu faculty of engineering "Dun?rea de Jos" University of Galati Department of Metallurgical and materials engineering Indian Institute of Technology Madras faculty of materials Science and engineering "Gheorghe Asachi" Technical University of Ia?i

Low-cost iron-based shape memory alloys（SMAs） show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure torsion（HSHPT） process on the microstructural evolution of an Fe–Mn–Si–Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations characteristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence of ε-martensite with an HCP crystal structure and γ-phase with an FCC structure.

关键词： iorn manganese silicon alloys shape memory effect nanostructured materials martensite plastic deformation

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