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2020

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Articles 1 - 30 of 207

Full-Text Articles in Physical Sciences and Mathematics

Treated Hfo2 Based Rram Devices With Ru, Tan, Tin As Top Electrode For In-Memory Computing Hardware, Yuvraj Dineshkumar Patel Dec 2020

Treated Hfo2 Based Rram Devices With Ru, Tan, Tin As Top Electrode For In-Memory Computing Hardware, Yuvraj Dineshkumar Patel

Theses

The scalability and power efficiency of the conventional CMOS technology is steadily coming to a halt due to increasing problems and challenges in fabrication technology. Many non-volatile memory devices have emerged recently to meet the scaling challenges. Memory devices such as RRAMs or ReRAM (Resistive Random-Access Memory) have proved to be a promising candidate for analog in memory computing applications related to inference and learning in artificial intelligence. A RRAM cell has a MIM (Metal insulator metal) structure that exhibits reversible resistive switching on application of positive or negative voltage. But detailed studies on the power consumption, repeatability and retention …

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Effect Of Stereotaxically-Constructed Graphene On The Negative Electrode Performance Of Lead-Acid Batteries, Pin-Song Chen, Yi-Tao Hu, Xin-Yi Zhang, Pei-Kang Shen Dec 2020

Effect Of Stereotaxically-Constructed Graphene On The Negative Electrode Performance Of Lead-Acid Batteries, Pin-Song Chen, Yi-Tao Hu, Xin-Yi Zhang, Pei-Kang Shen

Journal of Electrochemistry

With the advantages of high ratio surface area, excellent conductivity and high stability, the stereotaxically-constructed graphene (SCG) material was added to the negative active material (NAM) of lead-acid battery for improving battery performance. XRD, SEM and cyclic voltammetry tests were carried out to analyze the influence of SCG on negative active material. It is found that the conversion efficiency of lead sulfate to lead in the negative active material added with SCG material was higher than that of control group, and the particle size of the lead sulfate obtained after the discharge reaction was smaller, which are favorable factors for …

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Preparations And Photoelectrochemical Performances Of Rgo-Tio2 Nanotubes Arrays, Ze-Yang Zhang, Lan Sun, Chang-Jian Lin Dec 2020

Preparations And Photoelectrochemical Performances Of Rgo-Tio2 Nanotubes Arrays, Ze-Yang Zhang, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Decorating TiO2 nanotube arrays with RGO to improve the photocatalytic activity of TiO2 nanotube arrays has been reported. For the reported RGO-TiO2 nanotube arrays, TiO2 nanotube arrays were prepared by anodizing the high-purity Ti foil in an organic electrolyte for multiple-step treatments, while RGO were deposited on TiO2 nanotube arrays by using cyclic voltammetry or other electrical reduction methods. To enhance the reduction degree and the coverage of RGO on the resultant RGO-TiO2 nanotube arrays, in this work, the one-step electrochemical anodization in hydrofluoric acid was used to fabricate TiO2 nanotube arrays with …

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Numerical Simulations Of Current And Temperature Distribution Of Symmetrical Double-Cathode Solid Oxide Fuel Cell Stacks Based On The Theory Of Electric-Chemical-Thermal Coupling, Cheng-Rong Yu, Jian-Guo Zhu, Cong-Ying Jiang, Yu-Chen Gu, Ye-Xin Zhou, Zhuo-Bin Li, Rong-Min Wu, Zheng Zhong, Wan-Bing Guan Dec 2020

Numerical Simulations Of Current And Temperature Distribution Of Symmetrical Double-Cathode Solid Oxide Fuel Cell Stacks Based On The Theory Of Electric-Chemical-Thermal Coupling, Cheng-Rong Yu, Jian-Guo Zhu, Cong-Ying Jiang, Yu-Chen Gu, Ye-Xin Zhou, Zhuo-Bin Li, Rong-Min Wu, Zheng Zhong, Wan-Bing Guan

Journal of Electrochemistry

Solid oxide fuel cell (SOFC) is a high-efficient clean conversion device for future energy management. Because of the low antioxidant reduction ability and complex thermal stress, the structure of traditional asymmetrical thin anode-supported planar SOFC is easily to be broken under stack operating conditions. To overcome these defects, a new complete symmetrical SOFC based on double-sided cathodes was developed. To study the influences of gas flow direction and current collection mode on the cell performance inside stack, a numerical model was established by finite element method based on the theory of electro-thermo-chemo multiphysical coupling. By applying this model, the molar …

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Pitting Behaviors Of Passivated And Trans-Passivated 304 Stainless Steel, Jing Shen, Zi-Ming Wang, Da-Jiang Zheng, Guang-Ling Song Dec 2020

Pitting Behaviors Of Passivated And Trans-Passivated 304 Stainless Steel, Jing Shen, Zi-Ming Wang, Da-Jiang Zheng, Guang-Ling Song

Journal of Electrochemistry

In order to further understand the passivation and trans-passivation behaviors of 304 stainless steels, the samples were pretreated under different polarization potentials and their corrosion behaviors were investigated. It was found that the pitting potential of the untreated sample was the same as that of the sample treated with 1.1 V trans-passivation potential, while the pitting potential of the sample treated with 0.5 V passivation treatment was the highest. This observation was further verified by the SKP results. According to SEM observations, the surface of the untreated sample preserved a polishing morphology, while the surface of the 0.5 V passivation …

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Degradation And Thermal Characteristics Of Lini0.8Co0.15Al0.05O2/Graphite Lithium Ion Battery After Different State Of Charge Ranges Cycling, Cun Wang, Wei-Jiang Zhang, Teng-Fei He, Bo Lei, You-Jie Shi, Yao-Dong Zheng, Wei-Lin Luo, Fang-Ming Jiang Dec 2020

Degradation And Thermal Characteristics Of Lini0.8Co0.15Al0.05O2/Graphite Lithium Ion Battery After Different State Of Charge Ranges Cycling, Cun Wang, Wei-Jiang Zhang, Teng-Fei He, Bo Lei, You-Jie Shi, Yao-Dong Zheng, Wei-Lin Luo, Fang-Ming Jiang

Journal of Electrochemistry

The LiNi0.8Co0.15Al0.05O2 (NCA) cathode exhibits high energy density and large reversible capacity, which plays an essential role in the field of electric vehicles (EVs). However, low capacity retention and poor thermal stability limit its application. Few literatures are found for the capacity degradation mechanism of NCA/graphite batteries at home and abroad. The different state of charge (SOC) ranges cycle degradation behaviors of 18650-type NCA/graphite (2.4 Ah) battery were studied in this paper. The SOC ranges considered were 0% ~ 20% (low), 20% ~ 70% (medium), 70% ~ 100% (high), and 0% ~ 100% …

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Preparations And Sodium Storage Properties Of Ni3S2@Cnt Composite, Ming-Tao Duan, Yan-Shuang Meng, Hong-Shuai Zhang Dec 2020

Preparations And Sodium Storage Properties Of Ni3S2@Cnt Composite, Ming-Tao Duan, Yan-Shuang Meng, Hong-Shuai Zhang

Journal of Electrochemistry

Transition metal sulfides (TMSs)-based electrode materials with highly reversible sodium storage have attracted extensive attentions as one of the most prospective electrode materials for sodium ion batteries (SIBs). However, low cycling stability and rate property caused by large volume expansion and poor electronic conductivity during the electrochemical reaction still hamper their further practical application. In this work, in-situ encapsulated Ni3S2 nanoparticles in carbon nanotubes (Ni3S2@CNT) have been successfully fabricated as an anode material for high-performance SIBs by a one-step solid-phase calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), …

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Core-Shell Structured Ru@Ptru Nanoflower Electrocatalysts Toward Alkaline Hydrogen Evolution Reaction, Xue-Liang Wang, Yuan-Yuan Cong, Chen-Xi Qiu, Sheng-Jie Wang, Jia-Qi Qin, Yu-Jiang Song Dec 2020

Core-Shell Structured Ru@Ptru Nanoflower Electrocatalysts Toward Alkaline Hydrogen Evolution Reaction, Xue-Liang Wang, Yuan-Yuan Cong, Chen-Xi Qiu, Sheng-Jie Wang, Jia-Qi Qin, Yu-Jiang Song

Journal of Electrochemistry

Water electrolysis for hydrogen production is beneficial for solving the problem of energy crisis and environmental issues. It is necessary to study highly active and cost-effective catalysts toward hydrogen evolution reaction (HER) to reduce the consumption of noble metals. Herein, we report the synthesis of core-shell structured Ru@Pt0.24Ru nanoflowers electrocatalyst by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol at 160 oC. The average diameter of the resultant Ru@Pt0.24Ru was 16.5±4.0 nm with a bulk atomic ratio between Pt and Ru of 0.24:1 and a surface ratio of 3.3:1 …

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Effect Of Reaction Conditions On Cu⁃Catalyzed Co2 Electroreduction, Chang Zhu, Wei Chen, Yan-Fang Song, Xiao Dong, Gui-Hua Li, Wei Wei, Yu-Han Sun Dec 2020

Effect Of Reaction Conditions On Cu⁃Catalyzed Co2 Electroreduction, Chang Zhu, Wei Chen, Yan-Fang Song, Xiao Dong, Gui-Hua Li, Wei Wei, Yu-Han Sun

Journal of Electrochemistry

Electrochemical conversion of carbon dioxide (CO2) driven by renewable electricity that can meet both carbon emission reduction and renewable energy utilization has been rapidly developed in recent years. Copper (Cu) catalyst has long been a promising candidate for CO2 electroreduction applications because of its natural abundance and specific capability of producing a substantial amount of C2 products. However, various metallic Cu electrodes reported have been significantly influenced by the adsorption of certain cation/anion ions, resulting in wide-span catalytic activities and selectivity for various products. In addition, a recent report demonstrated that by virtue of gas-diffusion flow cell …

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Preparation And Process Optimization Of Cathode Materials For Lithium-Sulfur Batteries, Kai Wu Dec 2020

Preparation And Process Optimization Of Cathode Materials For Lithium-Sulfur Batteries, Kai Wu

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries represent promising candidates for next-generation energy storage system due to their high energy density and low material cost. However, the industrial application of Li-S batteries remains challenges because of the shuttle effect from lithium polysulfides and the lack of facial routes for Li-S battery preparation. To solve these problems, a cathode consisting of different commercial carbon materials, namely, acetylene black (SP), Ketjen Black (KB) and carbon nanotube (CNT), with sulfur (S) is prepared separately for Li-S battery. After the process of 8-h ball milling for KB/S composite, together with the polyvinyl pyrrolidone (PVP) binder, the cathode could …

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Effect Of 18-Crown-6 Additive On Chromium Electrodeposition In Ionic Liquid, Yi-Jie Wang, Dong-Fang Niu, Xin-Sheng Zhang Dec 2020

Effect Of 18-Crown-6 Additive On Chromium Electrodeposition In Ionic Liquid, Yi-Jie Wang, Dong-Fang Niu, Xin-Sheng Zhang

Journal of Electrochemistry

Trivalent chromium ion (Cr3+) is used for electrodeposition due to its low toxicity. Electrodeposition in ionic liquids can greatly solve for hydrogen evolution problem. However,as a widely used Cr(III) precursor, chromium chloride hydrate (CrCl3·6H2O), still contains water. In the presence of water, Cr3+ will form a complex coordination structure with water molecules ([Cr(H2O)6]3+), which is a stable octahedral structure and is difficult to be directly reduced to chromium metal. Therefore, coordination agents should be added into the bath. In this work, the effect of 18-Crown-6 additive on chromium electrodeposition was investigated in …

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Synergistic Effect Of Dissolving O2 And Wavelength On The Photo-Assisted Anodic Deposition Of Ceo2 Thin Films, Tong-Zheng Jin, Yu-Meng Yang, Sheng-Hui Fan, Guo-Ying Wei, Zhao Zhang Dec 2020

Synergistic Effect Of Dissolving O2 And Wavelength On The Photo-Assisted Anodic Deposition Of Ceo2 Thin Films, Tong-Zheng Jin, Yu-Meng Yang, Sheng-Hui Fan, Guo-Ying Wei, Zhao Zhang

Journal of Electrochemistry

Cerium dioxide (CeO2) thin films have been applied as new material in many technical fields such as solid oxide fuel cells, catalysts, UV absorbents, pharmacology, and coatings for corrosion protection of many metals and alloys. Electrodeposition is widely considered to be one of the best preparation methods for CeO2 film. In this work, the CeO2 films were prepared by photo-assisted anodic deposition in the bath solutions containing 0.05 mol·L-1 cerium (III) nitrate, 0.1 mol·L-1 ammonia acetate and 70% (V/V) ethanol onto 316L stainless steel (SS) surface. The synergistic effects of three monochromatic …

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Preparations And Properties Of Low Cost Sulfide Solid Electrolytes Li6-XPs5-XClX, Na-Chuan Yang, Yu Wang, Yi Shuai, Kang-Hua Chen Dec 2020

Preparations And Properties Of Low Cost Sulfide Solid Electrolytes Li6-XPs5-XClX, Na-Chuan Yang, Yu Wang, Yi Shuai, Kang-Hua Chen

Journal of Electrochemistry

With the shortage of energy and environmental pollution, the storage of electric energy is getting more attention all over the world. In order to improve the energy density and safety performance of batteries, uses of solid electrolyte become more and more popular. However, because the conductivity of solid electrolyte is not comparable to that of liquid electrolyte, the solid electrolyte application has certain limitations. With the efforts of researchers from various countries, there are several different solid electrolytes having better conductivity, for instance, sulfide solid electrolyte and oxide solid electrolyte. Sulfide solid electrolyte is a highly promising solid electrolyte material …

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Step-By-Step Modification Of Graphite Felt Electrode For Vanadium Redox Flow Battery, Jing-Yuan Lou, Dong-Jiang You, Xue-Jing Li Dec 2020

Step-By-Step Modification Of Graphite Felt Electrode For Vanadium Redox Flow Battery, Jing-Yuan Lou, Dong-Jiang You, Xue-Jing Li

Journal of Electrochemistry

As a well-known electrode material of the vanadium redox flow battery (VRFB),graphite felt electrode is the frequently-used electrode material in VRFB, and its low electrochemical activity is one of the key factors for the low power density of VRFB. In this work, we proposed a step-by-step modification method, which used KMnO4 to oxidize graphite felt first and then placed in an activation solution to excite its reactivity, to improve the electrochemical performance of the graphite felt electrode. According to the results from cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) characterizations …

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Neutron Pick-Up Reactions In 18o (10 Mev/Nucleon) + Ta, S. Lukyanov, T. Issatayev, B. M. Hue, V. Maslov, K. Mendibayev, S. S. Stukalov, D. Aznabayev, A. Shakhov, K. A. Kuterbekov, A. M. Kabyshev Dec 2020

Neutron Pick-Up Reactions In 18o (10 Mev/Nucleon) + Ta, S. Lukyanov, T. Issatayev, B. M. Hue, V. Maslov, K. Mendibayev, S. S. Stukalov, D. Aznabayev, A. Shakhov, K. A. Kuterbekov, A. M. Kabyshev

Eurasian Journal of Physics and Functional Materials

The availability of new radioactive ion beams has broadened the study of nuclear reactions and nuclear structure. The main mechanism to produce the secondary beams is the fragmentation of the projectile. An alternative method for the production of the exotic nuclei is the multinucleon transfer. We measured production cross section for the B, C, N and O isotopes in the reaction18O + Ta and the beam energy at 10 MeV/nucleon. The cross sections were obtained by integrating the momentum distributions of the isotopes. It was shown that in deep inelastic processes the production yields of different isotopes could …

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Determination Of The Response Function Of The Nai Detector For Γ-Quanta With An Energy Of 4.43 Mev, Formed During Inelastic Scattering Of Neutrons With An Energy Of 14.1 Mev On Carbon Nuclei, S. B. Dabylova, Yu. N. Kopach, S. K. Sakhiyev, D. N. Grozdanov, N. A. Fedorov Dec 2020

Determination Of The Response Function Of The Nai Detector For Γ-Quanta With An Energy Of 4.43 Mev, Formed During Inelastic Scattering Of Neutrons With An Energy Of 14.1 Mev On Carbon Nuclei, S. B. Dabylova, Yu. N. Kopach, S. K. Sakhiyev, D. N. Grozdanov, N. A. Fedorov

Eurasian Journal of Physics and Functional Materials

The work is devoted to determining the response function of the detector NaI(Tl) for γ-quanta with energy of 4.43 MeV, formed during inelastic scattering of neutrons with energy of 14.1 MeV on the nuclei 12 C. In gamma spectrometry, output pulses are recorded, the amplitudes of which are proportional to the energy lost in the detection medium by incident photons. One of the main tasks of radiation detection is to restore radiation characteristics from signals measured at the outputs of detectors. For this, it is necessary to know, first of all, the general characteristics of detectors as converters of radiation …

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Influence Of Electrolytic-Plasma Hardening Modes On Structure And Hardness Of 0.34cr-1ni-Mo-Fe Steel, B. K. Rakhadilov, Z. A. Satbayeva, R. S. Kozhanova, D. R. Baizhan, M. K. Rakhadilov, G. B. Botabayeva Dec 2020

Influence Of Electrolytic-Plasma Hardening Modes On Structure And Hardness Of 0.34cr-1ni-Mo-Fe Steel, B. K. Rakhadilov, Z. A. Satbayeva, R. S. Kozhanova, D. R. Baizhan, M. K. Rakhadilov, G. B. Botabayeva

Eurasian Journal of Physics and Functional Materials

The article presents the results of studying the process of electrolytic-plasma hardening of 0.34Cr-1NiMo- Fe steel by surface hardening, as well as the results of the current-voltage characteristics of the cathodic electrolytic-plasma process depending on the composition of the electrolyte. Temperature-time and special modes of electrolytic-plasma hardening of steel 0.34Cr-1Ni-Mo-Fe were determined. The optimal composition of the electrolyte for electrolytic-plasma hardening has been determined, providing a relatively high heating rate and high hardness of the steel surface. It has been determined that after the electrolytic-plasma hardening, the microhardness of 34KhN1M steel increases 2.9 times due to the formation of fine …

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Study Of The Influence Of The Phase Composition And Crystal Structure Of Fexni100-X Nanostructures On The Efficiency Of Using Lithium Ion Batteries As Anode Materials, D. B. Borgekov, N. A. Hlebnikov, D. I. Shlimas, A. L. Kozlovskiy Dec 2020

Study Of The Influence Of The Phase Composition And Crystal Structure Of Fexni100-X Nanostructures On The Efficiency Of Using Lithium Ion Batteries As Anode Materials, D. B. Borgekov, N. A. Hlebnikov, D. I. Shlimas, A. L. Kozlovskiy

Eurasian Journal of Physics and Functional Materials

The results of the efficiency of using Fe x Ni 100��x nanotubes as anode materials for lithium-ion batteries have been obtained. In the course of research, it was found that an increase in the concentration of nickel in the structure to 40 and 60 at.% leads to a sharp increase in the resource number of cycles by more than two times in comparison with iron nanotubes. Such a difference in the resource lifetime is due to the higher stability of Fe x Ni 100��x nanotubes with a nickel concentration of more than 40 at.% to destruction, as well as resistance …

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Determination Of Radon Levels In Dwellings And Social Objects And Evaluation Annual Effective Dose From Inhalation Of Radon In Stepnogorsk Area Northern Kazakhstan, D. S. Ibrayeva, M. N. Aumalikova, K. B. Ilbekova, M. M. Bakhtin, P. K. Kazymbet Dec 2020

Determination Of Radon Levels In Dwellings And Social Objects And Evaluation Annual Effective Dose From Inhalation Of Radon In Stepnogorsk Area Northern Kazakhstan, D. S. Ibrayeva, M. N. Aumalikova, K. B. Ilbekova, M. M. Bakhtin, P. K. Kazymbet

Eurasian Journal of Physics and Functional Materials

Radon is a noble gas that is one of the natural radioactive decay products of radium resulting from the disintegration of uranium. Humans are exposed to sources of natural radiation activity, being radon and its progeny breathing air responsible for more than 50% of the annual dose received from natural radiation. The aim of this study was to determine the radon concentration in the air in settlements’ dwellings and social objects and calculate the annual effective dose of population from radon on the territory mining activities in Stepnogorsk area. The study has shown that activity concentrations of indoor radon in …

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Assessment Of The Dose Burden And Health Status Of The Uranium Processing Workers Of The Republic Of Kazakhstan, M. N. Aumalikova, D. S. Ibrayeva, K. Ilbekova, P. K. Kazymbet, M. M. Bakhtin, D. D. Janabaev, N. Z. Altaeva Dec 2020

Assessment Of The Dose Burden And Health Status Of The Uranium Processing Workers Of The Republic Of Kazakhstan, M. N. Aumalikova, D. S. Ibrayeva, K. Ilbekova, P. K. Kazymbet, M. M. Bakhtin, D. D. Janabaev, N. Z. Altaeva

Eurasian Journal of Physics and Functional Materials

The main objective of current study is to assess the dose burden and health status of workers at the uranium processing hydrometallurgical plant in order to develop measures aimed at reducing their incidence. This article presents the results of radiation monitoring and data on the health status of workers at the hydrometallurgical plant of the Stepnogorsk Mining and Chemical Combine (SMCC). The data of the accumulated effective dose for the entire length of service, as well as data on the incidence rate for the period 2013-2019, obtained from the base of the Industrial Radiation and Epidemiological Register, have been analyzed. …

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Changes In The Structure And Properties Of Zro2 Detonation Coatings During Annealing, B. K. Rakhadilov, D. N. Kakimzhanov, G. Botabaeva, D. B. Buitkenov, N. Kantai, L. B. Bayatanova Dec 2020

Changes In The Structure And Properties Of Zro2 Detonation Coatings During Annealing, B. K. Rakhadilov, D. N. Kakimzhanov, G. Botabaeva, D. B. Buitkenov, N. Kantai, L. B. Bayatanova

Eurasian Journal of Physics and Functional Materials

The article studied the effect of annealing on the structure and properties of zirconium dioxide coatings obtained by detonation spraying. Detonation spraying was realized on a computerized detonation spray ing complex of the new generation CCDS2000. Determined that coatings made of zirconium dioxide are characterized by high adhesive strength of adherence to the substrate. Thermal annealing of coated samples was performed at temperatures of 900-1200◦C. It was determined that the microhardness of zir conium dioxide coatings increases by 10-25% depending on the annealing temperature after annealing. The results of nanoindentation showed that the nanohardness of the coatings after …

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Investigation Of The Applicability Of Post-Irradiation Annealing To Reduce The Degree Of Disorder In Aln Ceramic To Proton Irradiation, A. L. Kozlovskiy Dec 2020

Investigation Of The Applicability Of Post-Irradiation Annealing To Reduce The Degree Of Disorder In Aln Ceramic To Proton Irradiation, A. L. Kozlovskiy

Eurasian Journal of Physics and Functional Materials

The work presents study results of the applicability of high-temperature heat treatment (500-700°C) of nitride ceramics irradiated with protons with an energy of 1.5 MeV and a dose of 10 16 cm ��2 . It was found that heat treatment for 60 minutes at a temperature of 700°C allows us to significantly reduce the density of radiation-induced defects and distortions in ceramics structure due to partial annihilation and relaxation of point defects. Dependences of changes in the strength and mechanical characteristics of ceramics on the temperature of post-irradiation annealing are shown. Based on the data obtained, a conclusion was made …

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Theory And Improved Methods For Probing The Cavitation To Fracture Transition, Christopher Barney Dec 2020

Theory And Improved Methods For Probing The Cavitation To Fracture Transition, Christopher Barney

Doctoral Dissertations

A material is considered soft when its bulk modulus is significantly greater than its shear modulus. Rubbery polymers are a class of soft materials where resistance to extension is mainly entropic in nature. Polymeric soft solids differ from liquids due to the presence of a percolated network of strong bonds that resist deformation and flow on a given time scale. The incompressible nature, entropically driven elasticity, and molecular scale network structure of soft polymeric solids combine to impart unique mechanical behavior that often results in complex material responses to simple loading situations. An important example of this is cavitation in …

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Thermo-Fluid Characterizations Of The Powder-Bed Fusion Additive Manufacturing Processes Using Laser And Electron Beam, M Shafiqur Rahman Dec 2020

Thermo-Fluid Characterizations Of The Powder-Bed Fusion Additive Manufacturing Processes Using Laser And Electron Beam, M Shafiqur Rahman

University of New Orleans Theses and Dissertations

The powder-bed fusion (PBF) process is a subdivision of Additive Manufacturing (AM) technology where a heat source at a controlled speed selectively fuses regions of a powder-bed material to form three-dimensional (3-D) parts. Two of the most effective PBF processes are selective laser melting (SLM) and electron beam additive manufacturing (EBAM), which can fabricate full-density metallic parts in a layer-by-layer fashion. In this study, thermal behavior and melt-pool dynamics in the PBF process are investigated by developing 3-D multiphysics-based thermo-fluid models for both SLM and EBAM, containing Ti-6Al-4V alloy as a powder-bed material. The laser and electron beams are modeled …

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Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li Dec 2020

Two New Finite Element Schemes And Their Analysis For Modeling Of Wave Propagation In Graphene, Jichun Li

Mathematical Sciences Faculty Research

© 2020 The Author(s) In this paper, we investigate a system of governing equations for modeling wave propagation in graphene. Compared to our previous work (Yang et al., 2020), here we re-investigate the governing equations by eliminating two auxiliary unknowns from the original model. A totally new stability for the model is established for the first time. Since the finite element scheme proposed in Yang et al. (2020) is only first order in time, here we propose two new schemes with second order convergence in time for the simplified modeling equations. Discrete stabilities inheriting exactly the same form as the …

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Effect Of Citric Acid On Slump, Compressive Strength, And Setting Time Of Belitic Calcium Sulfoaluminate Concrete, Israel Aguilar Rosero Dec 2020

Effect Of Citric Acid On Slump, Compressive Strength, And Setting Time Of Belitic Calcium Sulfoaluminate Concrete, Israel Aguilar Rosero

Graduate Theses and Dissertations

Belitic calcium sulfoaluminate (BCSA) cement has well established advantages related to fast setting time, fast strength gain, long-term strengths, shrinkage, and sustainability. Due to its fast setting and hardening, this type of cement has historically been used to repair concrete structures, highways, and runways. This work provides much needed guidance on establishing mix design criteria for BCSA cement. Guidance is also given on the effects of set retarders on strength, slump, and setting times. Citric acid and a phosphonic acid-based admixture were tested as retarders for different concrete mixtures. Three studies were performed. In the slump study five different water …

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Ultrafast Spin-Currents And Charge Conversion At 3d-5d Interfaces Probed By Time-Domain Terahertz Spectroscopy, T. H. Dang, J. Hawecker, E. Rongione, G. Baez Flores, D. Q. To, J. C. Rojas-Sanchez, H. Nong, J. Mangeney, J. Tignon, F. Godel, S. Collin, P. Seneor, M. Bibes, A. Fert, M. Anane, J. M. George, L. Vila, M. Cosset-Cheneau, D. Dolfi, R. Lebrun, P. Bortolotti, Kirill Belashchenko, S. Dhillon, H. Jaffrès Dec 2020

Ultrafast Spin-Currents And Charge Conversion At 3d-5d Interfaces Probed By Time-Domain Terahertz Spectroscopy, T. H. Dang, J. Hawecker, E. Rongione, G. Baez Flores, D. Q. To, J. C. Rojas-Sanchez, H. Nong, J. Mangeney, J. Tignon, F. Godel, S. Collin, P. Seneor, M. Bibes, A. Fert, M. Anane, J. M. George, L. Vila, M. Cosset-Cheneau, D. Dolfi, R. Lebrun, P. Bortolotti, Kirill Belashchenko, S. Dhillon, H. Jaffrès

Kirill Belashchenko Publications

Spintronic structures are extensively investigated for their spin-orbit torque properties, required for magnetic commutation functionalities. Current progress in these materials is dependent on the interface engineering for the optimization of spin transmission. Here, we advance the analysis of ultrafast spin-charge conversion phenomena at ferromagnetic-Transition metal interfaces due to their inverse spin-Hall effect properties. In particular, the intrinsic inverse spin-Hall effect of Pt-based systems and extrinsic inverse spin-Hall effect of Au:W and Au:Ta in NiFe/Au:(W,Ta) bilayers are investigated. The spin-charge conversion is probed by complementary techniques-ultrafast THz time-domain spectroscopy in the dynamic regime for THz pulse emission and ferromagnetic resonance spin-pumping …

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Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek Dec 2020

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH4 that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH4 in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO2, which energetically takes place of the …

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Synthesis, Characterization, Spectroscopic, And Mesomorphic Studies Of New Schiff Base Ligands And Titanium, Cobalt, Nickel And Copper Metal Centers, Raj K. Gurung Dec 2020

Synthesis, Characterization, Spectroscopic, And Mesomorphic Studies Of New Schiff Base Ligands And Titanium, Cobalt, Nickel And Copper Metal Centers, Raj K. Gurung

Chemistry & Biochemistry Theses & Dissertations

Transition metal complexes with Schiff base ligands offer a wide application in the field of development of catalysis and material. The straightforward synthesis allowed the structural modification and helped to optimize in various application of such complexes. Titanium-containing complexes have been reported to be important for their catalytic and material applications through the coordination of a tetradentate Schiff base ligand, viz. N, N’-ethylene bis(salicylideneiminate) dianion (salen). Studies reporting the characterization of achiral titanium(IV) salen complexes are scarce due to their intricate nature. Such complexes would be comparatively less expensive and easier to prepare synthetically and thus could represent an …

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Static And Dynamical Properties Of Multiferroics, Sayed Omid Sayedaghaee Dec 2020

Static And Dynamical Properties Of Multiferroics, Sayed Omid Sayedaghaee

Graduate Theses and Dissertations

Since the silicon industrial revolution in the 1950s, a lot of effort was dedicated to the research and development activities focused on material and solid-state sciences. As a result, several cutting-edge technologies are emerging including the applications of functional materials in the design and enhancement of novel devices such as sensors, highly capable data storage media, actuators, transducers, and several other types of electronic tools. In the last two decades, a class of functional materials known as multiferroics has captured significant attention because of providing a huge potential for new designs due to possessing multiple ferroic order parameters at the …

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