Atomic Method Research Articles

Study of the features of determination of heavy metals in bottom sediments

In the work with the application of the atomic absorption method, the peculiarities of the influence of sample preparation on the degree of extraction of heavy metals in samples of bottom sediments were analyzed. Acid, acid-microwave sample preparation and their variations were used in the study. It was found that the greatest influence of the type of sample preparation on the degree of extraction is observed for iron and manganese. For zinc, the smallest dependence of the type of sample preparation on the completeness of its extraction from bottom sediments was noted. There is an ambiguous influence of the type of sample preparation on the degree of extraction for cobalt, copper and nickel, which may be related to the peculiarities of the chemical composition of the bottom sediments.

High activity retention Al–Bi–Zn-base composite powder with mild hydrogen generation

Al–10Bi–7Zn and Al–10Bi–7Zn–1.5X (X: Cu, Fe, Ni, in wt.%) composite powders were designed and prepared through phase diagram calculation and gas atomization method. The effects of Cu, Fe, and Ni on the hydrolysis of Al–Bi–Zn-base composite powders for hydrogen production were investigated respectively. The composition and morphology of powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS) analyses. Hydrolysis performance test results indicate that the additions of Cu, Fe, or Ni can modify the hydrogen production rate and enhance oxidation resistance in Al–10Bi–7Zn ternary alloy composite powder. In the quaternary composite powder system, Al–10Bi–7Zn–1.5Ni (wt.%) exhibits the best performance with the hydrogen generation yield of 75.3% (954.1 mL/g) within 500 min when reacting with distilled water at 60 °C and maintains a hydrogen yield of 57.9% (733.7 mL/g) within 1500 min after being stored (30 °C, relative humidity of 60%) for 7 d. In addition, the mechanism investigation suggested that the additions of Cu, Fe, or Ni in Al–Bi–Zn-base composite powders can stabilize the Al matrix to retain the high activity of powders resulting from inhibiting the cracking of composite powders in the air.

A GIS-based analysis of heavy metals around Otukpo rice mill in Benue state

Heavy metals are primarily sourced from natural pedo-geochemical backgrounds and anthropogenic occurrences like composting, sewage sludge, aerosol deposition, and waste animal manure. The study aims to determine the heavy metals within the rice mill in Otukpo to understand the spatial distribution with the objectives to examine the heavy metals within the identified activity areas in the Otukpo rice mill, to determine the spatial distribution of heavy metals within the study area and to compare heavy metal values with the acceptable limits. Soil samples were collected from ten locations at Otukpo Rice Mill to analyze heavy metal concentrations. The samples were collected using sterile bottles and a stainless trowel, and the soil samples were analyzed for the concentrations of Cadmium, Copper, Lead, Nickel, Zinc, Mercury, Iron, Arsenic, and Chromium using the Atomic Absorption Spectrophotometry method. The result was analyzed using interpolation to see the variation of the Heavy metals within the various activity areas. The result of the study reveals that Iron has the highest concentration at the Entrance point and lowest at the Generator house with a range value of 3.92 – 1.12mg/kg respectively. The highest concentration of Zinc was recorded at the Mechanic workshop while the lowest is at the Drying point with a range value of 0.135 – 0.872mg/kg respectively. The Husk dumpsite recorded the highest concentration of Copper (0.666mg/kg) with the Drying point recording the least (0.088 mg/kg). The study reveals uneven concentrations and highlights the effectiveness of the Geographic Information System in mapping heavy metal concentrations.

Isolation, and selection of indigenous potassium solubilizing bacteria from Vietnam Mekong Delta rhizospheric soils and their effects on diverse cropping systems

Potassium (K) is an essential nutrient for plant growth, biosynthesis, and metabolism. It enhances plant tolerance to salinity and acidity by triggering various defense mechanisms. These characteristics are particularly important to agricultural production in the Vietnam Mekong River Delta, experiencing increased saltwater intrusion, precipitation extremes and unpredictable drought. This study isolated and selected indigenous potassium-solubilizing bacteria (PSB) from Vietnam Mekong Delta rhizospheric soils collected from three different ecological systems producing rice, maize, kumquat, and green onion. Experiments were conducted to evaluate the effect of indigenous PSB on rice seedlings and future potential as biostimulants for commercial field application. To isolate PSB, solid Aleksandrov medium supplemented with 0.2% muscovite was used. The soluble K was quantified using the atomic absorption method at a wavelength of 766.5 nm. Among 24 isolates, Burkholderia vietnamiensis L1.1 and Staphylococcus hominis T7.3 exhibited the highest K solubilization, releasing 567 μg L−1 and 488 μg L−1 liquid medium, respectively. The study explored the optimal conditions for K release, revealing that a temperature of 35 °C, a pH 5, and NaCl concentration up to 1 % in a medium favored K solubilization. B. vietnamiensis L1.1 significantly enhanced rice seed germination (95.3 %) compared to the control treatment without PSB (82 %). Furthermore, the combined application of B. vietnamiensis L1.1 and S. hominis T7.3 notably improved rice growth under K deficient conditions. This research suggests that these indigenous PSB can effectively increase plant available K and improve the productivity of rice and other crops grown under saline and acidic stresses.

PHYSICOCHEMICAL AND HEAVY METAL CONTENT ASSESSMENT OF WATER QUALITY IN KEANA AND NASARAWA–EGGON LOCAL GOVERNMENT AREAS, NASARAWA STATE, NIGERIA

This study conducted a thorough evaluation of the physicochemical parameters of various drinking water sources in Keana and Nasarawa Eggon, Nasarawa State. The assessment involved the use of standard methods to analyze the water samples. Additionally, the heavy metal contents were determined using the atomic absorption spectrophotometric method. The findings revealed that the pH levels ranged from 7.36 to 8.16 in Keana (KN) and 5.70 to 5.80 in Nasarawa Eggon (NE), with mean pH values of 7.74 and 5.74, respectively. The conductivity varied from 3.94 to 4.56 µS/cm in KN and 510 to 1760 µS/cm in NE. Alkalinity content ranged from 4.06 to 4.52 mgL-1 in KN and 45 to 50 mgL-1 in NE. Nitrate, acidity, chloride, phosphate, TDS, DO, and BOD levels were also assessed. The metal concentrations included Pb, Mn, Cr, Zn, Fe and Cu, and were within permissible limits, except for Pb and Ni, which exceeded WHO specifications. This study provides crucial insights into the water quality of these regions, essential for ensuring the safety of water for human consumption and other activities.

Experimental investigation on detonation characteristics of boron-rich gelled propellant in static premixed combustible gases

A detonation in multiphase air-kerosene-boron mixtures is studied experimentally and the initiation and propagation characteristics of multiphase pulse detonation are emphasized. The boron-rich kerosene gelled propellants are taken as the fuel to analyze its detonation characteristics in static premixed combustible gases. The factors affecting detonation initiation including component, atomization, and ignition method of propellant are elucidated respectively. Considering atomization, evaporation and combustion, a small molecular organic compound is employed to fabricate metallized gelled propellants enriched with substantial boron particles. The dynamic atomization of gelled propellant with varying boron content is imaged by means of visual observation devices, and the ejecting parameters are optimized properly from actual initiation conditions. A flame jet by hot turbulent jet is applied to amplify the ignition energy of deflagration to detonation transition in boron-rich gelled propellant, which has not been seen ever. Results show that the ignition energy is positively correlated with initial pressure formed by combustible gas products. The multiphase detonation wave of boron-rich gelled propellant is successfully induced by premixed H2/O2 mixtures, and its detonation propagation characteristic is closely associated with the increase of initial pressure of premixed gas and mass mixing ratio of working medium. The pressure peak and propagation velocity of detonation wave show a considerable improvement with increasing initial pressure of premixed combustible gas and mass mixing ratio, and the highest values can reach up to 8.65 MPa and 2750 m/s respectively.

Strain rate-dependent tensile deformation and failure behavior in single-crystal β-Sn

Given that electronic components often undergo intricate thermal and mechanical loads during operation, comprehensively understanding lead-free solder, particularly solder based on [Formula: see text]-Sn, in various complex load conditions, plays a crucial role in ensuring the structural integrity and functional reliability of integrated circuits. Therefore, investigating the mechanical properties and fracture behavior of [Formula: see text]-Sn as a solder material holds paramount importance. In this study, we performed molecular dynamics simulations using the modified embedded atom method to investigate the mechanical properties and crack propagation of single-crystal [Formula: see text]-Sn under different strain rates. The research findings demonstrate that as the strain rate increases, the single-crystal [Formula: see text]-Sn exhibits elevated yield strength, fracture strength, and strain, while the elastic modulus decreases. Under higher strain rates, the relationship between dislocation density and strain rate in single-crystal [Formula: see text]-Sn is quantitatively elucidated. The substantial increase in internal dislocation density imparts conspicuous strain hardening to the material, rendering plastic deformation more challenging. This observation sheds light on the microscale mechanism of strain hardening at the atomic level. Our results shall facilitate a deeper investigation into the mechanical behavior of single-crystal [Formula: see text]-Sn while also paving the path for optimizing the design and application of lead-free solder materials in the electronics industry.

Ultra strong FCC structured Ni8Cr4Co4Fe6W2 high entropy alloys with high strength and ductility by laser powder bed fusion

The high entropy alloys (HEAs) are widely used in high temperature service environment (such as aviation engine blades) with bright application potential in additive manufacturing. Laser powder bed fusion (LPBF) is technology currently offers the best reproducibility and dimensional accuracy for part production. The unique atomic lattice structure of HEA makes its plastic deformation mechanism different from that of traditional dilution alloy, resulting in the strengthening effect of face-centered cubic high-entropy alloy different from that of traditional metal alloy materials. In this paper, Ni8Cr4Co4Fe6W2 was designed by means of composition control. Its spherical powders with uniform composition were successfully prepared by high temperature remelting spheroidization (PHTR) method, compared with gas atomization (GA) method. The strain rate sensitivity m values of GA-Selective Laser Melting and PHTR-Selective Laser Melting samples were 0.030 and 0.027, respectively. The hardness of Ni8Cr4Co4Fe6W2 high-entropy alloy showed a trend of continuous increase with the decrease of grain size, while the elastic modulus didn’t change much (PHTR-SLM is 193 Gpa and GA-SLM is 189 Gpa). The simulated value of the contact stress decreased by 23 % compared with the theoretical value. The contact radius increased with the increase of plastic deformation in addition to the reduction of contact pressure. The printing sample value of the elongation, yield strength (YS) and Ultimate Tensile Strength (UTS) on PHTR-SLM has increased by 39.6 %, 33.7 % and 25.9 %, respectively in additive manufacturing, compared to GA-SLM. The ability to produce refractory HEAs through PHTR method will make it possible to manufacture complex geometry shapes at a reasonable cost.

Atomistic investigation of effect of alloying on mechanical properties and microstructural evolution of ternary FeCo-X (X = V, Nb, Mo, W)

This atomistic simulation study delves into the impact of V, Nb, Mo, and W on the mechanical properties of equiatomic FeCo, employing the modified embedded atom method (MEAM). An analysis of individual effects on antiphase boundary (APB) energies reveals a consistent reduction along preferred slip planes, except for Nb. Monte Carlo-molecular dynamics (MC-MD) simulations were used to explore the diffusion behavior of these solutes, highlighting their dynamic interactions and preference to migrate into the grain boundaries (GB).Tensile simulations conducted on nanocrystalline (NC) models oriented in different directions unveil comparable stress–strain curves, displaying continuous yielding with a humpy yield curve that varies with the straining orientation. Notably, W emerged as the most effective addition enhancing the ultimate tensile strength (UTS). Microcrack nucleation development differ depending on the straining direction. In binary FeCo and in the alloy with Mo additions, void development was observed at grain boundary (GB) triple junctions, while with V and W additions, it occurred at the intersection of a slip band and a GB, with limited propagation in both scenarios. In contrast, Nb additions show enhanced stress accommodation through slip band formation within grains, preventing microcrack development. These discoveries offer valuable insights on the impact of alloying elements on the mechanical behavior of ternary FeCo-X (X = V, Nb, Mo, W) alloys.

Emerging Non-Noble-Metal Atomic Layer Deposited Copper as Seeds for Electroless Copper Deposition.

Copper metal catalyst seeds have recently triggered much research interest for the development of low-cost and high-performance metallic catalysts with industrial applications. Herein, we present metallic Cu catalyst seeds deposited by an atomic layer deposition method on polymer substrates. The atomic layer deposited Cu (ALD-Cu) can ideally substitute noble metals Ag, Au, and Pd to catalyze Cu electroless deposition. The optimized deposition temperature and growth cycles of an ALD-Cu catalyzed seed layer have been obtained to achieve a flexible printed circuit (FPC) with a high performance electroless plating deposited Cu (ELD-Cu) film. The ELD-Cu films on the ALD-Cu catalyst seeds grown display a uniform and dense deposition with a low resistivity of 1.74 μΩ·cm, even in the through via and trench of substates. Furthermore, the ALD-Cu-catalyzed ELD-Cu circuits and LED devices fabricated on treated PI also demonstrate excellent conductive and mechanical features. The remarkable conductive and mechanical characteristics of the ALD-Cu seed catalyzed ELD-Cu process demonstrate its tremendous potential in high-density integrated FPC applications.

Surface atom knockout for the active site exposure of alloy catalyst

The fine regulation of catalysts by the atomic-level removal of inactive atoms can promote the active site exposure for performance enhancement, whereas suffering from the difficulty in controllably removing atoms using current micro/nano-scale material fabrication technologies. Here, we developed a surface atom knockout method to promote the active site exposure in an alloy catalyst. Taking Cu3Pd alloy as an example, it refers to assemble a battery using Cu3Pd and Zn as cathode and anode, the charge process of which proceeds at about 1.1 V, equal to the theoretical potential difference between Cu2+/Cu and Zn2+/Zn, suggesting the electricity-driven dissolution of Cu atoms. The precise knockout of Cu atoms is confirmed by the linear relationship between the amount of the removed Cu atoms and the battery cumulative specific capacity, which is attributed to the inherent atom-electron-capacity correspondence. We observed the surface atom knockout process at different stages and studied the evolution of the chemical environment. The alloy catalyst achieves a higher current density for oxygen reduction reaction compared to the original alloy and Pt/C. This work provides an atomic fabrication method for material synthesis and regulation toward the wide applications in catalysis, energy, and others.

ANALYSIS OF MERCURY (HG) CONTENT IN URINE AND ITS IMPACT ON HEALTH DISORDERS OF ILLEGAL GOLD MINING WORKERS IN MALOMBA VILLAGE, DONDO SUB-DISTRICT, TOLITOLI DISTRICT

Mercury is a heavy metal element that very easily enters the bodies of living creatures and joins the food chain. The living creatures most likely to be directly exposed to mercury are traditional miners who use the amalgam method to extract gold ore. The danger of poisoning posed by mercury for humans can be diagnosed through analysis of mercury levels in urine. Furthermore, this research aims to determine mercury levels in the urine of gold mine workers and to obtain information regarding the mercury content in the urine and the health problems of gold mine workers. The method used in this research was the calibration curve method with Cold Vapor Atomic Absorption Spectophotometry (CV-AAS) analysis and descriptive methods from the results of questionnaire interviews. The results show that the mercury levels in mine workers have exceeded the threshold value set by WHO of 4 ppb while the highest mercury level obtained is 44.1 ppb, the lowest mercury level is 8.38 ppb and the control sample is 6.32 ppb, and there are 2 respondents that have symptoms of mercury exposure, namely respondent OP showing symptoms of mercury exposure in the form of frequent tingling, itching, easy fatigue, headache and eye irritation, and respondent YP showing symptoms of mercury exposure in the form of tremors, frequent tingling, itching, weakness of taste buds, difficulty swallowing, diarrhea, and headache. Based on the research results, it is found that the bodies of mining workers in Malomba Village show symptoms of exposure to mercury.

Risk of Trace Element Imbalance in Cases of Occupational Allergic Diseases

Introduction: The relevance of the study is attributed to the lack of knowledge of the mechanisms of development and specifics of the clinical picture of occupational allergic diseases. Objective: To establish the levels of essential trace elements in biological substrates of patients with occupational allergies. Materials and methods: In 2014–2018, we analyzed zinc and copper levels in urine, blood serum, and lymphocytes of patients with occupational allergic skin and respiratory diseases by the atomic absorption method. Relative risk was calculated using a four-field contingency table. Results: In patients with work-related allergic contact dermatitis and bronchial asthma, zinc and copper concentrations in blood serum increased while urinary excretion of these elements decreased. Quantitative patterns of the concentrations of trace elements in body fluids of the patients with skin and respiratory allergies were unidirectional compared to the reference group. Relative risk values showed that lower levels of copper in urine and zinc in blood serum and lymphocytes, as well as higher serum copper indicated the risk of trace element imbalance in the body. Conclusion: The risk of trace element imbalance due to occupational allergic diseases is associated with impaired copper and zinc balance. Our findings prove that the levels of microelements are additional factors that aggravate the course of occupational allergic disorders.

Phase evolution mechanism exploration of vanadium slag during magnesiation roasting by atomic atmosphere method

Magnesiation roasting-acid leaching technique, whose industrial application is hindered by the unknown phase evolution mechanism during magnesiation roasting. Herein, the “atomic atmosphere” method was proposed to explore the phase evolution mechanism at the atomic scale. At the initial roasting stage, FeV2O4 transformed into Fe2O3•V2O3. Then Fe2SiO4 matrix participated in the reaction, resulting in the exposure of V-bearing crystals. The structure of Fe2SiO4 was completely destroyed at 15 min. At 30 min, all V-bearing crystals transformed into vanadate crystals. Then the vanadate crystals continued to grow and the overall vanadium extraction efficiency showed an upward trend. The vanadium atoms changed from the mixture of V4+/V5+ to V5+. At 90 min, V5+, Mg2+, Mn2+, and O2− ions combined to generate Mg2V2O7 and Mn2V2O7. The explored atomic-scale phase evolution mechanism of vanadium slag during magnesiation roasting impels the industrial application of this technique, which can boost green extraction techniques of other resources.

Kinetics of zinc leaching from intermediate feedstocks

The aim of the work was to study the leaching kinetics of zinc from the compound CaO. ZnO, formed during the sintering of dust from electric arc furnaces with limestone, as well as to identify the mechanisms by means which such chemical interactions occur. The object of the study was the dust sinter of electric arc furnaces with limestone obtained at the Chelyabinsk Zinc Plant. It was found that zinc is contained in sinter in the form of readily soluble CaO. ZnO. The elemental composition of the initial dusts and sinter was determined by the spectral atomic emission method using inductively coupled plasma on a Spectroblue optical emission device and spark spectrometry. The phase composition of the materials was studied on a Bruker D8 Advance X-ray diffractometer. The initial sinter was milled to apowder state having a particle size of ~0.04 mm and with a yield of ~97% of the composition, %: 11.9 Zn; 28.5 Ca; 16.6 Fe; 0.38 Mg; 0.14 Pb; 0.05 Cl. Experiments on the leaching of Zn with NaOH solution were carried out at the following parameters: the initial concentration of zinc in the pulp was 0.202 g-ion/dm3 ; alkali concentration – 5‒9 mol/dm3 NaOH; L:S = 9:1; pulp mixing rate – 10‒20 rad. c-1; temperature – 333‒363 K; duration – 0.5–2.5 hours. It has been shown that zinc from sinter passes into solution as sodium tetrahydroxozincate Na2[Zn(OH)4], while calcium remains in the cake, mainly as insoluble Ca(OH)2, which reacts with carbon dioxide to form insoluble calcium carbonate CaCO3. The process of dissolving zinc from the sinter corresponds to the external diffusion mode of mutual transfer of the initial reagents and reaction products through the surface layer of the liquid at the interface of the “liquid–solid” phases with an activation energy value equal to 12.44 kJ/mol. Thus, with the studied parameters of zinc leaching with NaOH solution, the process proceeds in an external diffusion mode. The results are of interest when identifying conditions corresponding to the intradiffusion and kinetic modes of zinc leaching.

Sources, accumulation levels and environmental hazard of heavy metals and metalloids in soils and PM10 fractions of Severobaykalsk

Relevance. The need to study the ecological state of the soil cover of industrial cities, which is the main depositing environment for technogenic emissions of heavy metals and metalloids, to identify the geochemical characteristics of the region and assess the impact on public health. Aim. To assess the sources and accumulation of heavy metals and metalloids in soils and their fraction PM10 in Severobaikalsk and to assess the risks associated with them for public health. Methods. Total content of Zn, As, Cd, Pb, Cr, Co, Ni, Cu, Sb, Mo, V, W, Sr, Bi in soil, coal and ash samples was determined by mass spectral and atomic emission methods with inductive-coupled plasma. Geochemical (KK, Kc, Zc), sanitary and hygienic (Ko) indicators were used. Health risks for adults and children were assessed. Principal component analysis was used. Results. In Severobaikalsk, the priority soil pollutants are Sb, Cu, Pb, Mo, Cr. The soils and their PM10 fraction in the transport zone, where Sb, Cu, Pb, Co, V, W, Ni are accumulated, are the most polluted. The greatest influence on the chemical composition of urban soils and PM10 particles is exerted by emissions from railway infrastructure and coal combustion at the Central Thermal Power Plant (22% for soils in general and 48% for the PM10 fraction). The average total level of contamination of urban soils and PM10 fraction corresponds to a low, non-hazardous level (Zc=6). The total non-carcinogenic risk of soil particles contaminated with heavy metals and metalloids. entering the body of children, exceeded the safe level 1 (from 1.60 in a residential one-story zone to 1.81 in a transport zone). For the adult population, HI values were below the acceptable threshold value. For adult health, there is no carcinogenic risk associated with ingestion or skin contact of As, Cr and Pb. For children, a dangerous risk (ILCRingest 5.56*10–4) of ingestion of carcinogenic heavy metals and metalloids was identified.

Conditions of formation of Vikhoreva river and Ust-Vikhorevsky bay hydrochemical regime (Ust-Ilimsk reservoir)

Relevance. The necessity to control the hydrochemical regime of water bodies significantly affected by anthropogenic impacts. Aim. To study the spatial distribution of major ions and trace element concentrations and identify natural and anthropogenic formation factors of the hydrochemical composition of the Vikhoreva river and Ust-Vikhorevsky bay of the Ust-Ilimsk reservoir. Objects. Waters of the Vikhoreva river before and after inflow of wastewater from the Bratsk industrial zone, waters of the Ust-Vikhorevsky bay (Vikhorevskaya and Burdoyskaya parts) of the Ust-Ilimsk reservoir. Methods. Determination of micronutrients concentrations in water was performed by inductive coupled plasma mass spectrometry, mercury – by atomic absorption method. Cations and anions were determined using standard methods accepted in hydrochemical studies, Sorg – by titrimetric method, oxygen – by iodometric method. Results. In the Vihoreva river water after wastewater inflow from the Bratsk industrial zone, significant transformations of its hydrochemical composition were detected. Along the water area of river decrease of O2 concentrations (up to 0.3 mg O2/l) and increase of Сorg (up to 131 mg/l), SO42– (up to 262 mg/l), K+ (up to 10.6 mg/l), Cl– (up to 220 mg/l), Na+ (up to 240 mg/l), Mn (up to 248.5 mg/l), Cr (up to 7.4 mg/l), to a lesser extent Al (up to 224.1 mg/l), Co (up to 0.26 mg/l), Cu (up to 5.4 mg/l), Zn (up to 43.2 mg/l), Cd (up to 0.126 mg/l), Pb (up to 0.40 mg/l), Hg (up to 0.0032 mg/l) are observed. In surface waters of the Ust-Vikhorevsky bay concentrations of most components of the main ionic composition and trace elements decrease, as compared to the Vikhoreva river water. Maximum concentrations of Mn (511.5 mg/l), Fe (1567.2 mg/l), Co (0.80 mg/l), Pb (0.77 mg/l) were detected in bottom waters. The main ionic composition and trace element concentrations in the Vihoreva river water are determined primarily by anthropogenic factor. At the same time, the hydrochemical regime of the river is effected by natural factors. Inflow of both waters of the highly polluted and forming waters of the channel part of the Ust-Ilimsk reservoir impacts the hydrochemistry of the Ust-Vikhorevsky bay.

Molecular Dynamics Simulation of Bauschinger Effect in Cu Nanowire with Different Crystallographic Orientation

In this study, the Bauschringer Effect (BE) resulting from tension-compression deformation applied to nanowires obtained by placing Cu atoms in , and highly symmetric crystallographic directions was investigated using the Molecular Dynamics (MD) simulation method. The forces between atoms were determined from the gradient of the Embedded Atom Method (EAM) potential function, which includes many-body interactions. It was determined that there is an asymmetry between the stress-strain curves obtained as a result of the tension and compression deformation process applied to the model system. From this asymmetry, it was determined that the yield stress obtained in the drawing process for nanowire with crystallographic orientation was greater than the yield strain obtained as a result of the compression process. In contrast, the opposite was found for nanowires with crystallographic orientation and . In addition, after the yield strain value is exceeded as a result of the drawing process applied to the model nanowire system, compression deformation process was applied at different pre-strain values. The existence of the Bauschinger Effect (BE), which is expressed as the yield strength value as a result of forward loading corresponding to the tension operation, is smaller than the yield value obtained as a result of the compression process in which the loading is removed, was determined. To clarify the effect of BE on Cu nanowires with different crystallographic orientations, Bauschinger Stress parameter (BSP) and Bauschinger Parameter (BP) values were calculated.

Microstructure and Properties of Thin-Film Submicrostructures Obtained by Rapid Thermal Treatment of Nickel Films on Silicon

Nickel films of 40 nm thickness were obtained by means of magnetron sputtering on a single-crystalline silicon substrate. The films were subjected to rapid thermal treatment (RTT) for 7 s until the temperature increased from 200 to 550 °C. By means of the X-ray diffraction method, the structural-phase composition of nickel films before and after RTT was explored. The atomic force microscopy method due to direct contact with the surface under study, made it possible to accurately define the microstructure, roughness, specific surface energy and grain size of the nickel films before and after RTT, as well as to establish the relationship of these parameters with the phase composition and electrical properties of the films. Surface specific resistance was measured using the four-probe method. Based on XRD results, formation of Ni2Si and NiSi phases in the film was ascertained after RTT at 300 °C. At RTT 350–550 °C, only the NiSi phase was formed in the film. The microstructure and grain size significantly depend on the phase composition of the films. A correlation has been established between specific surface energy and resistivity with the average grain size after RTT at 350–550 °C, which is associated with the formation and constant restructuring of the crystal structure of the NiSi phase.

Theoretical investigation on the solid-liquid phase transition of gallium through free energy analysis.

Gallium, renowned for its notably low melting point and unique property of becoming liquid at room temperature, is a valuable constituent in phase change materials. In this study, we investigate the solid-liquid phase transition of gallium using the modified embedded atom method (MEAM) potential. It addresses the technique to compute the free energy difference between the solid and liquid without using a reference state. We examine various thermodynamic and dynamic properties, including density, specific heat capacity, diffusivity, and radial distribution functions. We compute the coexistence temperature of the solid-liquid phase transitions of gallium from free energy analysis. This information is crucial for understanding the behavior of the material under different pressure conditions and can be valuable for various applications, such as materials processing and high-pressure studies. The analysis, findings, and insights of the present work will be of great significance to the broad scientific and engineering communities in the field of phase transformation of materials. A series of molecular dynamics(MD) simulations were conducted using the LAMMPS software packages. The gallium atoms are modeled using the modified embedded atom method (MEAM) potential. To accurately predict the solid-liquid phase transitions of gallium, we calculated free energy by employing the "constrained λ integration" method, coupled with multiple histogram reweighting (MHR). The solid-liquid coexistence line is determined through the Gibbs-Duhem integration technique.