Influence of heating rate, temperature, pressure on the structure, and phase transition of amorphous Ni material: A molecular dynamics study

Tuning structural properties, morphology and magnetic characteristics of nanostructured Ni-Co-Fe/ITO ternary alloys by galvanostatic pretreatment process

In this research, the structural properties, surface morphology, and magnetic characteristics of nanostructured ternary ferromagnetic alloys grown by a cost-effective and effortless two-step electrochemical deposition method on indium tin oxide (ITO) substrates with and without a galvanostatic pretreatment process (GPP) were examined. The GPP was applied at various pretreatment current densities (PCDs) such as -10, -20, and - 30 mA/cm2 . The effect of the PCD on the Ni, Co, and Fe contents is found to be insignificant and all resultant Ni-Co-Fe thin films show an abnormal co-deposition. The films have nano-sized crystallites ranging from 17.3 to 19.6 nm and showed a face-centered cubic structure with the [111] preferential growth. Compared to the non-GPP applied Ni-Co-Fe film, growing the ternary Ni-Co-Fe film on ITO at the PCD of -30 mA/cm2 causes an improvement in the crystal quality and a reduction in the particle size from 150 ± 50 to 70 ± 20 nm. A decrement in the surface roughness and coercivity was also achieved by applying the GPP at the PCD of -30 mA/cm2 , but the opposite is true for the GPP performed at the PCD of -10 mA/cm2 . The GPP has an effect on the magnetic Squareness Ratio (SQR), but the influence of the PCD on the SQR parameter is negligible. The obtained findings reveal that the properties of the Ni-Co-Fe/ITO ternary alloys can be tuned through the GPP applied in various PCDs. HIGHLIGHTS: • The effect of the PCD on the Ni, Co, and Fe contents is found to be insignificant. • The films have nano-sized crystallites and showed a face-centered cubic structure with the [111] preferential growth. • The analysis reveals that the GPP changes the crystal quality, Hc parameter, surface roughness, and particle size of the films. • The GPP has an effect on the magnetic squareness ratio (SQR), but the influence of the PCD on the SQR parameter is negligible. • The films had nano-sized crystallites ranging from 17.3 to 19.6 nm. • The films were ferromagnetic, and the Hc and SQR parameters of the films ranged from 30.2 to 42.7 Oe and from 8.8% to 19.6%.

A Study on the Structural Features of Amorphous Nanoparticles of Ni by Molecular Dynamics Simulation

This study deals with the impact of the heating rate (HR), temperature (T), and the number of atoms (N) on the structural features of amorphous nanoparticles (ANPs) of Ni by molecular dynamics simulation (MDS) with the Pak–Doyama pair interaction potential field (PD). The obtained results showed that the structural features of ANPs of Ni are significantly affected by the studied factors. The correlation between the size (D) and the N was determined to be D~N−1/3. The energy (E) was proportional to N−1, and the Ni-Ni link length was 2.55 Å. The glass transition temperature (Tg) derived from the E-T graph was estimated to be 630 K. An increase in the HR induced a change in the shape of the ANPs of Ni. Furthermore, raising the HR caused an enhancement in the D and a decrement in the density of atoms. The obtained results are expected to contribute to future empirical studies.

Determination of Young Modulus and Stress-Strain Curve for Metal Fe and Interstitial Alloy FeC

In this research, the numerical calculation for elastic and nonlinear strains of Fe metal and FeC alloy under different pressures has been performed by the statistical moment method SMM with Mie–-Lennard–Jones potential (MLJ) and Embedded-Jones potential Atom Method (EAM). The analysis reveals that an enhancement in the concentration (cC) from 0 to 5% causes a decrement in the Young’s modulus (E) at room temperature (T = 300 K) for FeC. These calculated results are consistent with the experimental results. In addition, the obtained stress-strain curves for Fe are in perfect agreement with the experimental curves. Besides, increasing the cC for a continuous strain decreases the stress, showing that adding C to Fe to form FeC steel will increase strength and hardness, but decrease elasticity and hardness. The results obtained will be very useful not only for experimental studies but also for theoretical studies of metals and their interstitial alloys.

Effects of Number of Atoms and Doping Concentration on the Structure, Phase Transition, and Crystallization Process of Fe1-x-yNixCoy Alloy: A Molecular Dynamic Study

In this study, molecular dynamics simulations are employed to study the influencing factors such as doping concentration, number of atoms, and temperature on the structural characteristics, phase transition, and crystallization of Fe1-x-yNixCoy alloy. The results show that Fe1-x-yNixCoy alloy always exists with three metals, Fe, Ni, and Cu, which are distributed quite evenly according to the ratio of tap phase concentration. In Fe1-x-yNixCoy alloy, there are always six types of links, Fe–Fe, Fe–Ni, Fe–Co, Ni–Ni, Ni–Co, and Co–Co. Calculated results showed with the increases in the doping concentration, the length of links (r) has a constant value and the height g(r) of the Radial Distribution Function (RDF) has a modified value. The process of increasing the concentration of Fe doping, and reducing the concentration of Co doping leads to an increase in crystallization, a decrease in the size (l) of the alloy, and the total energy of the system (Etot) increases and then decreases. Similarly, increasing the number of atoms leads to an increase in crystallization, but with an increase in temperature, the crystallization process decreases (that corresponds to the change in the number of structural units for the Face-centered cubic (FCC), Hexagonal Close-Packed (HCP), Body-centered cubic (BCC), and Amorphous (Amor)). The obtained results serve as a basis for experimental research in developing new magnetic materials in the future.

Rapidly predicting Kohn-Sham total energy using data-centric AI

Predicting material properties by solving the Kohn-Sham (KS) equation, which is the basis of modern computational approaches to electronic structures, has provided significant improvements in materials sciences. Despite its contributions, both DFT and DFTB calculations are limited by the number of electrons and atoms that translate into increasingly longer run-times. In this work we introduce a novel, data-centric machine learning framework that is used to rapidly and accurately predicate the KS total energy of anatase [Formula: see text] nanoparticles (NPs) at different temperatures using only a small amount of theoretical data. The proposed framework that we call co-modeling eliminates the need for experimental data and is general enough to be used over any NPs to determine electronic structure and, consequently, more efficiently study physical and chemical properties. We include a web service to demonstrate the effectiveness of our approach.

Synthesis and Characterization of Polypyrrole Film Doped with Both Molybdate and Salicylate and Its Application in the Corrosion Protection for Low Carbon Steel

Polypyrrole (PPy) films doped with molybdate and salicylate have been successfully electropolymerized on low carbon steel in aqueous solutions containing both molybdate and salicylate in a one-step process that did not require any pre-treatment of the steel substrate. Salicylate-doped PPy films were synthesized in the same way for comparison. The steel surface was rapidly inhibited and the PPy-based films were formed on it easily. The PPy-based films were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray, and thermal gravimetric analysis methods. The corrosion protection performance of the coatings was investigated with electrochemical impedance spectroscopy, open circuit potential (OCP), salt spray test, and Tafel polarization. It was found that in the presence of both molybdate and salicylate as dopants, the films on steel could present a better corrosion resistance than PPy film doped with only salicylate. The self-healing property of PPy-based films was observed on the OCP measurement with the fluctuation of rest potential. The salt spray test results showed that the PPy film doped with both salicylate and molybdate was more salt-resistant than the PPy film doped with only salicylate. The results suggest that the PPy coatings doped with both molybdate and salicylate are potential for application as metallic anti-corrosion coatings.

New insights on the factors affecting the heterogeneous kinetics of bulk Fe2O3 on the Earth: A molecular dynamic simulation

This study aims to provide new insights into the influencing factors of the Earth (low temperature, depth, and annealing time) on the heterogeneous kinetics of bulk Fe2O3 by the molecular dynamics simulation method. The obtained results show that there is an influence of the low temperature corresponding to the temperature of liquefied gases, such as helium (4.212 K), nitrogen (77 K), argon (83.8058 K), oxygen (90 K), and carbon (194.5 K), the depth (h) of the Earth’s surface from h0 = 0 km to h5* = 6370 km that corresponds to the temperature (T) from T = 300 K to T = 7000 K and the pressure (P) from P = 0 GPa to P = 360 GPa, and then annealing time (t) (120 ps) on the heterogeneous kinetics of bulk Fe2O3, such as the Radial Distribution Function (RDF), Coordination Number (CN), angular distribution, number of structural units, size (l), and energy (E). When the temperature increases in the low temperature (T) region at zero pressure (P), the link length (r), RDF height, size, CN, and the number of structural units FeO4, FeO5, and FeO6 do not change significantly, but only the very large change in E serves as the basis for future research on the mechanical properties and electrical conductivity of semiconductor materials. When the depth (h) of the Earth’s surface and the thermal annealing time at different locations are increased, the characteristic quantities of dynamic dynamics change greatly, including the disappearance of FeO4 at depth h1 ≥ 17.5 km and the appearance of additional structural units FeO7, FeO8, and FeO9 at h3 ≥ 1742 km and FeO10 at h5 ≥ 5562.5 km.

The Influence of the Substrate and External Magnetic Field Orientation on FeNi Film Growth

The magnetic field-assisted electrodeposition of iron–nickel thin films on different substrates (aluminum, silver, and brass) was investigated. The process was performed galvanostatically in a sulfate solution. The same chemical and electrical conditions were applied for each sample growth, but the time restrictions and the external magnetic field orientation were changeable. The obtained results show a variation of surface morphology and composition dependence on the selected surfaces as a consequence of the presence and orientation of the external magnetic field. We discussed that the FeNi crystal structure depends on the film thickness. The results show the reduction of the film thickness after the external magnetic field application—a decrease of deposition rate.The FeNi alloy’s morphology, composition, and magnetic properties were investigated by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), and Mössbauer spectroscopy (MS).

Electrochemical Deposition of Fe–Co–Ni Samples with Different Co Contents and Characterization of Their Microstructural and Magnetic Properties

In this study, to explore the effect of Co contents on the electroplated Fe–Co–Ni samples, three different Fe–Co33–Ni62, Fe–Co43–Ni53, and Fe–Co61–Ni36 samples were electrochemically grown from Plating Solutions (PSs) containing different amounts of Co ions on indium tin oxide substrates. Compositional analysis showed that an increase in the Co ion concentration in the PS gives rise to an increment in the weight fraction of Co in the sample. In all samples, the co–deposition characteristic was described as anomalous. The samples exhibited a predominant reflection from the (111) plane of the face–centered cubic structure. However, the Fe–Co61–Ni36 sample also had a weak reflection from the (100) plane of the hexagonal close–packed structure of Co. An enhancement in the Co contents caused a strong decrement in the crystallinity, resulting in a decrease in the size of the crystallites. The Fe–Co33–Ni62 sample exhibited a more compact surface structure comprising only cauliflower–like agglomerates, while the Fe–Co43–Ni53 and Fe–Co61–Ni36 samples had a surface structure consisting of both pyramidal particles and cauliflower–like agglomerates. The results also revealed that different Co contents play an important role in the surface roughness parameters. From the magnetic analysis of the samples, it was understood that the Fe–Co61–Ni36 sample has a higher coercive field and magnetic squareness ratio than the Fe–Co43–Ni53 and Fe–Co33–Ni62 samples. The differences observed in the magnetic characteristics of the samples were attributed to the changes revealed in their phase structure and surface roughness parameters. The obtained results are the basis for the fabrication of future magnetic devices.

The Study of the Influence of Matrix, Size, Rotation Angle, and Magnetic Field on the Isothermal Entropy, and the Néel Phase Transition Temperature of Fe2O3 Nanocomposite Thin Films by the Monte-Carlo Simulation Method

In this paper, the study of the influence of the matrix structure (mxm) of thin-film, rotation angle (α), magnetic field (B), and size (D) of Fe2O3 nanoparticle on the magnetic characteristic quantities such as the magnetization oriented z-direction (MzE), z-axis magnetization (Mz), total magnetization (Mtot), and total entropy (Stot) of Fe2O3 nanocomposites by Monte-Carlo (MC) simulation method are studied. The applied MC Metropolis code achieves stability very quickly, so that after 30 Monte Carlo steps (MCs), the change of obtained results is negligible, but for certainty, 84 MCs have been performed. The obtained results show that when the mxm and α increase, the magnetic phase transition appears with a very small increase in temperature Néel (TNtot). When B and D increase, TNtot increases very strongly. The results also show that in Fe2O3 thin films, TNtot is always smaller than with Fe2O3 nano and Fe2O3 bulk. When the nanoparticle size is increased to nearly 12 nm, then TNtot = T = 300 K, and between TNtot and D, there is a linear relationship: TNtot = −440.6 + 83D. This is a very useful result that can be applied in magnetic devices and in biomedical applications.

DFT study on some polythiophenes containing benzo[d]thiazole and benzo[d]oxazole: structure and band gap

The content of this paper focuses/shed light on the effects of X (X = S in P1 and X = O in P2) in C11H7NSX and R (R = H in P3, R = OCH3 in P4, and R = Cl in P5) in C18H9ON2S2-R on structural features and band gaps of the polythiophenes containing benzo[d]thiazole and benzo[d]oxazole by the Density Function Theory (DFT) method/calculation. The structural features including the electronic structure lattice constant (a), shape, total energy (Etot) per cell, and link length (r), are measured via band gap (Eg) prediction with the package of country density (PDOS) and total country density (DOS) of material studio software. The results obtained showed that the link angle and the link length between atoms were not changed significantly while the Etot was decreased from Etot = - 1904 eV (in P1) to Etot = - 2548 eV (in P2) when replacing O with S; and the Etot of P3 was decreased from Etot = - 3348 eV (in P3) when replacing OCH3, Cl on H of P3 corresponding to Etot = - 3575 eV (P4), - 4264 eV (P5). Similarly, when replacing O in P1 with - S to form P2, the Eg of P1 was dropped from Eg = 0.621 eV to Eg = 0.239 eV for P2. The Eg of P3, P4, and P5 is Eg = 0.006 eV, 0.064 eV, and 0.0645 eV, respectively. When a benzo[d]thiazole was added in P1 (changing into P3), the Eg was extremely strongly decreased, nearly 100 times (from Eg = 0.621 eV to Eg = 0.006 eV). The obtained results serve as a basis for future experimental work and used to fabricate smart electronic device.