Crystallographic Parameters Research Articles

Investigation on bio-synthesized Ni- and Al-doped cobalt ferrite using lemon juice as eco-fuel

Pure and doped cobalt ferrite (CoFe2O4) nanoparticles were prepared using sol-gel auto-combustion route with the aid of lemon juice as eco-fuel. In this study, Ni2+ and Al3+ ions were chosen as the dopants. The cubic spinel crystal structure of the synthesized ferrite samples was elucidated from the powder X-ray diffraction analysis. The crystallographic parameters associated with the samples were obtained from the Rietveld profile refinement of the diffraction patterns. The precise lattice parameter obtained from the Nelson-Riley extrapolation method is found nearly matches with the lattice parameter obtained from the Rietveld refinement of respective samples. The average crystallite size and microstrain accompanying with the samples were estimated from various methods such as via the Debye-Scherrer method, Williamson-Hall analysis and size-strain plot. By employing Tauc’s plot method, the optical parameters such as the direct bandgap, sub-bandgap and the Urbach energy of all the samples were calculated by analyzing the UV-Visible reflectance spectra. The room temperature magnetic properties of all the samples were estimated from the vibrating sample magnetometry. The nature of magnetic hysteresis revealed the semi-hard ferrimagnetism of the prepared cobalt ferrite samples. Also, the variation of magnetic properties with doping was analyzed. The weakening of interaction among the ions in tetrahedral and octahedral sites causes a decrease in the values of remanent magnetization, saturation magnetization and coercivity of doped samples.

Unraveling the Effect of Stereoisomerism on Mobility-Stretchability Properties of n-Type Semiconducting Polymers with Biobased Epimers as Conjugation Break Spacers.

The development of intrinsically stretchable n-type semiconducting polymers has garnered much interest in recent years. In this study, three biobased dianhydrohexitol epimers of isosorbide (ISB), isomannide (IMN), and isoidide (IID), derived from cellulose, were incorporated into the backbone of a naphthalenediimide (NDI)-based n-type semiconducting polymer as conjugation break spacers (CBSs). Accordingly, three polymers were synthesized through the Migita-Kosugi-Stille coupling polymerization with NDI, bithiophene, and CBSs, and the mobility-stretchability properties of these polymers were investigated and compared with those of their analogues with conventional alkyl-based CBSs. Experimental results showed that the different configurations of these epimers in CBSs sufficiently modulate the melt entropies, surface aggregation, crystallographic parameters, chain entanglements, and mobility-stretchability properties. Comparable ductility and edge-on preferred stacking were observed in polymers with endo- or exo-configurations in IMN- and IID-based polymers. By contrast, ISB with endo-/exo-configurations exhibits an excellent chain-realigning capability, a reduced crack density, and a proceeding bimodal orientation under tensile strain. Therefore, the ISB-based polymer exhibits high orthogonal electron mobility retention of (53 and 56)% at 100% strain. This study is one of the few examples where biobased moieties are incorporated into semiconducting polymers as stress-relaxation units. Additionally, this is the first study to report on the effect of stereoisomerism of epimers on the morphology and mobility-stretchability properties of semiconducting polymers.

A Phase Field Study of the Influence of External Loading on the Dynamics of Martensitic Phase Transformation

An elastoplastic phase field model was employed for simulations to investigate the influence of external loading on the martensitic phase transformation kinetics in steel. The phase field model incorporates external loading and plastic deformation. During the simulation process, the authenticity of the phase field model is ensured by introducing the relevant physical parameters and comparing them with experimental data. During the calculations, loads of various magnitudes and loading conditions were considered. An analysis and discussion were conducted concerning the volume fraction and phase transition temperature during the phase transformation process. The simulation results prominently illustrate the preferential orientation of variants under different loading conditions. This model can be applied to the qualitative phase transition evolution of Fe-Ni alloys, and the crystallographic parameters adhere to the volume expansion effect. It is concluded that uniaxial loading promotes martensitic phase transformation, while triaxial compressive loading inhibits it. From a dynamic perspective, it is demonstrated that external uniaxial loading accelerates the kinetics of martensitic phase transformation, with uniaxial compression being more effective in accelerating the phase transformation process than uniaxial tension. When compared to experimental data, the simulation results provide evidence that under the influence of external loading, the martensitic phase transformation is significantly influenced by the applied load, with the impact of external loading being more significant than that of plastic effects.

A model for calculating the irradiation swelling of AgInCd absorber in nuclear control rods

The actual swelling of AgInCd absorber might exceed the predicted swelling value after years of service in pressurized water reactors, and the chemical and microstructural changes of AgInCd absorber induced by transmutation reactions are the main reason for the swelling acceleration of AgInCd absorber. In the present study, a model for calculating the irradiation swelling of AgInCd absorber in nuclear control rods is developed according to chemical and microstructural changes of AgInCd absorber. In this model, the chemical compositions of AgInCd absorber as a function of the thermal neutron fluence are firstly calculated, and then the volume of AgInCd absorber after irradiation is obtained on the basis of the crystallographic parameters of phases in the AgInCd absorber, and the irradiation swelling of AgInCd absorber is finally calculated. The crystallographic parameters can be obtained by preparing the simulated AgInCd alloys and fitting the experimental data. The model calculating results of irradiation swelling are in good agreement with the actual swelling data in literature. More importantly, the present model can well explain the EPRI results of the acceleration in the diametral swelling rate above 6–8 × 1020 n/cm2 and the decrease in the diametral swelling rate above about 2 × 1021 n/cm2.

Crystal chemical investigations of epidote group minerals from two Bulgarian localities: Effects of Mn content and Mn/Fe ratio on the structural peculiarities

The current study presents results of crystal chemical studies of epidote samples from two Central Rhodope localities. Based on the obtained crystal chemical information, the nomenclature of the investigated species has been justified within the IMA-recommended nomenclature of epidote-group minerals. A comparative study has also been accomplished, including data from the present study as well as literature data from selected epidotes possessing similar crystal structural peculiarities. Certain trends have been derived from the transition metal(s) type and content(s) in the most distorted of the three six-coordinated sites (designated as M3) on selected geometrical and crystallographic parameters. The impact of Mn content and Mn/Fe ratio on the structural peculiarities and coloration of the specimens containing this element are discussed in terms of manifestation of the Jahn-Teller effect on the herein-considered epidote phases.

INFLUENCE OF TEMPERATURE ON THE PROPERTIES OF FREE LOADED INORGANIC OXIDE NANO POWDERS

A comparative study was carried out on the possibility of controlling the average sizes of nano-sized powders of silicon dioxide and aluminum oxide obtained by electron beam evaporation, pyrogenic, liquid chemical and plasma chemical methods, by keeping them in the temperature range of 800 – 1300 ?C in an air atmosphere. The average size of the resulting particles was estimated from specific surface area measurements using the Brunauer–Emmett–Taylor (BET) adsorption method at liquid nitrogen temperature. Crystallographic parameters in the treated powders were assessed using X-ray diffraction analysis. It has been shown that by appropriate choice of temperatures and initial powder, it is possible to achieve an average particle size in the resulting powder close to a given one and a phase composition.

Influence of Synthesis Conditions on the Crystal, Local Atomic, Electronic Structure, and Catalytic Properties of (Pr1−xYbx)2Zr2O7 (0 ≤ x ≤ 1) Powders

The influence of Yb3+ cations substitution for Pr3+ on the structure and catalytic activity of (Pr1−xYbx)2Zr2O7 powders synthesized via coprecipitation followed by calcination is studied using a combination of long- (s-XRD), medium- (Raman, FT-IR, and SEM-EDS) and short-range (XAFS) sensitive methods, as well as adsorption and catalytic techniques. It is established that chemical composition and calcination temperature are the two major factors that govern the phase composition, crystallographic, and local-structure parameters of these polycrystalline materials. The crystallographic and local-structure parameters of (Pr1−xYbx)2Zr2O7 samples prepared at 1400 °C/3 h demonstrate a tight correlation with their catalytic activity towards propane cracking. The progressive replacement of Pr3+ with Yb3+ cations gives rise to an increase in the catalytic activity. A mechanism of the catalytic cracking of propane is proposed, which considers the geometrical match between the metal–oxygen (Pr–O, Yb–O, and Zr–O) bond lengths within the active sites and the size of adsorbed propane molecule to be the decisive factor governing the reaction route.

Potassium complex containing 2,4-dimercaptopyrimidine as ligand: synthesis, x-ray structure and DFT calculations (B3LYP/LanL2DZ)

The reaction of 2,4-dimercaptopyrimidine with potassium borohydride K[BH4] led to the formation of a new polymeric potassium complex. The obtained adduct was characterized by infrared spectroscopy (FT-IR), UV–Vis and single crystal X-ray diffraction, where it was possible to confirm the formation of the product with the following crystallographic parameters: a = 10.4286(16) Å, b = 14.417(2) Å, c = 8.5745(13) Å, α = 90°, β = 108.032(3) ° and γ = 90°. The geometry of the complex, the energy of the Kohn-Sham orbitals (HOMO and LUMO), and the electrostatic potential map (MEP) were calculated using the Density Functional Theory (DFT) at the theoretical level B3LYP/LanL2DZ and the structural parameters are close to those experimentally obtained. Comparison of the formation energies of the title complex and the scorpionate hydrotris{2,4(1H,3H)-pyrimidinedithione}borate, another possible product of the same reaction, indicates that the potassium complex is more favorable by around Hartree.

Numerical Material Testing Method for Hexagonal Close-Packed Metals Based on a Strain-Rate-Independent Finite Element Polycrystal Model

The purpose of this study was to develop a numerical material testing method applicable to hexagonal close-packed (hcp) materials that can predict complex material behavior such as biaxial test results from relatively easy-to-perform uniaxial tests. The proposed numerical material testing method consists of a physical model that represents the macroscopic behavior of the material and a means of determining the included crystallographic parameters using macroscopic experimental data. First, as the physical model, the finite element polycrystal model (FEPM) previously applied by the authors for face-centered cubic (fcc) materials was applied and modified for hcp materials. A unique feature of the FEPM is that it avoids the use of strain-rate-dependent coefficients, whose physical meaning is ambiguous, because the deformation analysis can be performed while automatically determining the activity of all slip systems. The applicability of FEPM to numerical material testing methods was verified in hcp materials through this study. Then, a material parameter optimization process was developed using a genetic algorithm (GA). The proposed method was validated using literature values of magnesium alloy AZ31. First, the proposed optimization process was performed on cast AZ31 using uniaxial tensile and compressive stress—strain curves as teaching data to confirm that the stress—strain curves for the biaxial state could be predicted. Then, the proposed method was applied to rolled sheet AZ31, where the pseudo-anisotropic crystal orientations generated by numerical rolling were used as initial values. The prediction of unknown material data showed that, even in the case of sheets, the crystallographic parameters could be reasonably determined by the proposed optimization process.

X-Ray Diffraction and Raman Spectroscopy Analyses of GaSb-Enriched Si Surface Formed by Applying Diffusion Doping Technique

The paper studies the properties of surface and near-surface region of a single crystalline silicon sample doped with atoms of Ga (AIII) and Sb (BV). n-type single-crystal Si wafers were chosen as substrates, and samples were size of 8×10×0.5 mm3. For diffusion into silicon, Ga and Sb impurities were used with a purity of 99.999 and 99.998, respectively. The authors propose that a new heterostructure might form in the near-surface region of silicon that could be engineered by applying a relatively cheap diffusion method. The experimental and analysis results show that the composition and absorption spectrum of silicon start manifest certain changes, and can be used in the future as a functional material for solar cells. The result showed that randomly located islands with an average diameter of 1–15 µm are formed on the substrate surface. X-ray diffraction analysis was carried out using a Rigaku diffractometer to study the crystallographic parameters of islands formed with the participation of Ga and Sb atoms on the silicon surface. The energy spectrum was studied on Nanofinder High End Raman spectrometer (LOTIS TII) in order to determine the presence of complexes of Ga and Sb atoms within islands formed as a result of diffusion. The optical emission spectra in the new structure were studied using a Lambda 950 spectrophotometer. The measurements were carried out at room temperature, i.e., at 300°K. Having studied the results of X-ray analysis, Raman spectroscopy, and optical spectroscopy, the authors have revealed that Ga and Sb atoms form new Si0.44(GaSb)0.56 and Si0.75(GaSb)0.25-type binary compounds on Si surface.

The Influence of Crystallographic Orientation and Grain Boundary on Nanoindentation Behavior of Inconel 718 Superalloy Based on Crystal Plasticity Theory

The crystal plasticity finite element method (CPFEM) is widely used to explore the microscopic mechanical behavior of materials and understand the deformation mechanism at the grain-level. However, few CPFEM simulation studies have been carried out to analyze the nanoindentation deformation mechanism of polycrystalline materials at the microscale level. In this study, a three-dimensional CPFEM-based nanoindentation simulation is performed on an Inconel 718 polycrystalline material to examine the influence of different crystallographic parameters on nanoindentation behavior. A representative volume element model is developed to calibrate the crystal plastic constitutive parameters by comparing the stress-strain data with the experimental results. The indentation force-displacement curves, stress distributions, and pile-up patterns are obtained by CPFEM simulation. The results show that the crystallographic orientation and grain boundary have little influence on the force-displacement curves of the nanoindentation, but significantly influence the local stress distributions and shape of the pile-up patterns. As the difference in crystallographic orientation between grains increases, changes in the pile-up patterns and stress distributions caused by this effect become more significant. In addition, the simulation results reveal that the existence of grain boundaries affects the continuity of the stress distribution. The obstruction on the continuity of stress distribution increases as the grain boundary angle increases. This research demonstrates that the proposed CPFEM model can well describe the microscopic compressive deformation behaviors of Inconel 718 under nanoindentation.

XRD and SEM analyses of structural properties of LaxBa1−xMnO3 solid solutions

Complex oxides La[Formula: see text]Ba[Formula: see text]MnO3, La[Formula: see text]Ba[Formula: see text]MnO3 and La[Formula: see text]Ba[Formula: see text]MnO3 were synthesized and their structural properties were studied. The structural investigation of the samples is done by incorporating X-ray diffraction (XRD) and scanning electron microscope (SEM) technique at room temperature. The Rietveld method was successfully used for the analysis of the obtained diffraction spectra. It was determined that these compounds have a perovskite structure. Partial substitutions La→Ba do not disturb the ideal perovskite structure and the cubic crystal structure with the space group Pm-3m is preserved. Crystallographic parameters, lattice parameters and interatomic distances were determined for each compound. As a result of SEM studies, it was determined that the size of crystallites in LaxBa[Formula: see text]MnO3 solid solutions ranged from 2 to 10[Formula: see text][Formula: see text]m.

Revealing shear-coupled migration mechanism of a mixed tilt-twist grain boundary at atomic scale

Shear-coupled grain boundary (GB) migration greatly influences the plasticity and creep resistance of nanocrystalline materials. However, the atomistic mechanisms underlying the shear-coupled migration of general mixed tilt-twist GBs (MGBs) remain largely elusive to date. Here, using in-situ high-resolution transmission electron microscopy and molecular dynamics simulations, we uncover the atomic-scale migration behavior of a typical MGB, i.e., 〈001〉{200}/〈01¯1〉{1¯11} GB, during the room-temperature shear deformation of Au nano-bicrystals. Two distinct migration patterns showing the opposite signs of shear-coupling factor were observed and further revealed to be mediated by the motion of GB disconnections with different crystallographic parameters and exhibit different lattice correspondence relations, i.e., 〈001〉{020}-to-〈01¯1〉{200} and 〈001〉{020}-to-〈01¯1〉{111}. Simulation results confirm that the two distinct migration patterns could be activated under different stress/strain states. Moreover, excess GB sliding and GB plane reorientation were found to accommodate the GB migration in both experiments and simulations, likely due to the necessity of establishing a point-to-point lattice correspondence during GB migration. These findings provide atomic-scale experimental evidence on the disconnection-mediated migration of MGBs and elaborate on the hitherto unreported complex shear response of MGBs, which have valuable implications for optimizing the ductility of metallic nanocrystals through controlling GB migration.

Phase equilibria in the Ag8SiSe6-Ag8SiTe6 system and characterization of the solid solutions Ag8SiSe6-xTex

Due to polymorphism and complex crystal structure, compounds of the argyrodite family and phases based on them exhibit several interesting functional properties, such as thermoelectric, photoelectric, optical, as well as ionic conductivity for Cu+ and Ag+ cations. The paper presents the results of the study of phase equilibria in the Ag8SiSe6-Ag8SiTe6 system by DTA, XRD, and SEM methods. Refined data on the melting temperature (1278 K) and polymorphic transitions (315 K and 354 K) of the Ag8SiSe6 compound are presented. The crystallographic parameters of LT-Ag8SiSe6 (Cubic, F-43m, a = 1.0965 nm) and IT-Ag8SiSe6 (Cubic, P4232, a = 1.0891 nm) are also determined. It has been established that the investigated system is quasi-binary and its phase diagram is characterized by the formation of a continuous series of substitutional solid solutions between HT-Ag8SiSe6 and Ag8SiTe6. This process is accompanied by a strong decrease in the temperatures of polymorphic transformations of Ag8SiSe6, which leads to the stabilization of the ion-conducting cubic phase at room temperature in the >10 mol% Ag8SiTe6 compositions area. The crystal lattice parameters of the synthesized solid solutions are calculated by indexing the powder diffraction patterns. The stabilization of the high-temperature cubic phase at room temperature achieved by us presents new opportunities for the development of environmentally friendly thermoelectrics and ion-electronic conductors based on silicon argyrodites with desired composition and properties.

Enhanced Diclofenac Photomineralization under Solar Light Using Ce1−xZnxO2−x Solid Solution Catalysts: Synergistic Effect of Photoexcited Electrons and Oxygen Vacancies

The present work describes the synthesis, characterization, and photomineralization activity of synthesized Ce1−xZnxO2−x solid solution catalysts allowing the degradation of diclofenac as a model of anti-inflammatory medicines in water. The oxygen-deficient photocatalyst Ce1−xZnxO2−x (CeZnx), produced by mixing ZnO and CeO2, is characterized for its crystallographic parameters, specific surface area, and morphology. Photomineralization activity determination using TOC analysis shows efficient diclofenac photo-oxidation under sunlight. Moreover, the results indicate that the coexistence of Zn2+ and Ce4+ and the oxygen vacancies rate in CeZnx solid solution are key factors for strong drug mineralization. Ultimately, CeZn0.1, which is one of the photocatalysts synthesized in the present work, represents a cheap and efficient reagent for organic matter photomineralization in wastewater.

Combustion synthesis of ultra-high-temperature solid solutions (ZrxNb1-x)B2. Part 2: Fine-tuning the mechanical properties and thermal conductivity of Zr–Nb–B diboride solid solutions for ultra-high temperature applications

In Part 1 of this study, we investigated the macrokinetic parameters and phase formation mechanism in the combustion front of Zr–Nb–B mixtures. In the second part, we produced consolidated samples of solid solutions NbB2-(0.100%)ZrB2 by hot pressing the combustion-derived powders at 1900 °C. By measuring the crystallographic parameters, mechanical and thermophysical properties of the produced bulk samples, we obtained valuable insights into the behavior of the solid solutions. Our results pave the way for the application-specific fine-tuning of the mechanical properties and thermal conductivity of diboride solid solutions in the Zr–Nb–B system for ultra-high temperature applications. Our findings have significant implications for the development of advanced materials with outstanding performance in extreme environments.

Crystallographic parameters of Bi2O3 and reduced Graphene-Bi2O3 nano-composite thin film

The Bi2O3 and reduced graphene (RG)-Bi2O3 nano-composite thin films are synthesized using modified sol-gel process. For structural examination, the samples are analyzed using XRD. Using the Scherrer equation and a modified Scherrer plot, the sample's structural parameters are calculated. The materials' size and strain were estimated from different methods like modified Williamson-Hall (W–H), Halder-Wagner (H–W), and Size Strain Plot (SSP) with logical validity. The different crystallographic parameters obtained are compared and presented in this work.

Synthesis, crystal structure, and Hirschfeld surface analysis of novel ethyl 5-bromo-2-(4-methoxyphenyl) oxazole-4-carboxylate

A new oxazole derivative, ethyl 5-bromo-2-(4-methoxyphenyl) oxazole-4-carboxylate, was synthesized and characterized by IR spectroscopy, 13C NMR, Mass spectroscopy, and single-crystal X-ray diffraction analysis. The asymmetric unit of the title compound has two independent molecules (A and B) arranged in an inverted planar orientation, stabilized by intramolecular C-H…O and C-H…N hydrogen bonds and intermolecular C-H…O hydrogen bonds. The crystallographic parameter for the structure C13H12BrNO4 is M =326.15 g/mol, monoclinic, sp. gr. P21/n (no. 14), a = 14.828(2) Å, b = 7.1335(9) Å, c = 25.119(2) Å, β = 100.066(11) °, V = 2616.1(6) Å3, Z = 8. Hirschfeld surface analysis and two-dimensional fingerprint plots provided insight into the short intermolecular interactions, and it was found that H···H (34.4%) interactions contributed the most to the intermolecular interactions. In contrast, the contribution of C · · · C (2.5 %) remained the least among all the interactions.

Oxidation kinetics and non-Marcusian charge transfer in dimensionally confined semiconductors

Electrochemical reactions represent essential processes in fundamental chemistry that foster a wide range of applications. Although most electrochemical reactions in bulk substances can be well described by the classical Marcus-Gerischer charge transfer theory, the realistic reaction character and mechanism in dimensionally confined systems remain unknown. Here, we report the multiparametric survey on the kinetics of lateral photooxidation in structurally identical WS2 and MoS2 monolayers, where electrochemical oxidation occurs at the atomically thin monolayer edges. The oxidation rate is correlated quantitatively with various crystallographic and environmental parameters, including the density of reactive sites, humidity, temperature, and illumination fluence. In particular, we observe distinctive reaction barriers of 1.4 and 0.9 eV for the two structurally identical semiconductors and uncover an unusual non-Marcusian charge transfer mechanism in these dimensionally confined monolayers due to the limit in reactant supplies. A scenario of band bending is proposed to explain the discrepancy in reaction barriers. These results add important knowledge into the fundamental electrochemical reaction theory in low-dimensional systems.

Dielectric and Magneto-dielectric properties of GdFeO3 modified PbTiO3 nanofibrous mats obtained through electrospinning technique

This study intends to create and analyze electrospun nanofibrous mats of GdFeO3 doped PbTiO3 i.e Pb0.8Gd0.2Ti0.8Fe0.2O3 (GF-PT) using sol gel method. The polyvinylpyrrolidone PVP/GF-PT material was attempted to generate a highly viscous sol that is used to transform into nanofibers utilizing various parameters. The crystallographic parameters were estimated using X-ray diffraction (XRD) patterns, which supported single phase tetragonal structure. Also, Scherer equation was used to calculate the typical nanocrystallite size of the manufactured nanofibrous mats, and the result was 15.92 nm. The morphological investigations showed that a variety of factors, such as applied voltage, flow rate, and needle-collector distance, had a significant impact on the average diameter of nanofibrous mats. The nanofibers displayed ferromagnetic behavior and exhibited residual magnetism of approximately 0.0257 emu/g. The created nanofibers exhibit significant magneto-electric (ME) coupling characteristics having the highest magneto-dielectric response (MDR) at 1.2 T of about −38.62 % and the calculated magneto- dielectric coefficient value is −275.05 emu2/g2.