Crystal structure and magnetic property correlations in Ba1−x Sr x Fe12O19 (0 ≤ x ≤ 1) hexaferrites

First principle calculation of structural, electronic, optical, elastic and thermodynamic properties of group IIA metal iodides: Structure-property correlation

Room-temperature ferromagnetism on ZnO nanoparticles doped with Cr: An experimental and theoretical analysis

Deciphering Benzene–Heterocycle Stacking Interaction Impact on the Electronic Structures and Photophysical Properties of Tetraphenylethene-Cored Foldamers

In this work we report on the correlation between the structural properties, i.e., crystalline/amorphous phase ratio and grain size, and the electrical transport properties of hydrogenated silicon thin films. The samples were deposited by means of pulsed laser ablation of a high purity silicon target in presence of hydrogen gas. Infrared spectroscopy measurements showed a monohydride preferential incorporation at the lower hydrogen pressures. The Raman spectroscopy studies of the TO phonon line suggest that crystallinity and hydrogenation of the films, deposited at room temperature, can be properly adjusted as a function of the deposition parameters. The temperature dependence of both the dark and the photo electrical conductivity shows a thermally activated behavior, which is strictly related to the silicon microstructure and to the hydrogen content and bonding configuration.

Structural and magnetic properties of Fe-rich FexMn1−x ultrathin alloy films on Cu(1 1 1 7)

ABSTRACTA controlled esterification of starch to replace the OH moieties with bio‐derived medium chain fatty acids, and the changes in the polymer structure and properties for material applications is investigated in this research. The esterification is conducted via a homogeneous esterification process using an activated lauric acid (C12) in the presence of a base catalyst. The degree of esterification through the replacement of hydroxyl groups of starch was estimated using elemental analysis (EA) and proton NMR. The effect of the modification on the structural and material properties of the modified starch polymer is elucidated by evaluating the changes in morphology, network thermal stability, hydrophobicity, solubility profile, and thermal transition events. Scanning electron microscopy imaging reveals structural changes ranging from surface roughness to complete disruption depending on the degree of substitution. This is confirmed by XRD. Because of the esterification of starch, the resulting polymers become melt processable thermoplastic that forms a transparent film with an elastic storage modulus of up to 226 MPa at room temperature. This shows that the starch–fatty acid polymer can be used for various industrial and advanced material applications without any other plasticizers or modifiers. The final material is completely bio‐based, and is expected to be biodegradable in the environment. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2611–2622

Fluorinated electrode materials for high-energy batteries

An increase in the amount of nickel in LiMO2 (M = Ni, Co, Mn) layered system is actively pursued in lithium‐ion batteries to achieve higher capacity. Nevertheless, fundamental effects of Ni element in the three‐component layered system are not systematically studied. Therefore, to unravel the role of Ni as a major contributor to the structural and electrochemical properties of Ni‐rich materials, Co‐fixed LiNi0.5+xCo0.2Mn0.3–xO2 (x = 0, 0.1, and 0.2) layered materials are investigated. The results, on the basis of synchrotron‐based characterization techniques, present a decreasing trend of Ni2+ content in Li layer with increasing total Ni contents. Moreover, it is discovered that the chex.‐lattice parameter of layered system is not in close connection with the interslab thickness related to actual Li ion pathway. The interslab thickness increases with increasing Ni concentration even though the chex.‐lattice parameter decreases. Furthermore, the lithium ion pathway is preserved in spite of the fact that the c‐axis is collapsed at highly deintercalated states. Also, a higher Ni content material shows better structural properties such as larger interslab thickness, lower cation disorder, and smoother phase transition, resulting in better electrochemical properties including higher Li diffusivity and lower overpotential when comparing materials with lower Ni content.

The effect of strontium substitution on structural, magnetic, and dielectric properties of a multiferroic Y-type hexaferrite (chemical formula Ba2−xSrxMg2Fe12O22 with 0 ≤ x ≤ 2) was investigated. Y-type hexaferrite phase formation was not affected by strontium substitution for barium, in the range 0 ≤ x ≤ 1.5, confirmed by x-ray diffraction and Raman spectroscopy measured at room temperature. Two intermediate magnetic spin phase transitions (at tempertures TI and TII) and a ferrimagnetic-paramagnetic transition (at Curie temperature TC) were identified from the temperature dependence of the magnetic susceptibility. Magnetic transition temperatures (TI, TII, and TC) increased with increasing strontium content. Magnetic hysteresis measurements indicated that by increasing strontium concentration, the coercivity increases, while the saturation magnetization decreases. The 57Fe NMR spectrum of the Y-type hexaferrite measured at 5 K and in zero magnetic field showed remarkable differences compared to that of other hexaferrites due to their different number of tetrahedral and octahedral iron sites. The temperature and frequency dependence of the dielectric permittivity evidenced broad peaks with frequency dispersion in correspondence of the Curie temperature.

Reverse micellar synthesis, structural characterization and dielectric properties of Sr-doped BaZrO3 nanoparticles

Lead–free Sr[Formula: see text]CaxTiO3 ([Formula: see text]) ceramics were synthesized via a solid state reaction technique at room temperature. The effects of ionic substitutions in A-sites between strontium and calcium on the structural and dielectric properties were investigated. XRD technique was used to identify the crystal structure and to demonstrate the phase purity. SEM observations have shown homogeneous morphologies for all samples. Dielectric measurements were investigated for a wide range of frequency (100[Formula: see text]Hz–1[Formula: see text]GHz) and temperature (25[Formula: see text]C–250[Formula: see text]C). Strontium substitution by calcium has not only led to a decrease in the dielectric permittivity value, but also to the loss tangent value by a considerable factor. Interesting values of the quality factor and the quite constant value [Formula: see text] in extended frequency and temperature ranges show that SCT ceramic could be a real candidate for the development of monolithic ceramic capacitors dedicated to high-frequency lead-free components and/or to extremely high-temperature environments.

For efficient production of lithium ion batteries, the growing demands on the production process, particularly a reduction of processing costs which consist of process time, material and energy consumption, must be met. In this regard, the mixing process is of particular importance. Its quality significantly determines the properties of the produced electrode paste and consequently the quality of the subsequent process steps (coating, drying) and finally of the electrochemical performance, including longevity and fast-charging capability, of the fabricated electrodes and batteries [1,2]. Process parameters and equipment setup for the mixing process need to be optimized such that the electrode compounds including active material(s), binder(s) and conductive additive(s) are efficiently deagglomerated, homogenized and dispersed while the generation of particle agglomerates due to insufficient deagglomeration and particle fractures due to excessive energy input is prevented. The state-of-the-art process for electrode paste production is a batch-type process which offers high flexibility particularly beneficial in the field of academic research where novel materials are commonly only available in limited scales. With respect to upscaling and production on industrial scales, though, innovative continuous mixing processes represent a promising alternative since they allow for continuous production of electrode pastes with consistently high quality [3].Therefore, in this study an innovative continuous mixing process using a twin-screw extruder is investigated for graphite-based aqueous anode formulations for high-power applications.For systematic adaption of relevant properties of the electrode paste (e.g., viscosity and particle size distribution) in the extrusion process the kneading concentration is one of the key machine parameters. Varying the kneading concentration for different active materials, a clear correlation to the change in viscosity can be observed up to a certain reversal point where the opposite behavior and a change of the rheological behavior is identified. The underlying mechanism for the observed behavior and its impact on the material and battery cell level is revealed by elaborating further analysis (particle size analysis, scanning electron microscopy, X-ray diffraction, electrochemical cycling). Beyond that, it is also presented how process and product properties correlate and how monitoring the machine parameters can indicate the observed change of the characteristics of the electrode paste.Literature[1] Haarmann, Matthias, Wolfgang Haselrieder, and Arno Kwade. "Extrusion‐Based Processing of Cathodes: Influence of Solid Content on Suspension and Electrode Properties." Energy Technology 8.2 (2020): 1801169.[2] Bockholt, Henrike, et al. "The interaction of consecutive process steps in the manufacturing of lithium-ion battery electrodes with regard to structural and electrochemical properties." Journal of Power Sources 325 (2016): 140-151.[3] Haarmann, Matthias, Desiree Grießl, and Arno Kwade. "Continuous Processing of Cathode Slurry by Extrusion for Lithium‐Ion Batteries." Energy Technology (2021): 2100250.

Organic photovoltaics (OPVs) have held on to the race for providing a sustainable source of energy for more than two decades, and ternary OPVs have emerged as a promising candidate for harnessing solar energy. While the ternary OPVs have potential, optimization of the process parameters, particularly for deriving active-layer morphologies with high efficiencies, is non-trivial as the parameter space is large and a theoretical framework is necessary. This is specifically important for determining the appropriate compositions of the ternary blend which, upon phase-separation, lead to the formation of the heterogenous active layer with a distribution of three phases. In this paper, we present an approach for deriving both the process–structure and structure–property correlations based on the diffuse-interface approach. Herein, we derive process–structure correlations using phase-field simulations based on the Cahn–Hilliard formalism for modeling phase-separation in ternary systems where a third component that acts as an acceptor is added to a binary OPV. This leads to structures that can be classified as donor–acceptor–acceptor. Thereafter, we derive the structure–property correlations again using a diffuse interface approach for deriving the electronic properties such as the efficiency, fill-factor, short-circuit current, and the open-circuit voltages for the simulated microstructures involving the three phases in the active layer. Thus, using a combination of the process–structure and structure–property correlations, optimal compositions can be determined. Further, in order to expedite the theoretical prediction, a robust and elegant data analytics model is built using dimensionality reduction techniques.

The effect of annealing temperature on the structural and magnetic properties of a rare earth (La3+) doped cobalt ferrite with fine sediment from the Bengawan Solo River as the source of Fe3+ has been studied. Co-presipitation method is use for preparation nanoparticles whole this experiment. In order to modified the physical properties, the annealing treatment of 2000C, 3000C, and 4000C are performed. The obtained nanoparticles are characterized their structural properties by using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. Then, magnetic properties evaluated by using Vibrating Sample Magnetometer (VSM). XRD results have shown that there is an increase in crystallite size with an increase in the given annealing temperature from 24.56 nm to 27.83 nm. The increase in crystallite size can be attributed to the increase in the internal energy of the crystal structure which promotes atomic diffusion. Meanwhile, there is a decrease in the value of the lattice parameter with an increase in the given annealing temperature. The decrease in lattice parameters with increasing crystallite size is generally due to the lattice parameters reaching a minimum energy with increasing crystallite size. The formation of La3+-O2- for the incorporation of rare earth ions into the lattice requires high energy. The FTIR results show an absorption that appears at the peak around ~580 cm-1. This indicates that the La3+ cation has successfully replaced the original structure of cobalt ferrite. The VSM results show that there is an increase in the value of Hc with an increase in the annealing temperature given from 100 Oe to 160 Oe. This is supported by the increase of anisotropy constant and increasing temperature annealing.

For a detailed understanding of complex semiconductor heterostructures and the physics of devices based on them, a systematic determination and correlation of the structural, chemical, electronic, and optical properties on a micro- or nano-scale is essential. Luminescence techniques belong to the most sensitive, non-destructive methods of semiconductor research. The combination of luminescence spectroscopy with the high spatial resolution of a scanning electron microscope, as realized by the technique of cathodoluminescence microscopy, provides a powerful tool for the optical nano-characterization of semiconductors, their heterostructures as well as their interfaces. Additional access to the local electronic and structural properties is provided by micro-Raman spectroscopy, e.g. giving insight into the local free carrier concentration and local stress. In this paper, the properties of group-III-nitrides are investigated by highly spatially and spectrally resolved cathodoluminescence microscopy in conjunction with micro-Raman spectroscopy. Complex phenomena of self-organization and their strong impact on the microscopic and nanoscopic properties of both binary and ternary nitrides are presented. As the ultimate measure of device performance, the microscopic properties of light emitting diodes are assessed under operation. Using micro-electroluminescence mapping in the optical microscope as well as in the near field detection mode of a scanning near field optical microscope, the microscopic origin of the macroscopic spectral red shift in light emitting diodes is identified. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)