Increase In Structural Disorder Research Articles

Assessing the electromagnetic shielding effectiveness of coconut coir composites with varying iron particle concentrations

This study investigates the electromagnetic shielding effectiveness of Coconut Coir-based Porous Carbon (CCPC) composites with varying iron (Fe) particle concentrations, specifically focusing on four different weight ratios of CCPC/Fe-80, CCPC/Fe-60, CCPC/Fe-40, and CCPC/Fe-20. The novelty of this work lies in the use of sustainable coconut coir as a base material, emphasizing its eco-friendly and cost-effective attributes for Electromagnetic interference (EMI) shielding applications. The significance of varying iron particle concentrations is highlighted to optimize electromagnetic shielding effectiveness. Comprehensive analyses were conducted on these composites. X-Ray Diffraction (XRD) analysis confirmed the presence of crystalline Fe particles and amorphous carbon, with crystalline sizes determined via Williamson-Hall (W-H) plot, Scherrer Equation, and Strain Size Plot (SSP) ranging from 17.33 nm to 18.01 nm for the former. Raman spectroscopy revealed distinctive D and G bands, with intensity ratios indicating a slight increase in structural disorder with higher Fe content. UV-Visualization spectroscopy demonstrated distinct absorption peaks, with higher Fe content resulting in more pronounced absorbance and lower band gap energies. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses provided detailed insights into the material's microstructure and elemental composition, confirming the successful integration of Fe particles within the porous carbon matrix. Vector Network Analyzer (VNA) testing measured the reflection loss (RL), showing values in the range of −26.4 dB to −20.2 dB, for 2 mm thick samples, corresponding to electromagnetic wave attenuation of over 99%. These results underscore the potential of CCPC/Fe composites, particularly in applications requiring effective Electromagnetic (EM) wave attenuation. This research offers a sustainable and cost-effective solution, contributing significantly to the field of materials science by enhancing electromagnetic compatibility in various technological applications.

Raman spectroscopy study of disorder in cation sublattice of nonstoichiometric and annealed ZnSnN2

This study examines the specific characteristics of Raman scattering observed in ZnSnN2 samples produced via magnetron co-sputtering. The spectra demonstrate a high degree of similarity to the phonon density of states. This phenomenon is caused by the presence of SnZn substitutional defects, which disrupt the ideal crystal structure and generate so-called defect-induced Raman modes across the entire first Brillouin zone. An increase in the elemental content of Sn leads to a decrease in the intensity of the 230 cm⁻1 and 660 cm⁻1 peaks and to their broadening. This suggests an intensification of the disorder within the cation sublattice. Following annealing at 450 °C in a vacuum, an increase in the intensity of the peaks at 450 cm⁻1 and 560 cm⁻1, as well as the Boson peak, was observed. We attribute these changes to the increased formation of Zn–N–Sn bonds within the film structure due to the ordering of the anion (nitrogen) sublattice. However, zinc and tin atoms still occupy random positions in their sublattices, contributing to the overall increase in structural disorder.

Nanoparticles of ZrO2:xSr2+ produced by the sonochemical method: Structural, morphological, and photoluminescent characterization for optoelectronic applications

The pursuit of efficient materials for technological applications is essential. Among these materials, zirconia emerges as a promising candidate with potential for several applications, from applications related to mechanical resistance to optoelectronic applications. By introducing dopants into this compound, it becomes feasible to modulate its inherent properties. In this study, ZrO2 doped with strontium was synthesized for the first time via the sonochemical method at different percentages in mol (1, 2, 4, and 8 mol%). Analysis via X-ray diffraction (XRD) and Raman spectroscopy unveiled the formation of both monoclinic and tetragonal phases, with the latter being stabilized through the incorporation of the dopant element. In addition to observing irregular morphology through scanning electron microscopy (SEM-FEG), a reduction in particle size was also evidenced following the introduction of Sr2+ ions, a phenomenon corroborated via Rietveld refinement. The reflectance spectra of the doped samples exhibited an optical absorption tail characterized by the Urbach energy (EU), indicating an increase in structural disorder in the samples. The photoluminescence (PL) results indicated that the introduction of Sr2+ ions into the ZrO2 matrix induced modifications in the characteristics of the spectrum profile. The phase transformation observed in XRD was reflected in the changes observed in the photoluminescent behavior of the samples, which emitted light between the blue and green regions.

ICEMS Characterization of NixFe3-xO4 (0.7 ≤ x ≤ 1.7) thin films grown by ion beam sputtering on (0001) Al2O3 substrates

We report here on the ICEMS characterization of nickel ferrite (NixFe3−xO4) thin films having different nickel contents grown on alumina substrates by Ion Beam Sputtering. The spectra corresponding to the films with nominal x = 0.7, 1.0 and 1.2 are characteristic of compounds crystallizing in a spinel-related structure showing two different magnetic sextets associated with Fe3+ located in the tetrahedral and octahedral sites of such structure. The spectra show an additional broad third sextet with a large isomer shift which suggests the occurrence of electron hopping between Fe2+ and Fe3+ ions sitting in the octahedral sites. With increasing nickel content, the linewidth of the sextets increases and their corresponding hyperfine magnetic fields decrease. This is an indication of an increase in structural disorder in the deposited films as their nickel concentrations increase. The cation distribution of the iron ions over the tetrahedral and octahedral sites appears also to depend on the nickel content. The film with x = 1.2 shows a significant increase in the fraction of octahedral iron ions as compared with the expected nominal value suggesting that, for this composition, some Ni2+ could also occupy tetrahedral sites. The Mössbauer spectrum corresponding to the film with x = 1.7 shows a magnetic pattern with very broad lines similar to those shown by amorphous or disordered materials. The average isomer shift is quite high (around 0.40 mms− 1) and characteristic of Fe3+ in octahedral oxygen coordination. This indicates that for the largest nickel content studied (x = 1.7), the film does not contain Fe3+ in tetrahedral environments suggesting that the spinel structure is no longer present. This correlates well with the X-Ray Diffraction data which indicate a structural change from spinel to a disordered rock-salt structure for this particular film with high nickel content.

Elinvar-Like Effect Induced by High Lattice Distortion in Zr 6 Ta 2 O 17 Ceramics

Super strength and toughness, excellent deformation resistance, and high-temperature service performance are the key factors to determine the practical application of new thermal barrier coatings (TBCs). The limited mobility of dislocations and the internal inherent defects in ceramics will inevitably lead to the decline of strength–plasticity and the reduction of service performance. Introducing preexisting twin boundaries and stacking faults (SFs) or preparing ceramic materials with high configuration entropy has demonstrated to be an effective strategy for enhancing the mechanical properties of ceramics. However, due to the positive thermal expansion coefficient of most ceramics and the remarkable increase of structural disorder at elevated temperature, the problem of elastic softening has become a bottleneck restricting the high-temperature service life of new TBCs. In this paper, the deformation behavior of high configuration entropy Zr 6 Ta 2 O 17 ceramics at 25 to 1,200 °C was in situ monitored via digital image correlation technique and three-point bending test platform in high-temperature environment. A remarkable Elinvar-like effect appears in the Zr 6 Ta 2 O 17 ceramic. More interestingly, mechanical deformation dominates the severe lattice distortion (deformation twins, SFs) and the disorder–order transition of chemical order at the atomic scale, while temperature can further enhance the degree of lattice distortion and ordering of Zr 6 Ta 2 O 17 ceramics. Furthermore, the atomic fluctuations at high temperature promotes the comprehensive improvement of mechanical properties in the Zr 6 Ta 2 O 17 ceramics.

Study of Structure, Morphology and Optical Properties of Cobalt-Doped and Co/Al-co-Doped ZnO Thin Films Deposited by Electrospray Method

A versatile electrospray method was utilized for deposition of thin ZnO films doped with Co (5%) (CZO) or co-doped with Co (2.5%) and Al (2.5%) (CAZO). Thin polycrystalline films with approximate thickness of 200 nm and high transmittance (more than 80%) were obtained. No additional XRD peaks due to dopant impurities or dopant oxides were observed. The cobalt doping led to decrease in grain size and increase in crystallite size from 22 nm to 29 nm in the (101) direction. Smaller changes were observed for the CAZO films. Surface roughness of the films was measured using a 3D optical profiler. Surface roughness of the doped films was from 5 nm to 9 nm higher than that of the pure films. Refractive index, extinction coefficient and thickness of the films were calculated using ellipsometric measurements and were further used for determination of optical band gap and Urbach energy. Refractive index and optical band gap increased with doping from 1.86 and 3.29 eV for pure ZnO to 2.00 and 3.35 eV for CZO and 1.97 and 3.33 eV for CAZO films. Through calculation of Urbach energy (119 meV for pure ZnO, 236 meV for CZO and 138 meV for CAZO), it was demonstrated that doping leads to an increase in structural disorder, most pronounced in the case of Co doping.

Formation of ZnO films on SiC/porous Si/Si substrates

Reactive magnetron sputtering was used to obtain ZnO films on SiC/porous Si/Si substrates. The silicon carbide film on the surface of porous Si was obtained using chemical substitution of atoms. It has been shown that ZnO films grown at the partial oxygen pressure 0.6 Pa are characterized by a smoother and more uniform surface than coatings grown at the oxygen pressure 0.1 Pa. Being based on the analysis of Raman and photoluminescence spectra, it has been shown that the increase in partial pressure of oxygen leads to the increase in structural disorder of the ZnO crystal lattice, on the one hand, and at the same time to a decrease in the concentration of intrinsic defects, including ionized oxygen vacancies Oi, on the other hand.

Thermal effects of the excitation laser power on carbonaceous meteorite Northwest Africa 6603 by Raman spectroscopy: an undergraduate research project

Raman spectroscopy has been used extensively on meteoritic samples since it is a nondestructive tool that provides information about their structure and mineralogical composition, which can give important clues about planet formation. However, the power of the excitation laser used in this technique can alter the properties of the samples due to thermal effects. In this undergraduate research work, the laser-induced thermal effects produced on the carbonaceous chondritic meteorite Northwest Africa 6603 were studied in detail by analyzing the low- and high-resolution Raman spectra parameters of the minerals found in the inclusions and matrix of this sample as a function of the excitation power. Olivine (forsterite), graphitic carbon, pyroxene (enstatite), hematite and gehlenite were the minerals identified in the studied regions. The Raman parameters of these minerals were affected by the laser power to a greater or lesser extent, indicating an increase in structural disorder. In general, the alterations observed were permanent (reverse changes were not observed). These thermal effects were correlated with the topography of the irradiated regions by analyzing their changes using optical microscopy. The micrographs of a few regions showed changes on their topography after irradiating the regions with the maximum applied power (e.g., more depressed areas). These findings exhibited strong evidence of the thermal effects induced by the laser power on the materials found in this fragment, which must be considered to avoid alterations of the physical and chemical properties of the meteoritic samples. In addition, this work presents the first study done on the mineralogical composition of Northwest Africa 6603 using Raman spectroscopy. Furthermore, from an educational standpoint, this project exposed the involved undergraduate physics students to numerous research steps (e.g., experiment preparation, data acquisition/analysis, and manuscript preparation) which provided them with a broad spectrum of valuable scientific and technical tools for their future careers.

Effects of Zr addition on electrochemical characteristics of MgTiMnNi hydrogen storage alloys

The electrochemical hydrogen storage properties of 25 h milled Mg0.80Ti0.175Mn0.025ZrxNi1-x (x = 0, 0.025, 0.05, 0.1) quinary alloys were investigated. The substitution of Zr for Mg or Ni leads to an increase in structural disorder and amorphization. Thus, the maximum discharge capacity and the cycling stability of MgNi-based alloys can be enhanced. The x-ray diffraction patterns indicate that all additive elements are entirely dissolved in the synthesized alloys, and amorphous structure was successfully obtained by 25 h milling. Among the milled alloys, the Mg0.80Ti0.175Mn0.025Zr0.10Ni0.90 alloy exhibited the best discharge capacity of 604 mA h g−1 at the initial charge/discharge cycle. The obtained results demonstrate that using multi-component compositions is beneficial for enhancing the structural and cyclic stability of MgNi-based alloys. Therefore, substituting additive elements for Mg or Ni may offer impressive performance for efficient hydrogen storage applications.

Cellulose-based carbon membranes for gas separations - Unraveling structural parameters and surface chemistry for superior separation performance

Carbon molecular sieve membranes were prepared from the carbonization of a cellulose-based polymeric precursor doped with urea. The addition of urea to the cellulose precursor induces an increase in structural disorder and an increase in pore volume inside the structure of prepared membranes. This unique preparation procedure proved to be an extremely effective method for tuning the pore size of carbon membranes to the desired separations. Urea acts as a pore-forming agent that allows the fabrication of carbon membranes with high porosity. The addition of 2.8 wt% of urea doubled the permeability of the prepared carbon membrane to hydrogen. In addition, a permeability to oxygen of 333 barrer was obtained, without impairing the selectivity. The proposed preparation procedure is compatible with industrial production and scaling, hopefully making carbon membranes a viable solution to produce oxygen-enriched air, recovering of hydrogen from hydrocarbon streams and carbon dioxide removal from natural gas/biogas.

Enhanced energy storage performance of Bi0.5Na0.5TiO3-based ceramics via grain tuning and relaxor construction

Relaxor ferroelectrics have become competitive candidates in energy storage applications owing to their relatively high maximum polarization, high breakdown strength, and relatively low remnant polarization. Here, Bi0.5Na0.5TiO3 (BNT) with large polarization was selected as the base composition, and Sr0.7Bi0.2Ti0.8Hf0.2O3 (SBTH), as a dopant, was added into BNT to improve its relaxor behavior and decrease the grain size. A series of (1-x)Bi0.5Na0.5TiO3-xSr0.7Bi0.2Ti0.8Hf0.2O3 (abbreviated as (1-x)BNT-xSBTH, x = 0.1, 0.2, 0.3 and 0.4) ceramics were synthesized. The addition of SBTH resulted in the increase in structural disorder, as confirmed by the red-shift in Raman spectra, the enhancement of the relaxor characteristic and the fast response of the domains in local poling measurements. As a result, excellent energy storage properties (with the recoverable energy storage density of 5.5 J/cm3 and efficiency of 85.9 % at 410 kV/cm) were realized in the 0.6BNT-0.4SBTH sample. Moreover, the sample also exhibited excellent thermal stability (20 °C to 200 °C) and frequency insensitivity (0.5–500 Hz). These results suggest that BNT-based relaxor ferroelectric ceramics modulated by SBTH possess great potential in dielectric energy-storage capacitors.

Effects of Grain Refinement and Thermal Aging on Atomic Scale Local Structures of Ultra-Fine Explosives by X-ray Total Scattering.

The atomic scale local structures affect the initiation performance of ultra-fine explosives according to the stimulation results of hot spot formation. However, the experimental characterization of local structures in ultra-fine explosives has been rarely reported, due to the difficulty in application of characterization methods having both high resolution in and small damage to unstable organic explosive materials. In this work, X-ray total scattering was explored to investigate the atomic scale local distortion of two widely applicable ultra-fine explosives, LLM-105 and HNS. The experimental spectra of atomic pair distribution function (PDF) derived from scattering results were fitted by assuming rigid ring structures in molecules. The effects of grain refinement and thermal aging on the atomic scale local structure were investigated, and the changes in both the length of covalent bonds have been identified. Results indicate that by decreasing the particle size of LLM-105 and HNS from hundreds of microns to hundreds of nanometers, the crystal structures remain, whereas the molecular configuration slightly changes and the degree of structural disorder increases. For example, the average length of covalent bonds in LLM-105 reduces from 1.25 Å to 1.15 Å, whereas that in HNS increases from 1.25 Å to 1.30 Å, which is possibly related to the incomplete crystallization process and internal stress. After thermal aging of ultra-fine LLM-105 and HNS, the degree of structural disorder decreases, and the distortion in molecules formed in the synthesis process gradually healed. The average length of covalent bonds in LLM-105 increases from 1.15 Å to 1.27 Å, whereas that in HNS reduces from 1.30 Å to 1.20 Å. The possible reason is that the atomic vibration in the molecule intensifies during the heat aging treatment, and the internal stress was released through changes in molecular configuration, and thus the atomic scale distortion gradually heals. The characterization method and findings in local structures obtained in this work may pave the path to deeply understand the relationship between the defects and performance of ultra-fine explosives.

Structure disorder observation of fluoropolymers composed of vinylidene fluoride and tetrafluoroethylene in supercritical CO2 using time-resolved small- and wide-angle X-ray scattering

Fluoropolymers have a growing range of applications in many industries. Neat fluoropolymers and fluorinated copolymers were prepared via the suspension polymerization method with entire mass ratio of vinylidene fluoride (VdF) and tetrafluoroethylene (TFE). Supercritical CO2 was applied as a fluid stimulus to the fluoropolymers. An increase in structural disorder was investigated using time-resolved small-angle X-ray scattering (SAXS). The SAXS change induced by the stimulus proceeded more slowly with increasing VdF ratio of the copolymer, suggesting that the higher VdF content contributes to the tolerance of microvoid formation and the corresponding onset of breakdown in the polymer material. The degree of crystallinity of the fluoropolymers was evaluated using wide-angle X-ray scattering, showing the degree of crystallinity was similar before and after the stimulus. Time-resolved and in-situ SAXS/WAXS measurements were carried out on the copolymer with a ratio of VdF:TFE = 8:2 as the copolymer having the highest VdF content studied here.

Microstructure dependent chemo-mechanical behavior of amorphous Si anodes for Li-ion batteries upon delithiation

Alloying-type anodes exhibit the solid-state amorphization during charging/discharging cycles. The mechanical and electrochemical properties of amorphous reaction phases have been widely explored recently. However, there is still lack of understanding of the underlying mircostructure-property relation in the delithiation behavior of alloying anodes. Here we perform molecular dynamics simulations to investigate the microstructure effect on the chemo-mechanical properties of amorphous Si ( a -Si) anodes upon delithiation. It is indicated that stress-free delithiation without sufficient structural relaxation leads to the gradual accumulation of structural disorder (the increase of excess energy) in amorphous Li-Si systems ( a -Li x Si). The creation of structural disorder during delithiation not only facilitates the plastic deformation of a -Li x Si at lower stress, but also thermodynamically destabilizes a -Li x Si associated with the drop of open-cell potentials. While upon constrained delithiation, the initial value of excess energy and reaction stress both contribute to the increase of structural disorder during delithiation process. Based on the stress-dependent chemical-potential model, the tensile stress increases open-cell potentials, and reduces the Li chemical potential which weakens the driving force for delithiation. As a result, the structural disorder and tensile reaction stress may cause the undesirable capacity fading of a -Si anodes, and is detrimental to the battery performance. • The delithiation behavior of amorphous Si anodes is simulated by MD simulations. • The structural disorder in amorphous Si is quantified by excess energy. • The effect of structural disorder on the chemo-mechanical properties is explored.

INCORPORATION OF Mo6+ IN FERRIHYDRITE, GOETHITE, AND HEMATITE

Among all iron oxides, hematite (α-Fe2O3), goethite (α-FeOOH), and ferrihydrite (FeOOH⋅nH2O) are the most common mineral species. While immobilization of Mo6+ by surface adsorption on ferric oxides has been studied extensively, the mechanisms of incorporation in their structure have been researched little. The objective of this study was to investigate the relation between Mo content and its structural incorporation in hematite, goethite, and six-line ferrihydrite by a combination of X-ray absorption spectroscopy (XAS), powder X-ray diffraction (pXRD), and inductively-coupled plasma optical emission spectrometry (ICP-OES). Synthesized in the presence of Mo, the hematite, goethite, and six-line ferrihydrite phases incorporated up to 8.52, 0.03, and 17.49 wt. % Mo, respectively. For hematite and goethite, pXRD analyses did not indicate the presence of separate Mo phases. Refined unit-cell parameters correlated with increasing Mo concentration in hematite and goethite. The unit-cell parameters indicated an increase in structural disorder within both phases and, therefore, supported the structural incorporation of Mo in hematite and goethite. Analysis of pXRD measurements of Mo-bearing six-line ferrihydrites revealed small amounts of coprecipitated akaganéite. X-ray absorption near edge structure (XANES) measurements at the Mo L3-edge indicated a strong distortion of the MoO6 octahedra in all three phases. Fitting of extended X-ray absorption fine structure (EXAFS) spectra of the Mo K-edge supported the presence of such distorted octahedra in a coordination environment similar to the Fe position in the investigated specimen. Incorporation of Mo6+ at the Fe3+-position for both hematite and goethite resulted in the formation of one Fe vacancy in close proximity to the newly incorporated Mo6+ and, therefore, charge balance within the hematite and goethite structures.

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

The upper critical field sets the thermodynamic limit to superconductivity. A big gap is present between the upper-critical-field values measured in MgB2 polycrystalline bulk superconductors and those of thin films, where values as high as ~ 50 T have been achieved at 4.2 K. Filling this gap would unlock the potential of MgB2 for magnet applications. This work presents the results of an extensive experimental campaign on MgB2 bulk samples, which has been guided by a Design of Experiment. We modeled the dependence of the upper critical field on the main synthesis parameters and established a new record (~ 35 T at 4.2 K) preparing C-doped bulk samples by a non-conventional rapid-synthesis route. This value appears to be an upper boundary for the upper critical field in bulk samples. Structural disorder in films seems to act selectively on one of the two bands where superconductivity in MgB2 takes place: this enhances the upper critical field while reducing the critical temperature only by few Kelvins. On the other hand, the critical temperature in bulk samples decreases monotonically when structural disorder increases, and this imposes a limit to the maximum achievable upper critical field.

Urea and surfactant assisted hydrothermal growth of ceria nanoparticles

Cerium oxide nanoparticles were prepared via a modified hydrothermal approach to reduce the reaction durations in the conventional hydrothermal route. Urea and NaOH were used together for the fast growth of ceria nanocubes within a short reaction period. The formation of Ce-O-Ce bonds to grow CeO2 nuclei with the help of urea, and the anisotropic growth in the base medium led to the formation of nanocube morphology. Cetyltrimethylammonium bromide (CTAB) was added further in the precursor solution as a capping and structure directing agent that directed the growth of ceria nanostructures from spherical to irregular polygonal morphology. Ceria nanocubes of 18−20 nm sizes with highly reactive (1 0 0) faces were formed after hydrothermal reaction. On the other hand, CTA+ group reduced the particle sizes to 8−10 nm with the (1 1 1) exposed stable faces. In addition, ceria nanostructures obtained with the assistance of surfactants show intrinsic oxygen vacancies and enhanced concentrations of Ce3+ in cubic fluorite structure. Furthermore, band gap and Urbach energy calculations show that the increase in structural disorder and contribution of the defects in ceria morphologies of the order: nanocubes < nanoplates < polygonal nanostructures < nanospheres. The present research indicated a novel approach to synthesize ceria nanoparticles within short reaction durations.

Direct Observation of Electrochemically Active Fe3+/Fe4+ in LiCo0.8Fe0.2MnO4 By in Situ Mössbauer and in Situ X-Ray Absorption Spectroscopy

The usage of Fe at high oxidation states might be interesting for increasing the energy density of Li-ion batteries and also for substituting expensive/toxic elements in the cathode materials. The redox activity of Fe3+/Fe4+ in the spinel LiCo0.8Fe0.2MnO4 has been investigated via in situ Mössbauer spectroscopy and in situ X-ray absorption spectroscopy (XAS) during electrochemical cycling in a complete Li battery cell [1]. The initial Mössbauer spectrum consists of a doublet with isomer shift IS = 0.330(1) mm/s and quadrupole splitting QS = 0.722(1) mm/s (Fig. 1). These parameters are characteristic of Fe3+ in a high-spin state on the octahedral sites of the spinel structure. In the beginning of the charging process vs. Li+|Li, a broadening of this doublet can be observed. This corresponds to an increased electric field gradient at the site of the Fe nuclei, i.e. an increase of structural disorder around the Fe ions, and is probably cause by the initial oxidation of Co. During further charging, the Fe3+ doublet successively disappears and is replaced by a new narrow doublet with isomer shift of -0.134(6) mm/s. This negative value clearly reveals that Fe4+ is formed. Further cycling between 5.3 V and 4.3 V reveals that this oxidation is highly reversible. The XAS spectra acquired during charging of LiCo0.8Fe0.2MnO4 vs. Li+|Li clearly show a shift of the Fe K absorption edge towards higher binding energies and thus an oxidation of Fe3+ to Fe4+. The XAS spectra acquired during discharging show again that this process is fully reversible. In summary, the reversible formation Fe4+ was clearly observed by both methods, hence proving the electrochemical activity of Fe at voltages above 5 V vs. Li+/Li. This enables future research on new environmentally benign and inexpensive electrode materials with operating voltages above 5 V and thus an increased energy density. [1] Observation of Electrochemically Active Fe3+/Fe4+ in LiCo0.8Fe0.2MnO4 by in situ Mössbauer Spectroscopy and X-Ray Absorption Spectroscopy, C. Dräger, F. Sigel, R. Witte, R. Kruk, L. Pfaffmann, V. Mereacre, M. Knapp, H. Ehrenberg, S. Indris, Phys. Chem. Chem. Phys. 21, 89-95 (2019).

Optical constants of Ge-Sb-Se-I chalco-halide glasses using a single reflectance spectrum

Chalco-halide glasses possess a low weak absorption tail in the atmospheric IR windows. They have improved optical properties, particularly broadening the mid-infrared cutoff. In this work, we report the synthesis of iodine doped Ge25Sb10Se65-xIx (x = 0, 4, 8, 12, 16) system. The optical behaviour has been analysed using a single reflection spectrum. The reflection spectrum has been obtained using an ultraviolet-visible-near-infrared spectrophotometer for wavelength 400 nm–2500 nm. The static refractive index has shown an increase from 2.76 (x = 0) to 3.33 (x = 16). The dispersive behaviour is found to be normal for all samples. The values of the Urbach energy show an increase in structural disorder. A decrease in the optical band gap has been observed with the addition of iodine amount. The third-order non-linear optical susceptibility obtained from semi-empirical method increases with the iodine content.

Effect of IR laser radiation on the structure and optical properties of PC-PBT/Pd polymer nanocomposite films

ABSTRACTBayfol (PC-PBT blend film) is a class of polymeric solid-state nuclear track detector which has a lot of applications in several radiation detection fields. It is a bisphenol-A polycarbonate PC blended with polybutylene terephthalate PBT. Bayfol/Palladium (PC-PBT/Pd) nanocomposite films have been deposited using the molding technique. It is worth mentioning that this report is almost the first one dealing with the topic of the changes of physical properties of Bayfol/Pd nanocomposite due to laser exposure. Samples from PC-PBT/Pd (5 wt%) nanocomposite were exposed to IR-pulsed laser of 5-W power, capable of producing 2000 pulses per second with pulse duration of 200 ns at 904 nm. The laser fluences were in the range 2–25 J/cm2. The resultant modifications in the exposed nanocomposite samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction (XRD), UV spectroscopy and color difference studies. The results indicate the proper dispersion of Pd nanoparticles in the PC-PBT matrix that causes a strong intermolecular interaction between Pd and PC-PBT, resulted in an increase in refractive index and the amorphous phase. Also, it is found that the laser exposure reduces the optical energy gap that could be attributed to the increase in structural disorder of the exposed PC-PBT/Pd nanocomposites due to crosslinking. Further, the color intensity ΔE, which is the color difference between the exposed samples and the non-exposed one, was increased with increasing the laser fluence, convoyed by a significant increase in the green and yellow color components.