Crystallinity Research Articles

Intriguing photophysical and mechanochromic characteristics of carboline-based benzothiadiazole donor‒acceptor triad compounds

Three novel carboline-based benzothiadiazole compounds, αCB, βCB, and γCB, bearing α-, β-, and γ-carboline, respectively, were synthesized and characterized. The molecular structures of αCB and γCB in the crystalline state were analyzed using single-crystal X-ray diffraction. The UV–vis absorption and photoluminescence spectra of all compounds displayed typical intramolecular charge transfer (ICT) characteristics, resulting in clear solvatochromic effects in various organic solvents. Theoretical calculations also verified that the major electronic transitions of the three compounds could be assigned to the ICT transition between the carboline moiety (as the electronic donor, D) and benzothiadiazole center (as the acceptor, A). The unit cell of the crystal structure of αCB revealed two solvent (chloroform) molecules residing in the space between the two α-carboline moieties via hydrogen bonding, which could inhibit the structural fluctuation of this compound. Given this feature, αCB demonstrated higher emissive efficiency and a lower nonradiative decay process compared with βCB and γCB. Interestingly, the crystalline powders of αCB, including the solvent molecules in its unit cell, demonstrated a high-contrast and reversible mechanochromic phenomenon, which originated from the conversion of the compound from a crystalline state to a randomly aggregated one. The above findings provide insights into the molecular design of carboline-based D‒A‒ D-type organic fluorophores with high emissive efficiency and intriguing functional characteristics.

Kromatografi Lapis Tipis (KLT): Pendekatan Pola Kromatogram Untuk Mengkonfirmasi Rhodamin B Pada Perona Pipi

Blusher is a decorative cosmetic whose purpose is to beautify the face and emphasize the shape of the cheekbones. Rhodamine B is a synthetic dye in the form of a crystalline powder which is prohibited from being used in cosmetics according to the regulation by Head of The Indonesian Food and Drug Administration No. 18 of 2015 concerning Technical Requirements for Cosmetic Materials, because they are dangerous if contact with the skin. The purpose of this study was to determine rhodamine B in blusher which is traded in Kandat Market, Kediri Regency. In this study, five samples were used, namely sample A, sample B, sample C, sample D, and sample E. The qualitative analysis method used was Thin Layer Chromatography (TLC). In this method, the eluent N-butanol:ethyl acetate:ammonia is used in the ratio (55: 20: 25). TLC results showed visually in pink color, then when viewed under UV light 254 nm was yellow fluorescence. From the five samples, the Rf value was 0.52; 0.56; 0.61; 0.52 and 0.57, while the average Rf of the standard solution of rhodamine was 2.1. So that from the five samples it can be seen that they do not contain rhodamine B dye.

Fly Ash Epoxy Composites with Superior Fire Retardant Properties

Epoxy was loaded with varying concentrations of fly ash and was characterized for its structural properties using XRD and SEM. The XRD results revealed reduction of crystallinity with increase in filler content indicating that the composites are semi crystalline in nature. The SEM images showed that at lower concentration of filler content, fly ash is uniformly distributed within the epoxy and at higher concentrations of fly ash, agglomerates were observed. Mechanical properties such as tensile and compressive properties were estimated and the results showed that, the composites exhibit enhanced tensile strength and compressive strength for epoxy with 20 wt% fly ash. Flammable properties such as heat release rate, peak heat release rate, time to ignition, CO and CO2 yields are estimated and reported. Decrease in combustion time, peak heat release rate, time to ignition, CO and CO2 yields with increase in filler content clearly indicates the superior flammability performance of epoxy composites loaded with fly ash.

Optimization of obtaining of translucent luminescent ceramics YNbO4 by uniaxial hot pressing from crystal powders synthesized by sol-gel

We have established optimized parameters of technological process for obtaining of translucent luminescent YNbO4 ceramics by uniaxial hot pressing (UHP). Ultrafine crystalline powders used for this have been synthesized by sol-gel and sintered at three different temperatures. Series of ceramic YNbO4 samples were obtained from the powders by UHP at three different sintering conditions. Morphological features of the microstructure, mechanical and photoluminescent characteristics in the visible wavelength range have been compared for YNbO4 ceramic samples obtained at different UHP conditions and controlled with sample prepared by conventional sintering (CS). The most optimal UHP regime for translucent YNbO4 ceramics obtaining have been chosen.

Synthesis and structural characterization of nanocrystalline silicon by high energy mechanical milling using Al2O3 media

High energy mechanical milling was used to fabricate nanoparticulate Si using Al2O3 grinding media. Two ratios of grinding media to charge of 5 and 10 were used with milling times, such as 7, 10, 13, 16, and 19 h. Morphology of the milled powders was investigated by scanning and transmission electron microscopy. Crystallinity of the milled powders was found to be preserved for all milling conditions without amorphization. Crystallite size of the milled powders was calculated from x-ray diffractograms by various methods. From morphology and crystallite size it was observed that 13 h of milling is the optimum time to produce well dispersed Si nanoparticulates. Further increase in milling duration clearly indicated agglomeration of the powders and cold welding of the crystallites for samples of both media-to-charge ratios. X-ray diffractograms and Raman spectrographs of the milled samples were used to calculate the strain induced in the materials, which indicated progressive increase in strain with milling duration. The results indicate that Al2O3 milling media can be used with optimized process conditions for the production of large quantities of nanoparticulate Si.

Accuracy Limits of Pair Distribution Function Analysis in Structural Characterization of Nanocrystalline Powders by X-ray Diffraction

We report the minimum errors of structural parameters, namely lattice parameter, crystallite size, and atomic displacement parameters, expected from Pair Distribution Function (PDF) analysis of nanocrystalline gold powders for the first time by a self-consistent computational methodology. Although PDF analysis has been increasingly used to characterize nanocrystalline powders by X-rays, the current literature includes no established error bounds to be expected from the resulting structural parameters. For accurate interpretation of X-ray diffraction data, these error bounds must be determined, and the obtained structural parameters must be cleared from them. Our novel methodology includes: 1) simulation of ideal powder diffraction experiments with the use of the Debye scattering equation, 2) pair distribution function analysis of the diffraction data with the Diffpy-CMI analysis software, and 3) determination of the errors from PDF analysis of the simulated diffraction data by comparing them with real-space analysis of spherical gold nanocrystals that are 30 nm size and smaller. Our results show that except for the lattice parameters and even with an ideal crystalline powder sample and ideal diffraction data, the extracted structural parameters from PDF analysis diverge from their true values for the studied nanopowder. These deviations are dependent on the average size of the nanocrystals and the energy of the X-rays selected for the diffraction experiments, where lower X-ray energies and small-sized nanocrystalline powders lead to greater errors.

Hierarchically Porous Poly(ionic liquid) - Organic Cage Composite Membrane for Efficient Iodine Capture.

The effective capture of iodine with high volatility and poisonousness is significant for reprocessing the spent nuclear fuel. In this article, we report a hierarchically porous poly(ionic liquid)-organic cage composite membrane (PIL@CC3) possessing a gradient content distribution of CC3 cage crystals throughout the membrane to capture iodine vapor. The introduction of microporous CC3 can significantly enhance the uptake capacity of iodine up to 980 mg g-1 , which is superior to that of a pristine PIL membrane carrying large meso- and macropores (99 mg g-1 ), and CC3 crystalline powder (662 mg g-1 ). Such enhanced performance benefits from the micro-meso-macroporous structure of the PIL@CC3 membrane in which the large meso- and macropores facilitate the mass transfer of iodine molecules from the external environment into the surface of the CC3 crystal, followed by diffusion of iodine molecules from the CC3 surface into the interior and exterior pores of the CC3 crystal. In addition, the asymmetric distribution of CC3 crystals across the PIL@CC3 membrane also displays its advantage in intercepting trace iodine, revealing its great potential for practical application. This study provides an idea for constructing hierarchically porous membrane composites for the removal of toxic vapors.

Application of Foam Glass-Ceramic Composite Thermal Insulation Material in Traditional Buildings

In order to solve the application of thermal insulation materials in traditional buildings, a foam glass-ceramic composite thermal insulation material was proposed for the application of traditional buildings. First, the preparation of the hydrated glass matrix was completed by using the colloidal chemical method with sodium water glass, boric acid, calcium bentonite, and fly ash as the main raw materials. Second, using the introduction of crystalline mineral powder fly ash and secondary heat treatment, a low-temperature foam glass-ceramic composite material with lightweight, high strength, good water resistance, and low cost is prepared. Finally, the process parameters such as dehydroxylation heat treatment temperature and holding time involved in the preparation process were explored and optimized. It is proved that the external content of fly ash is 20 wt.% and above, and the external content of boric acid is 1-2 wt.%. The mixed sol has a bulk density of 192–256 kg/m2, a compressive strength of 0.44–0.63 MPa, a weight loss rate of 5.1–7.8 wt%, and a softening coefficient of 0.85–0.95, and thermal conductivity is 0.056–0.064 W/(m·K).

Investigation on the effect of vacuum annealing time on structural and optical properties of YAG:Ce nanoparticles prepared by mixed-fuel microwave solution combustion synthesis

Cerium doped yttrium aluminum garnet (YAG:Ce) nanoparticles were synthesized via mixed-fuel microwave solution combustion synthesis and further optimized by post annealing treatment. The effects of vacuum annealing time and ambient on the phosphor structural, morphological, compositional, and optical properties were investigated in detail. The structural study performed with X-ray diffraction analysis and Rietveld refinement revealed a direct crystallization from amorphous into single phase YAG:Ce was achieved at 1050 °C for 1 h. The increase in annealing time enhances the powder crystallinity and promotes crystal growth to form larger particles (50–85 nm). However, prolonged annealing would cause the partial oxidation of Ce3+ into optically inert Ce4+ ions, which was likely due to the increased Ce segregation. X-ray photoelectron spectroscopy evidenced that vacuum annealing has a higher tendency to suppress Ce3+ oxidation in comparison to air annealing, resulting in a significant enhancement of photoluminescence emission intensity by 20%. The optimum emission intensity was obtained for YAG:Ce nanoparticles after 5 h of vacuum annealing treatment with color coordinates of (0.391, 0.569). The white light emitting diode (WLED) fabricated with the optimized YAG:Ce nanoparticles showed a cool-white light with a maximum luminous efficacy of radiation of 285 lm/W and a corresponding color rendering index of 83.

Exploration of Fulvic Acid as a Co-Former in Crystal Engineering

The aim of the project was to investigate Peat-derived Fulvic acid for its propensity to form co-crystals with quercetin and curcumin and characterize it by using different analytical techniques. The formation of co-crystals generally enhances water solubility and the overall bioavailability of molecules. Co-crystals were synthesized using a 1:1 stoichiometric ratio of fulvic acid with quercetin and curcumin, respectively, using solvent crystallization techniques taking tetrahydrofuran and water in a 1:1 v/v ratio. The co-crystals were characterized by spectroscopic methods, FTIR and Differential scanning calorimetry. Further confirmation was made by morphological studies using SEM. A structural analysis was also carried out, using 13C solid-state NMR analysis. The studies confirmed the formation of semi crystalline forms. Furthermore, the saturation solubility displayed the enhancement in solubility of up to 10, 5-folds for Quercetin and Curcumin, respectively. The in vitro dissolution results showed that T50% was achieved within 30 min for both the drugs. The literature supports that the nutraceutical co-crystals offer advantages, particularly in the improvement of biopharmaceutical properties and addressing the challenges of the lab and manufacturing scale process. Both the semi crystalline powders exhibited enhanced solubility and a better dissolution profile.

Superfast crystalline powder synthetic strategy toward scale-up of perovskite solar cells

Commercialized perovskite solar cells (PSCs) are limited owing to the high cost of high-purity PbI2 (99.999%), raw material batch variance, and stoichiometric deviation. Here, we report a rapid antisolvent-assisted crystallization (RAC) method to speedily obtain high-grade perovskite powders from low-purity and inexpensive PbI2 (98%) raw materials. Without long-term stirring or employing any toxic antisolvent, RAC is a cost-efficient and environmentally friendly method with a high yield of over 92%. By precise characterization, the RAC method can reduce the impurities in raw materials that minimize the impurity-induced shallow-level trap density and hence the non-radiative recombination of carriers. As per the results, over 12% increase in power conversion efficiency (PCE) is obtained from low-grade raw materials, resulting in a champion PCE of 20.5% for small-area MAPbI3 PSCs and certified 18.35% for doctor-bladed 6.75-cm2 mini-module. With a reduction in material cost and a considerable increase in efficiency, RAC is a suitable alternative to the mass-produced, commercially available large-scale PSC.

The Benefit of the Glassy State of Reinforcing Particles for the Densification of Aluminum Matrix Composites

In metallic glass-reinforced metal matrix composites, the glassy phase can serve a dual purpose: (i) it can behave as soft binder and porosity remover during consolidation; and (ii) it can act as the hard reinforcing phase after densification. The present work aimed to demonstrate the benefit of the glassy reinforcing particles for the densification of aluminum matrix composites. The consolidation behavior of Al–50 vol.% Fe-based alloy mixtures prepared using a glassy Fe66Cr10Nb5B19 alloy powder (Tg = 521 °C, Tx = 573 °C) or a crystalline Fe62Cr10Nb12B16 alloy powder was studied under spark plasma sintering (SPS) and hot pressing (HP) conditions. The powders were consolidated by heating above the glass transition temperature of the glassy alloy (up to 540 °C in SPS and 570 °C in HP). When the coarse aluminum powder was used, the reinforcing particles formed chains within the microstructure. In composites formed from the fine Al powder, the particles of the Fe-based alloy were separated from each other by the metallic matrix, and the tendency to form agglomerates was reduced. The glassy state of the alloy was shown to be beneficial for densification, as the metallic glass acted as a soft binder. The densification enhancement effect was more pronounced in the case of reinforcing particles forming chains. The hardness of the Al–50 vol.% glassy Fe66Cr10Nb5B19 composites obtained by SPS was twice the hardness of the unreinforced sintered aluminum (110 HV1 versus 45 HV1).

Study of novel synthesized Gum-Arabic-Ammonium thiocyanate based polymer electrolyte for testing electrical properties and electrochemical sensing

The novel Gum Arabic-Ammonium Thiocyanate-based solid polymer electrolyte was synthesized using the solvent casting technique, which involved mixing Gum Arabic (GA) with ammonium thiocyanate (NH4SCN) in the presence of water. The different concentrations of NH4SCN admixture with the GA synthesized have been characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), dielectric, and ionic conductivity studies. The structural behavior (amorphous or semi crystalline, vibrational shifts), dielectric constant & dielectric loss behavior, relaxation time, and ionic conductivity response of various NH4SCN concentrations admixture on the GA have shown significant variation and the results are presented in detail. To make the batteries have a better ionic conductivity, the synthesized GA-NH4SCN sample, two cathode materials (MnO2(Cell I) and PbO2 + V2O5(Cell II)), and one anode material (Zn/ZnSO4·7H2O) have been taken for examining the open circuit voltage and discharge characteristics at different resistances as a function of time, and their results were discussed in detail.

Production of Xylitol from Corn Biomass using Candida sp. As Microbial Agent

Xylitol, C5H12O5, is a white and odorless crystalline powder of sweetening agents that included as low-calorie sweetener. It could be used as a healthy ingredient for food and pharmaceutical. Natural sources of xylitol are fruit and vegetable, even in minute quantities. At industrial scale, xylitol is produced through hydrolysis and hydrogenation process of lignocellulosic materials. The aim of this research was to study the production of xylitol from corn biomass using Candida sp. as a microbial agent. The research was conducted using different species of Candida sp. (C. guilliermondii and C. tropicalis) and supplement media growth (with or without glucose). Xylitol concentration was examined after fermentation for 3 and 5 days. The results showed that corncob is a promising material to use in producing xylitol from lignocellulosic biomass. The longer fermentation time, the higher xylitol concentration, ranged from 0.049 to 0.088 g/L. However, compare to another microbe species, the treatment using Candida tropicalis showed that long fermentation resulted in a lower xylitol concentration. The addition of glucose as co-substrate increased xylose consumption rate and xylitol productivity. These results provide useful information to develop further study about xylitol production using agricultural biomass.

Development of the experimental composition based on the mycelial fungi Fusarium sambucinum and evaluation of its efficiency as a means for the prevention of diarrhea in calves

The main task in livestock complexes is to ensure the safety of livestock and to obtain healthy young animals. It is known that in the last months of pregnancy in cows, the fetal weight increases by 70-75 %, all the organs of the immune defense and the enzymatic system develop, and, consequently, the general resistance of the newborn young is formed. This underlines the importance of creating optimal conditions for feeding and keeping pregnant animals. Therefore, when developing rational measures for the prevention and control of diseases of nascent young animals, it is necessary to consider this complex as a single system, since the physiological immaturity of newborns cannot be further compensated even by ideal growing conditions.The use of a composition based on a mycelial fungus and an organosulfur compound is a promising preventive agent that does not have a pronounced negative effect on the animal's body. The proposed therapeutic two -component composition for pregnant cows consists of selimaccide and a commercial preparation «Milife» containing a culture of the mycelial fungus Fusarium sambucinum strain VKPM F-139. Selimaccide is the diethylammonium salt of N-methylamino-1-phenylmethanesulfonic acid, belongs to the new chemical compounds of the class of aminomethanesulfonates, is a white crystalline powder with a specific odor, well soluble in water, alcohol, dimethylsulfoxide.Daily watering of the proposed composition to pregnant cows 12 days before calving 2 times a day at a dose of 500 cm3 / head with an interval of 6 to 8 hours ensures the birth of calves resistant to gastrointestinal disorders.The aim of the research was to study the effectiveness of the drug, which is a combination of selimaccide and the mycelial fungus Fusarium sambucinum strain VKPM F-139 as a means of preventing gastrointestinal disorders in newborn calves when applied to pregnant cows.

CHARACTERIZATION OF (Mg0.5ZN0.5)TiO3 CERAMICS AS MATERIAL CANDIDATES FOR DIELECTRIC RESONATOR AT MICROWAVE FREQUENCY

MgTiO3 ceramic is one of the dielectric materials used as a signal generator (dielectric resonator) in microwave telecommunication devices. This research is intended to explore the possibility of a new composition of MgTiO3-based ceramic, i.e. (Mg0.5Zn0.5)TiO3 (abbreviated MZT05) as a dielectric resonator material. The aim was to characterize the resonant frequency of the ceramics on the microwaves (measured using spectrum analyzer), and the results were correlated to structure (X-Ray Diffraction, XRD), microstructure (Scanning Electron Microscope, SEM), and bulk density data (Archimedes method) of the ceramics. The work was begun by compacting the MZT05 crystalline powder in a cylindrical shape with a diameter of 5 mm using a uniaxial die press to produce tablets. The tablets were sintered at 1300 ºC with variations holding times of 6, 8, and 10 h to produce ceramics. The structural data revealed that the MgTiO3 phase was identified as the main ceramics, i.e. (96.32-98.70) %molar. The bulk density increased with increasing sinter holding time, from 2.75 g/cm3 (6 h), 2.84 g/cm3 (8 h) to 2.99 g/cm3 (10 h) due to the increase in grain size diameter from 919.75 nm (6 h), 1090.62 nm (8 h) to 1180.72 nm (10 h) accompanied by a decrease in the size of the pore diameter from 924.14 nm (6 h), 917.05 nm (8 h) to 800.22 nm (10 h). The ceramics produced resonant frequencies of 5.07–5.08 GHz, which implies that the ceramics are proven to be potential candidates for dielectric resonator materials at microwave frequencies, especially at 5.07-5.08 GHz. The varying sinter holding time seems not to influence the resonant frequency of the ceramics because the variation holding times produce similar resonant frequencies.

Efficient Yellow Self-Trapped Exciton Emission in Sb3+-Doped RbCdCl3 Metal Halides.

Metal halide perovskites have flexible crystal and electronic structures and adjustable emission characteristics, which have very broad applications in the optoelectronic field. Among them, all-inorganic perovskites have attracted more attention than others in recent years because of their characteristics of large diffusion length, high luminescence efficiency, and good stability. In this work, Sb3+-doped RbCdCl3 crystalline powder was synthesized by a simple hydrothermal method, and its luminescence properties were studied, which showed a broad emission band with a large Stokes shift and efficient yellow light emission at about 596 nm at room temperature with a photoluminescence quantum yield of 91.7%. The emission came from the transition of the self-trapped exciton 1 (STE1) out of 3Pn (n = 0, 1, and 2) to S0 due to strong electron-phonon coupling, which scaled with increasing temperature. Moreover, its emission color became white at low temperatures due to the occurrence of transition of other self-trapped exciton 0 (STE0) state emission out of the 1S states of Sb ions to S0 in the lattice. These emission color changes may be used for temperature sensing, and this Sb3+-doped RbCdCl3 material expands the knowledge of the efficient luminescent inorganic material family for further applications of all-inorganic perovskites.

Atomically Dispersed Platinum in Surface and Subsurface Sites on MgO Have Contrasting Catalytic Properties for CO Oxidation.

Atomically dispersed metals on metal oxide supports are a rapidly growing class of catalysts. Developing an understanding of where and how the metals are bonded to the supports is challenging because support surfaces are heterogeneous, and most reports lack a detailed consideration of these points. Herein, we report two atomically dispersed CO oxidation catalysts having markedly different metal-support interactions: platinum in the first layer of crystalline MgO powder and platinum in the second layer of this support. Structural models have been determined on the basis of data and computations, including those determined by extended X-ray absorption fine structure and X-ray absorption near edge structure spectroscopies, infrared spectroscopy of adsorbed CO, and scanning transmission electron microscopy. The data demonstrate the transformation of surface to subsurface platinum as the temperature of sample calcination increased. Catalyst performance data demonstrate the lower activity but greater stability of the subsurface platinum than of the surface platinum.

Formation and strengthening mechanisms of xonotlite in C3S-silica and C2S-silica powder systems under high temperature and pressure

As oil and gas exploration advances into more complex underground formations, oil-well cement, used to support bore casings, is at risk of mechanical failure. To clarify the strengthening mechanisms of silica powder, the hydration characteristics of C3S-silica and C2S-silica powder systems were studied at high temperature (230 °C) and pressure (20.7 MPa). The results show that microstructural coarsening is the primary reason for the poor mechanical properties of the cementitious materials. The formation of xonotlite included two sources: the crystallisation reaction of silica powder with C-S-H and the pozzolanic reaction of silica powder with calcium hydroxide. The CaO layer in C-S-H and calcium hydroxide provided a ‘Ca’ source for the formation of xonotlite. Q2 and Q3 Si units with a high polymerisation degree improve the high-temperature stability of xonotlite, while the dense structure formed by xonotlite improves the mechanical properties. For designing high-performance high-temperature resistant cement-based materials, xonotlite should preferably be generated by selecting crystalline silica powder.

A Comparative Analysis of Structural, Optical and Electrical Properties of Polyaniline/Ferrite (Co, Ni, Cu, Zn) Composite

In this study, PANI, PANI/MFe2O4 (M = Co, Ni, Cu, and Zn) composites were studied. Polyaniline and their composites with ferrites were prepared via chemical oxidation method. Ferrites were synthesized through co-precipitation method. Structural properties were investigated using X-Ray diffraction spectroscopy (XRD) and Fourier Transform Infrared spectroscopy (FTIR) respectively. Pure ferrites were found to be of crystalline nature, whereas composites are found to be semi crystalline in nature. Scanning electron microscope (SEM) analysis confirmed the formation of all the synthesized composites. The optical band gap of composites is reducing as compared to Pure PANI (1.7 eV), which is in agreement with already reported work. The inclusions of ferrites particles have caused an enhancement in electrical conductivity of pure PANI. Conduction mechanism observed from Nyquist plots of composites is found to involve both grain as well as grain boundaries. The transition metal spinel ferrites have enhanced the optical and electric properties of PANI to a great extent, making them promising materials for different applications.