Typical Crystalline Structure Research Articles

CeαMn1-αO2 CATALYSTS SUPPORTED OVER g-Al2O3 PREPARED BY MODIFIED REDOX-COPRECIPITATION METHODS FOR n-HEXANE COMBUSTION

A series of CeαMn1-αO2 catalysts supported on γ-alumina with various molar concentrations of Ce (α, from 0 to 0.90) was synthesized by coprecipitation, applying two different precipitating agents, namely, sodium hydroxide (method 1) and sodium carbonate (method 2), with the use of sodium permanganate as a redox agent for precipitation. XRD profiles of the supported samples revealed the predominant abundance of a typical fluorite crystalline structure. TPR thermograms of supported samples were displaced towards lower temperatures with increasing Mn concentration, in contrast with the bulk samples. The supported Ce-Mn samples exhibited a greater performance in n-hexane elimination than did the corresponding simple oxides. The sample Ce0.33Mn0.67O2 obtained by method 2 presented the best activity, probably due to the enrichment of Ce4+, Mn3+ and Mn4+ surface species, an excess of superficial oxygen species and an easy reducibility as well as the lowest apparent activation energy.

Optical and structural properties of (PANI‐CSA‐PMMA)/NiNPs nanocomposites thin films for organic optical filters

ABSTRACTSynthesized nanocomposite of protonated polyaniline with camphorsulfonic acid (PANI‐CSA) hosted in poly(methyl methacrylate) (PMMA) and incorporated with nickel nanoparticles (NiNPs) were coated as thin films on activated fused silica substrates using oxygen‐plasma and spin coating techniques. Weight percent ratios of 0, 10, 20, 30, 60, and 90% of NiNPs with respect to PANI‐CSA thin films have been studied in order to investigate the optical, structural, and morphological properties of (PANI‐CSA‐PMMA)/NiNPs by employing UV–Vis spectrometer, XRD, scanning electron microscopy (SEM), contact angle (CA) goniometry, impedance analyzer, and thermogravimetric analysis. Deduced refractive indices (n) from UV–Vis data were in the range from 1.5 up to 2.2. SEM micrographs show the typical crystalline structure of PANI was vanishing gradually with increasing the NiNPs content. Optical properties such as refractive index (n), extinction coefficient (k), absorption coefficient (α) as well as the band‐gap energies (Eg) were mathematically deduced throughout the experimental transmittance and absorbance UV–Vis spectra. Calculated refractive indices (n) were in the range from 1.5 up to 2.2. Optical band‐gap energies decrease in a monoexponential decay for samples up to 60% NiNPs/PANI‐CSA, samples with 90% concentration had substantial drop in its value due to the NiNPs percolations. The incorporation with NiNPs leads to the development of a new morphological states (sheet‐like heterostructure) which start to be obvious at 30%, at this concentration the CA was maxima (54°), at this concentration and the crystallite size are maximum and the CA was maximum (highest hydrophobicity). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48643.

Analysis of morphological, thermodynamic, and mechanical properties of typical hard phase Fe–5Cr–1.5B–0.45C alloy

Fe–5Cr–1.5B–0.45C alloys exhibit excellent balance of hardness and toughness. The hard phase of boron carbide in the Fe–Cr–B–C alloy system of high-boron iron-based alloys plays a key role in various properties of the system. Therefore, in this study, several typical hard phase morphological and crystalline structures are analyzed in detail. Use of first-principle methods for calculating the thermodynamic and mechanical properties of the hard phase in Fe–5Cr–1.5B–0.45C alloys shows that the incorporation of alloying elements can further improve the properties of the alloys and the improvement of hardness can enhance the wear resistance properties.

Evaluation of Cold Resistance of Metals with Various Type of Crystal Structure

Целью настоящего исследования является оценка хладостойкости металлов с различным типом кристаллического строения, применяемых для изготовления конструкций и узлов, эксплуатирующихся в широком диапазоне низких температур.Для решения поставленной цели проведены испытания на ударный изгиб исследуемых металлов в диапазоне температур климатического холода с последующим исследованием изломов металлов.Исследования проводились с использованием методов оптической и электронной микроскопии, фрактографических исследований и рентгеноструктурного анализа. В ходе исследования получены данные по изменению ударной вязкости, механизмам разрушения металлов для широкого диапазона низких температур, а также температуре вязкохрупкого перехода и параметру кристаллической решетки исследуемых металлов.Установлено, что материалы с ГЦК- и ГПУ-решеткой проявляют бόльшую сопротивляемость разрушению при низких температурах и имеют, как правило, больший параметр кристаллической решетки по сравнению с металлами с ОЦК-решеткой. Вязкохрупкий переход в рассматриваемом диапазоне температур наблюдается только для металлов с ОЦК-решеткой. Металлы с низким содержанием углерода проявляют бόльшую сопротивляемость разрушению при ударных нагрузках, и температура вязкохрупкого перехода для таких сталей ниже.

Study on Phase Evolution and Material Properties of Li10SiP2S12-XOx

Oxygen substitution was carried out on Li10SiP2S12 (LSiPS) which has the Li10GeP2S12 (LGPS) type crystalline structure. The general formula of Li10SiP2S12-xOx (LSiPSO) where 0 ≤ x ≤ 1.75 was set for solid state reaction to produce oxy-sulfide sites. The phase distribution and local structural units of LSiPSO were determined by powder X-ray diffraction (PXRD), and Raman, FT-IR,29Si and 31P Solid State NMR spectroscopies. The LGPS like LSiPSO phase increased while the impurity phase, β-Li3PS4 was reduced and formed Li3PO4 phase by O substitution. The optimized lithium ionic conductivity was found for x = 0.7 at 3.1 x 10-3 S/cm at 25℃. However, for the higher doped oxygen such as x > 0.9, a degradation of LSiPSO occurs and it is also expected to become the Li3PO4 phase which leads to a decrease in the ionic conductivity. The local structural units was determined by 31P and 29Si NMR and spectrum deconvolution to show sulfide, oxide and mixed oxy-sulfide local units. On the other hand, the doped O was found that only incorporating with phosphate centered tetrahedral unit such as PS4-xOx during no pure orthosilicate SiO4 4- units were observed, even at the highest x examined.

Physicochemical, functional and rheological properties of fermented and non-fermented starch from canary seed (Phalaris canariensis)

This research showcases the study of physicochemical, functional and rheological changes associated to the fermentation of canary seed starch (Phalaris canariensis) in order to investigate the application of this bioproduct in food industry. The starch extraction was carried out without the use of commercial reagents and the obtained material was subjected to natural fermentation for 45 days with subsequent drying under ambient atmosphere. Microbiological analysis of the fermented starch evidenced that the microbial level was within the limits stablished in legislation and protein, lipids, moisture content, pH and acidity differed significantly from non-fermented canary seed starch. After the fermentative process, there was an increase of the amylose content of the starch, which showcased gelification at 10 % (w/v). Both fermented and non-fermented starch granules presented polygonal and irregular shape, whose diameter varied from 1.3 μm to 5.5 μm and from 0.9 to 4.4 μm, respectively. The typical crystalline structure (type A) of cereal starches was maintained after fermentation, however exhibited a strong peak of amylose-lipid complexes at diffraction angle of 2θ = 20. The fermented starch also exhibited lower viscosity and retrogradation than the non-fermented canary seed starch, and both samples showcased lower swelling power and solubility index in water than other starches reported in the literature. Furthermore, the expansion property of the fermented starch was minimal, and results suggest therefore that both non-fermented and fermented canary seed starch may have technological applications in food industry such as the production of biscuits.

ANTIBACTERIAL ACTIVITY OF ZINC OXIDE NANOPARTICLES SYNTHESIZED BY SOLOCHEMICAL PROCESS

Abstract ZnO-NPs can be obtained through various methods, resulting in nanoparticles with different size and morphology, which directly influences their antimicrobial potential. The objective of this work was to evaluate the antibacterial activity of ZnO-NPs obtained by a solochemical process against important human foodborne pathogens: Staphylococcus aureus, Salmonella Typhimurium, Bacillus cereus and Pseudomonas aeruginosa. ZnO-NPs were identified as nanorods with the length between 90.1 and 100 nm (10.5 % frequency), the diameter between 80.1 and 90 nm (21 % frequency), and wurtzite type crystalline structure. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were equal to 0.05 mg mL-1 and 0.5 mg mL-1 for S. aureus and S. Typhimurium, respectively, lower than previous results related in the literature. ZnO-NPs produced by solochemical method had a superior antibacterial activity. For instance, they can be incorporated in packaging materials for increasing microbial safety and food shelf-life by inhibiting bacterial growth.

Structures and Properties of Oxygen-Substituted Li10SiP2S12–xOx Solid-State Electrolytes

Li10SiP2S12 (LSiPS), which has an Li10GeP2S12 (LGPS)-type crystalline structure, was synthesized by solid-state reaction and then doped with oxygen to produce oxy-sulfide compositions of the genera...

Study on material properties of Sn- and Cu-doped ZnO thin films as n- and p-type thermoelectric materials based on wet solution synthesis

Sn-doped n-type and Cu-doped p-type ZnO films were fabricated by depositing solutions derrived by sol–gel route on glass substrates through dip-coating cycles. The X-ray diffractometry demonstrates the typical crystalline structure of hexagonal wurzite of ZnO. The surface morphology was made through scanning electronmicroscopy showing the density and shape of films’ grains of which size was determined between 40 and 55 µm. The results of Hall measurement indicate clearly the material nature of fabricated films at room temperature. The best electrical property of Sn-doped n-type ZnO films is corresponding to Sn content of 2 at.% with carrier concentration of 3.0 × 1018 cm−3. The formation of p-type ZnO thin films was elucidated by the manner of solution synthesis that glucose was added into the solube mixer of zinc acetate and copper(II) nitrate trihydrate and the way of thermal treatment for films in vacuum with pretty good hole concentration of about 1015 cm−3. The electrical transport properties characterizing thermoelectric (TE) behavior of all films were investigated between room temperature to 400 °C (or from 300 to 673 K). The obtained results of electrical conductivity, Seebeck coefficient and power factor revealed that Sn-doped n-type ZnO films have the quality and properties similar to Al-doped ones and Cu-doped ZnO films can be promising p-type materials for TE applications.

Structural and functional modifications of kudzu starch modified by branching enzyme

ABSTRACTKudzu starch has been used as a natural healthy food worldwide. Low solubility, poor water dispensability, high paste viscosity and low fluidity limit its wholesome utility. In order to improve its processing properties and applicability, kudzu starch has been modified using a branching enzyme (BE) from Rhodothermus obamensis and in combination with maltogenic amylase (MA) from Bacillus stearothermophilus. The results indicated that amylose content and molecular weight decreased with enzyme treatment but the proportion of short chains and branch density increased. The natural A-starch type crystalline structure changes to V-type but with decreased crystallinity. The storage modulus and loss modulus depended on the enzyme treatment time. Overall, enzymatic modification results in starch fractions with increased solubility and paste transparency, reduced gelatinization temperature, gelatinization enthalpy, and viscosity. The outcome opens up new opportunities to develop more palatable and marketable products based on kudzu starch.

Amylopectin structure and crystallinity explains variation in digestion kinetics of starches across botanic sources in an in vitro pig model

BackgroundStarch is the main source of energy in commonly used pig diets. Besides effects related to the extent of starch digestion, also several effects related to variation in digestion rate have recently been demonstrated in non-ruminants. Different rates of starch digestion in animals and in in vitro models have been reported, depending on the botanic origin of starch. Starches from different botanic sources differ widely in structural and molecular properties. Predicting the effect of starch properties on in vitro digestion kinetics based on existing literature is hampered by incomplete characterization of the starches, or by a selective choice of starches from a limited number of botanic sources. This research aimed to analyse the relationships between starch properties and in vitro digestion kinetics of pure starches isolated from a broad range of botanic origins, which are used in non-ruminant diets or have a potential to be used in the future. Therefore we studied starch digestion kinetics of potato, pea, corn, rice, barley, and wheat starches, and analysed the granule diameter, number of pores, type and amount of crystalline structure, amylose content and amylopectin side-chain length of all starches.ResultsMultivariate analysis revealed strong correlations among starch properties, leading us to conclude that effects of most starch characteristics are strongly interrelated. Across all analysed botanic sources, crystalline type and amylopectin chain length showed the strongest correlation with in vitro digestion kinetics. Increased percentages of A–type crystalline structure and amylopectin side chains of DP 6–24 both increased the rate of digestion. In addition, within, but not across, (clusters of) botanic sources, a decrease in amylose content and increase in number of pores correlated positively with digestion kinetics.ConclusionThe type of crystalline structure and amylopectin chain length distribution of starch correlate significantly with digestion kinetics of starches across botanic sources in an in vitro pig model. Variation in digestion kinetics across botanic sources is not additively explained by other starch properties measured, but appears to be confined within botanical sources.

RAMAN SPECTROSCOPY OF CaCu3Ti4O12 CERAMICS REVISITED

The CaCu3Ti4O12 ceramic has been prepared by Solid State Reaction method in excess oxygen. It possesses a well-defined double-perovskite type crystalline structure and exhibits a colossal dielectric constant at around 50000 at room temperature. This paper revised the imprints of Raman spectroscopy of this compound to validate its structural characteristics and optical behaviors. A special attention is paid on the account of optical phonons which show a recognizable agreement with the other results recently reported

Application of Fly Ash Derived Zeolites in Warm-Mix Asphalt Technology.

In recent years, numerous studies have been carried out on new technologies allowing to reduce of mix asphalt production temperatures. One of the possibilities is to foam the asphalt with “water-containing” additives, which include zeolites. So far, mainly synthetic zeolites of the Linde A structure type, obtained from chemical reagents, and natural clinoptilolite have been used in WMA technology. In this studies, the synthetic zeolites produced from fly ashes with 4 different types of crystalline structure were analyzed. Zeolite materials were characterized by textural parameters and thermal analysis. The amount of zeolite added to asphalt was 0, 3, 5, 7 wt % in relation to the weight of asphalt. Determination of dynamic viscosity was performed at two temperatures: 135 and 160 and 4 time intervals. The tests were performed for two asphalt binders: 35/50 and 100/150 penetration grade. As a conclusion, it was found that the viscosity of asphalt pastes with zeolitic materials increases with the increase in the amount of zeolite added. The increase level depends mainly on the textural parameters. The potential usefulness of fly ash derived zeolites in the process of asphalt foaming, which depends mainly on the amount of water contained in the zeolite structure and the method of its release, has been proved.

Characterization of Several Microcrystalline Cellulose (MCC)-Based Agricultural Wastes via X-Ray Diffraction Method

In this study, microcrystalline cellulose (MCC) was extracted from various types of local agricultural wastes. Four types of agricultural waste such as coconut coir, banana stem, sugarcane bagasse and pineapple leaves were collected, extracted and hydrolyzed into microcrystalline cellulose, using pre-treatment (alkaline and bleaching) and acid hydrolysis, respectively. The extracted MCC were analyzed and compared with those of commercially available MCC. The study of crystallinity behaviors of the obtained MCC was performed by X-Ray Diffraction (XRD) analysis. The XRD of MCC revealed that the crystallinity of pineapple leaves has the highest crystallinity index with 75% in value and closest compared to commercial MCC, 81.25%. The value of crystallinity index for banana stem is 74.55% followed by coconut coir, 72.73% and sugarcane bagasse, 66.50%. All of the MCC samples showed the similar pattern with the typical crystalline structure of cellulose I. The crystallite size of all MCC samples was calculated and found in the range of 4.04 – 5.14 nm. These extracted MCC that obtained from several agricultural wastes was supposed to have a high potential as value-added products in industrial applications.

Electrical properties of Y/Mg modified NiO simple oxides for negative temperature coefficient thermistors

AbstractThe semiconductors based on simple oxide have unique features with controllable electrical property by element doping. Y3+ doped NiO (Ni1−xYxO, x ≤ 0.01) and Mg2+ substituted Ni0.995Y0.005O (Ni0.995−yY0.005MgyO, y ≤ 0.5) powders were synthesized by a wet chemical method. The related ceramics were obtained by conventional ceramic processing. Phase component, microstructure, electrical property and temperature sensitivity of the prepared ceramics were investigated. All ceramics have a rock‐salt type crystalline structure. The room‐temperature resistivity of the ceramics can be widely adjusted from 254 to 12 322 Ω·cm by changing the concentrations of Y3+ and Mg2+ ions. The samples show typical characteristics of negative temperature coefficient of resistivity and have high temperature sensitivity with material constants higher than 4745 K. The analysis of impedance spectra indicates that the electrical properties resulted from both grain effect and grain boundary effect. Both band conduction and small polaron hopping were proposed as possible conduction mechanisms in the studied ceramics.

Ab-initio prediction of half-metallicity in Lithium chalcogenides compounds LiX (X=S, Se and Te) in zinc-blende and wurtzite structures

The first-principles full-potential linearized augmented plane-wave method (FPLAPW) based on density functional theory (DFT) is used to investigate electronic, structural and magnetic properties of LiX (X = S, Se and Te) binary compounds in assumed five types of crystalline structures (rocksalt (B1), CsCl (B2), ZB (B3), WZ (B4) and NiAs (B81)). Using the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA-PBE), we find that, due to the spin polarized p orbitals of group VI elements, ZB and WZ LiS and ZB LiSe are half-metallic ferromagnets with an integer magnetic moment of 1 μB per formula unit. However, by using mBJ-GGA-PBE the three compounds LiS, LiSe, and LiTe in the ZB and WZ structures are half-metallic ferromagnets with an integer magnetic moment of 1 μB per formula unit. In all the cases and for the three Li based compounds, the ferromagnetic phase is energetically favored with respect to the paramagnetic one, expect for LiS compound in NiAs structure, its paramagnetic phase is energetically favored with respect to the ferromagnetic.

Characterization of temperature induced resistivity jump in Li/Y/Cr co-doped ZnO ceramics

ZnO-based ceramics, (Zn0.9725Y0.0025Cr0.025)1−xLi x O (x = 0, 0.02, 0.05, 0.07, and 0.10), were prepared by a wet chemical route followed by a traditional ceramic sintering technology. The phase component, electrical properties, and resistivity-temperature characteristic of the prepared ceramics were investigated. The results reveal that all the prepared ceramics have a wurtzite type crystalline structure, and show an abnormal resistivity-temperature characteristic as that of the typical positive temperature coefficient (PTC) thermistors. The ZnO-based ceramics exhibit high resistivity jump with the log(ρmax/ρmin) higher than 3.13, and have a high resistivity temperature coefficient (α) of about 43–65% K−1, accompanying with the Curie temperatures changing from 313 to 386 K for various Li contents. The analysis of impedance spectra reveal that both grain effect and grain boundary effect contribute to the conduction and PTC effect of the studied ceramics.

Oxidation and ablation resistant properties of pack-siliconized Si-C protective coating for carbon/carbon composites

Uniformly SiC coating was established on carbon/carbon (C/C) composites using halide activated pack cementation (HAPC). The siliconizing temperature in HAPC process played an evident effect on the deposition efficiency and oxidation behavior of SiC coating. The SiC coating revealed a typical crystalline structure with limited porosity and combined well with the substrate. Oxidation tests showed that the coating can withstand the 25 h of continuous isothermal oxidation at 1773 K and 10 thermal cycles between 1773 K and room temperature due to the good self-healing ability of formed glassy SiO2 scale. An oxyacetylene flame test demonstrated that the SiC coating can effectively protect C/C composites from ablation for 45 s. The ablation central region presented a discontinuous and damaged morphology due to the volatilization of oxides and thermos-mechanical denudation, while a continuous glassy SiO2 layer as the primary ablation barrier availably prevented the transitional region from being heavily oxidized.

PHBV/CNC bionanocomposites processed by extrusion: Structural characterization and properties

Bionanocomposites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) with cellulose nanocrystals (CNC) were processed by extrusion. Differential scanning calorimetry (DSC) showed that with increasing the amount of CNC the overall crystallization time was reduced. Wide angle X – ray scattering (WAXS) showed diffraction peaks of orthorhombic α– type crystalline structure and confirmed the nucleating agent effect of CNC particles in the PHBV matrix. Small angle X‐ray scattering (SAXS) showed that the reducing rate of long spacing was slower in the filled sample than in PHBV. Microscopy images (Scanning Electron Microscopy, SEM, and Transmission Electron Microscopy, TEM) revealed well‐dispersed morphology in low loading of the filler while slight agglomerations appeared at higher filler concentration. Statistical analysis was done by applying a one‐way ANOVA (α = 0.05) to evaluate the effect of filler on mechanical properties of PHBV. Water vapor, oxygen and carbon dioxide transmission rate showed that the incorporation of CNC nanocrystals led to an improvement in the barrier properties of the bionanocomposites due to higher crystallinity and more tortuosity in their morphologies. POLYM. COMPOS., 40:E275–E284, 2019. © 2017 Society of Plastics Engineers

Physicochemical, morphological, thermal and pasting characteristics of starches from moth bean (Vigna aconitifolia) cultivars grown in India: an underutilized crop.

This is a first kind of study on genotype diversity of starches of Moth Bean an underutilized pulse of India. Physicochemical properties like amylose content (7.8-21.4%), swelling power (11-13.5g/g), solubility (5.9-9.0%) of starches were observed to differ significantly among the six moth bean starches. Swelling power of all the moth bean starches was observed to increase in the temperature range of 55-95°C. Scanning electron microscopy indicated polyhedral, irregular shape of granule. X-ray diffraction studies indicated a 'C' type crystalline structure and the starches differed significantly in relative crystallinity (17-34%) which affected significantly retro gradation tendencies of the starches. Peak viscosity of starches varied significantly and ranged between 4580 and 5087cP. Resistant starch content of starches also varied significantly among the cultivars and ranged between 57.3 and 75.6%.