Analytical Techniques Including X-ray Diffraction Research Articles

An Innovative Approach to Manganese-Substituted Hydroxyapatite Coating on Zinc Oxide⁻Coated 316L SS for Implant Application.

In this paper, the synthesis of porous manganese substituted hydroxyapatite (Mn-HAp) coating on zinc oxide (ZnO) coated stainless steel (316L SS) using the electrodeposition technique is reported. The structural, functional, morphological, and elemental analyses are characterized by various analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results of electrochemical techniques such as cyclic polarization and impedance show that the Mn-HAp coating on ZnO coated 316L SS has the highest corrosion resistance in simulated body fluid (SBF) solution. Moreover, dissolution of metal ions was extremely reduced, as evaluated by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The adhesion and hardness of Mn-HAp/ZnO bilayer coatings have superior mechanical properties over individual coatings. Further, the biocompatibility of in vitro osteoblast attachment, cell viability, and live/dead assessment also confirmed the suitability of Mn-HAp/ZnO bilayer coating on 316L SS for orthopedic applications.

Mechanical properties, microstructural and thermal evolution of Mg65Ni20Y15−xSix (X = 1, 2, 3) alloys by mechanical alloying

We report on a work of the influence of the mechanical alloying on the microstructure, thermal and mechanical features of Mg65Ni20Y15−xSix (X = 1, 2, 3) alloys. The Mg-based alloys were produced by mechanical alloying technique from mixtures of pure crystalline Mg, Ni, Y and Si powders. These alloys were investigated using a variety of analytical techniques including x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDX) and differential scanning calorimetry (DSC). The mechanical properties of the alloys were investigated by Vickers microhardness (HV) tester. After 75 h of milling time, three different intermetallic phases were obtained. These phases were defined as Mg24Y5, Mg2Ni3Si and Mg2Ni by XRD data. The particle and crystallite sizes of the Mg-based alloys were decreased by increasing milling time and they were calculated 2 μm and ∼9 nm, respectively. From the EDX analysis, it was determined that compositional homogeneity of the Mg-based alloys was fairly high. The microhardness values of the Mg65Ni20Y15−xSix (X = 1, 2, 3) alloys increased by increasing Si into the alloys and were determined 101, 131 and 158 HV, respectively.

Use of recycled aggregates as internal curing agent for alkali-activated slag system

This study aims to investigate the feasibility of recycled aggregates (RA) as an internal curing agent for an alkali activated slag (AAS) system. The physical and chemical characteristics of the aggregates were studied through various analytical techniques including X-ray diffraction, thermogravimetry, mercury intrusion porosimetry, and indirect alkalinity measurements. The compressive strength, degree of hydration, and autogenous and dry shrinkages of AAS generated with RA were measured and compared with those of AAS made using artificial lightweight aggregates. The use of RA can reduce the autogenous shrinkage of an AAS system without a decrease in compressive strength. The degree of hydration for AAS mortar was not increased by the addition of RA owing to the dilution effect of the alkali activator, which was caused by the additional water supplied from internal curing materials.

Combustion kinetics and structural features of bituminous coal before and after modification process

Coal modification process is becoming popular to be used to upgrade coal quality. The upgraded coal (semi-coke) can be utilized in ironmaking process. Thermogravimetry and DAEM were used to analyze the combustion kinetics of bituminous coal before and after modification in this study. To understand the factors influencing the combustion process, various advanced techniques including X-ray diffraction analysis, Raman spectroscopy and Fourier transform infrared spectroscopy were adopted to investigate the structural features of the combusted samples. The results showed that the coal aromaticity increases significantly with the side-chains and chain length reduced, while the matrix structure transforms to graphite-like structure after the modification process. Those structural changes lead to the decrease in coal reactivity, thus weakening the coal combustion performance.

Iron-substituted cubic silsesquioxane pillared clays: Synthesis, characterization and acid catalytic activity

Novel pillared structures were developed from the intercalation of iron-substituted cubic silsesquioxanes in a sodium and an acid-activated montmorillonite nanoclay and evaluated as acid catalysts. Octameric cubic oligosiloxanes were formed upon controlled hydrolytic polycondensation of the corresponding monomer (a diamino-alkoxysilane) and reacted with iron cations to form complexes that were intercalated within the layered nanoclay matrices. Upon calcination iron oxide nanoparticles are formed which are located on the silica cubes (pillars) and on the surfaces of the clay platelets. Acid activation of the nanoclay was performed in order to increase the number of acid active sites in the pristine clay and thus increase its catalytic activity. A plethora of analytical techniques including X-ray diffraction, thermal analyses, Fourier transform infrared, electron paramagnetic resonance, Raman, Mössbauer and X-ray photoelectron spectroscopies and porosimetry measurements were used in order to follow the synthesis steps and to fully characterize the final catalysts. The resulting pillared clays exhibit a high specific area and show significant acid catalytic activity that was verified using the catalytic dehydration of isopropanol asa probe reaction.

Synthesis, Characterization, and Photocatalytic Behavior of Praseodymium Carbonate and Oxide Nanoparticles Obtained by Optimized Precipitation and Thermal Decomposition

Direct precipitation of insoluble praseodymium carbonate salt by reaction of the corresponding cation and anion was utilized in this study. This facile, routine, and effective route was optimized statistically through an orthogonal array design for fabrication of nanoparticles, using a Taguchi method to quantitatively evaluate the effects of the major operation conditions on the particle diameter via analysis of variance. The results indicated that high-purity particles with very small dimension (30 nm) could be produced simply by regulating the cation and anion concentrations and flow rate of introducing the cation into the anion solution. The product was thermally decomposed to yield praseodymium oxide nanoparticles by single-stage reaction. Both products were characterized using various conventional techniques including x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy to monitor the effects of the optimization on their physicochemical properties. Furthermore, the photocatalytic behavior of the nanoparticles was evaluated for treatment of water polluted with methyl orange, revealing high efficiency for degradation of the organic pollutant.

Effect of graphene oxide loading in GO/SiO<SUB align="right">2/Ag/AgCl photocatalyst

In the presented work, Ag/AgCl decorated silica nanoparticles were introduced over graphene oxide (GO) sheets to prepare GO/SiO2/Ag/AgCl nanocomposite powders for absorption and photocatalytic application. Nanocomposite powders were synthesised by sol-gel method and then characterised by various analytical techniques including X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The amount of GO in nanocomposites was varied from 1 wt.% to 50 wt.% to investigate the role of graphene oxide on the absorption and photocatalytic properties of the nanocomposites. The photocatalytic activity of the GO/SiO2/Ag/AgCl nanocomposites was examined under UV light taking methylene blue (MB) as a model dye.

Impact of surface coating on morphological, optical and photoluminescence properties of YF3:Tb3+ nanoparticles

A simple polyol and sol–gel Stober process were employed for synthesis of YF3:Tb+ (core), YF3:Tb+@LaF3 (core/shell) and YF3:Tb+@LaF3@SiO2 (core/shell/SiO2) nanoparticles (NPs). The phase purity, crystalinity, morphology, optical and photoluminescence properties were investigated and discussed with the help of various analytical techniques including X-ray diffraction pattern, FE-transmission electron microscopy (TEM), FTIR, UV/vis absorption, energy band gap and emission spectra. XRD and FE-TEM studies indicate the formation of core/shell nanostructure and ∼10nm thick amorphous silica surface coating surrounding the core-NPs, which is also confirmed by FTIR spectral results. The surface modifications of core-NPs significantly affect the optical features in the form of energy band gap, which were correlated with particle size of the nanomaterials. The comparative emission spectral results show that after inert layer coating the luminescent core-NPs display stronger emission intensity in respect to core and silica coated core/shell/SiO2-NPs. The solubility character along with colloidal stability was improved after silica surface modification, whereas luminescent intensity was suppressed causing the surface functionalized with high energy silanol (Si-OH) molecules. These novel luminescent nanomaterials with enhanced emission intensity and excellent solubility in aqueous solvents would be potentially useful for fluorescence bioimaging/optical bio-probe etc.

Structural, optical and magnetic properties of (Ni–Mn) co-doped tin oxide nanoparticles

Nickel and manganese (Ni–Mn) co-doped with tin oxide (Sn(2–(x + y)) NixMnyO2) nanoparticles were synthesised by a sol-gel method. The influence of dopant concentration on prepared samples is investigated by different analytical techniques including X-ray diffraction (XRD), vibrating sample magnetometer, diffuse reflectance spectra, scanning electron microscope (SEM) and transmission electron microscope (TEM) to study the structural, optical and magnetic properties. The XRD study reveals that the formation of single-phase rutile tetragonal structure of all the samples and also the particle size vary from 8 to 6.5nm. The lattice constant and crystallite size are decreased as the (Ni–Mn) codoped with SnO2 and found to decrease with increasing doping concentrations. Magnetic measurements show that the (Ni–Mn)-doped SnO2 exhibit room temperature ferromagnetism. SEM and TEM are used to study the external morphology and particle size of the prepared sample.

Study of the photocatalytic and antibacterial activity of tio2 powder synthesized by microwave-assisted sol-gel method

TiO2 powder was prepared by microwave-assisted sol-gel method. The powder was refluxed at 180 W for 1, 2 and 3 h and dried at 180 W for 1 h by a conventional microwave oven. Several analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area measurement (BET) were employed to characterize the synthesized powder. Photocatalytic activity of the powder was examined via the degradation of methylene blue (MB) solution under UV irradiation for a certain time. The efficiency of antibacterial activity was evaluated by the inactivation of Staphylococcus aureus (S. aureus). The results showed that only anatase TiO2 was observed and the as-prepared powder exhibited the agglomeration of spherical nanoparticles with crystallite sizes of 20.7, 13.8 and 9.3 nm when the refluxed time was 1, 2 and 3 h, respectively. The highest efficiency for the photocatalytic and antibacterial activities was 66.68 and 91.67%, respectively, belonging to those powders using the reflux time of 3 h.

Synthesis of Magnesium Oxide Nanopowder by Thermal Plasma Using Magnesium Nitrate Hexahydrate

Magnesium oxide (MgO) nanopowder was synthesized by thermal plasma in a novel thermal DC plasma torch using magnesium nitrate hexahydrate. Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O) was obtained from serpentinite (Mg3Si2O5(OH)4; lizardite) (Halilovskiy array, Orenburg region, Russia). The synthesized samples were characterized by analytical techniques including X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM characterization studies confirmed that MgO nanopowder obtained has periclase structure with high purity, and the particle sizes vary within the range of 100 nm to 150 nm. We believe that the present work will promote further experimental studies on the physical properties and the applications of MgO nanopowders in the fields such as high-densed ceramics, additives in bactericide, and refractory products.

Efficient preparation of Zr(IV)-salen grafted mesoporous MCM-41 catalyst for chemoselective oxidation of sulfides to sulfoxides and Knoevenagel condensation reactions

Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCl2·8H2O was reacted with the Schiff base ligands for complex formation. The structural properties of the synthesized materials were investigated by a number of analytical techniques including X-ray diffraction, N2 sorption-desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscpopy, and energy dispersive X-ray spectroscopy. Catalytic studies of the mesoporous materials functionalized with Zr(IV)-Schiff base complexes were investigated and extended to selective oxidation of sulfides to sulfoxides and the Knoevenagel condensation reactions of aldehydes with malononitriles and ethyl cyanoacetate. Additionally, catalyst recycling of the Zr-salen-MCM-41 materials was also studied.

Ru/CeO<sub>2</sub> 촉매를 이용한 메탄 건식 개질

Ru catalysts supported on <TEX>$CeO_2$</TEX> were synthesized by an impregnation method and characterized by numerous analytical techniques including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). Upon utilization of these catalysts for methane dry reforming with a <TEX>$CH_4/CO_2$</TEX> ratio of 1:1 at different temperatures ranging from 550 to <TEX>$750^{\circ}C$</TEX>, the <TEX>$Ru/CeO_2$</TEX> catalysts have shown to be active. In particular, Ru(0.55wt%) supported on <TEX>$CeO_2$</TEX> (1) prepared by a hydrothermal method exhibited excellent activity with the conversion of > 75% at <TEX>$750^{\circ}C$</TEX>. In addition, the catalyst also proved to be highly stable for at least 47 h without catalyst deactivation under the dry reforming conditions.

Kaempulchraols A-H, Diterpenoids from the Rhizomes of Kaempferia pulchra Collected in Myanmar.

Eight new diterpenoids, kaempulchraols A-H (1-8), along with five known analogues were isolated from the CHCl3-soluble extract of rhizomes of Kaempferia pulchra of Myanmar. The structures of these compounds were elucidated using extensive spectroscopic techniques including X-ray diffraction analysis. All the isolates were tested for their antiproliferative activity against a panel of five human cancer cell lines (A549, human lung cancer; HeLa, human cervix cancer; PANC-1 and PSN-1, human pancreatic cancer; MDA-MB-231, human breast cancer) and TIG-3, normal human primary fibroblast cells. Kaempulchraol F (6) exhibited weak activity against the human pancreatic PSN-1 cell line with an IC50 value of 12.3 μM.

Synthesis of mesoporous silica-zirconia supported phosphotungstic acid and its catalytic performance for oxidative desulfurization of fuel

Mesoporous silica-zirconia supported phosphotungstic acid was synthesized by evaporation induced self-assembly method and used as oxidative desulfurization catalysts. The structural properties of as-prepared catalysts were characterized using various analytical techniques including X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption desorption. The experimental results showed that HPW was highly dispersed on mesoporous framework. The surface acidity of catalysts was analyzed by FTIR measurement of adsorbed pyridine.The surface Lewis acidity was improved with increasing the content of zirconium in the samples. The mesoporous composites were used as catalysts with H2O2 as oxidant for oxidative desulfurization of model fuel. The catalytic activity results showed that the surface Lewis acid sites acted as selective adsorption active sites for dibenzothiophene, which facilitated the sulfur removal from model fuel in the presence of arene. A slight decrease in activity of the recovered catalyst used in the proceeding rounds indicated the reusability of the catalyst.

Photochemical synthesis, characterization and enhanced visible light induced photocatalysis of Ag modified TiO2 nanocatalyst.

Nanocomposite of titania (TiO2) and silver (Ag) has been synthesized by a photochemical deposition method. We investigated the simultaneous enhancement of visible light sensitivity and photocatalytic activities of as-prepared Ag-TiO2 nanocomposite photocatalyst. The resulting Ag-TiO2 nanomaterials were characterized by various analytical techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). Photocatalytic activity was evaluated by decomposition of methylene blue (MB) dye solution under simulated visible light irradiation. Ag nanoparticles were well dispersed on the surface of TiO2 and composite nanoparticles were effectively enhanced in visible light-induced photocatalytic activity compared to that of Ag free TiO2. It was found that the enhanced activity is result from simultaneous effects of nano-Ag deposits by increasing the absorption capacity in visible region and by acting as electron trappers to promote charge separation of photoinduced electrons (e-) and holes (h+). The effect of the amount of Ag nanoparticles on its photoactivity under simulated visible light was also investigated.

Enhanced electromagnetic wave absorption performances of Co3O4 nanocube/reduced graphene oxide composite

The Co3O4 nanocube/reduced graphene oxide (Co3O4/RGO) composite paper has been firstly fabricated via a simple process. Several analytical techniques including X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been employed to characterize the Co3O4/RGO composite. The results indicated that the Co3O4 nanocubes attached to the RGO sheets, and that the average edge length of Co3O4 nanocubes is about 200nm. The obtained composite exhibited a maximum reflection loss of −32.3dB at 12.4GHz with a coating layer thickness of 2.5mm, and the effective absorption bandwidth with reflection loss less than −10dB is up to 10.5GHz (from 5.5 to 16.0GHz) when an appropriate absorber thickness between 2 and 5mm is chosen. Such high microwave absorption composite can be used as promising candidate for the new type of electromagnetic wave absorptive material.

Solvent exchange in sulfoaluminate phases. Part II: monosulfate

The influence of organic solvent exchange techniques on the microstructure and the dimensional stability of monosulfate (3CaO.Al2O3.CaSO4.12H2O) was critically investigated. Monosulfate samples were treated with methanol, ethanol and isopropanol, and examined by different analytical techniques including X-ray diffraction, Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electrom microscopy. Nitrogen surface area measurements (Brunauer–Emmett–Teller (BET) method) and length-change of the monosulfate samples in the solvents were also recorded. Evidence was obtained that indicates monosulfate was readily dehydrated from 12 water molecules to ten water molecules once it was treated by the investigated alcohols. The alcohol molecules, however, likely intercalated into the monosulfate structure, limiting an expected decrease in the interlayer distance of the monosulfate structure. Methanol had the greatest damaging effect on the monosulfate microstructure. Ethanol, however, resulted in higher long-term expansion owing to its intermediate molecular size and reactivity with monosulfate compared to methanol and isopropanol.

Influence of the operation conditions on CO2 capture by CaO-derived sorbents prepared from synthetic CaCO3

In this work, a statistical experimental design is performed in order to prepare CaCO3 materials for use as CaO-based CO2 sorbent precursors. The influence of different operational parameters such as synthesis temperature (ST), stirring rate (SR) and surfactant percent (SP) on CO2 capture is studied by applying Response Surface Methodology (RSM). The samples were characterized using different analytical techniques including X-ray diffraction, N2 adsorption isotherm analysis and Scanning Electron Microscopy–X-ray Energy Dispersive Spectroscopy (SEM-EDX). CO2 capture capacity was determined by means of a thermogravimetric analyzer which recorded the mass uptake of the samples when these were exposed to a gas stream containing diluted (15%) CO2. The statistical approach used in this work provides a rapid way of predicting and optimizing the main preparation variables of CaO-derived sorbents for CO2 sorption. The results obtained clearly indicate that four parameters statistically influence CO2 uptake: SR, the square of SR, its interaction with SP and the square of SP.

A novel non-enzymatic glucose sensor based on NiO hollow spheres

A novel non-enzymatic glucose sensor has been constructed by using NiO hollow spheres (NiO-HSs) as sensing materials, which were prepared by a glycerin-assisted hydrothermal synthesis method. The analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicate the successful formation of NiO-HSs, assembled by NiO nanoflakes with the length of about 500nm and the width of about 50nm. It was found that the resulting NiO-HSs exhibit good catalytic activity toward the oxidation of glucose in 0.1M NaOH, leading to a non-enzymatic glucose sensor with a fast amperometric response time of less than 3s, and the detection limit is estimated to be 0.3 μM at a signal-to-noise ratio of 3. Furthermore, this sensor shows good response to glucose in comparison to other normally co-existing electroactive species (such as dopamine, ascorbic acid and uric acid).