X-ray Diffraction Peak Intensity Research Articles

Hexagonal Enhanced Porous GaN with Delayed Integrated Pulse Electrochemical (iPEC) Etching

This present study investigates the effect of time delay (Td) on the formation of porous GaN (P-GaN) using integrated pulse electrochemical (iPEC) etching. Porous GaN (P-GaN) was formed by etching an N-type GaN wafer with a 4% KOH electrolyte for 60 minutes under an ultraviolet (UV) lamp at a current density of 80 mA/cm2. A Td of 120 minutes was applied before electrochemically etching the P-GaN sample. The top view image of the field emission scanning electron microscopy (FESEM) revealed a significant difference when a Td was applied. A dense and uniform hexagonal P-GaN was obtained from the Td iPEC sample, while the non-Td sample exhibited a multi-layered hexagonal porous structure with unfinished pore-etched areas. Higher porosity and deeper pores were observed in the Td sample. Intense high-resolution X-ray diffraction (HR-XRD) peak intensity was observed in the Td iPEC sample with a lower full width half maximum (FWHM), indicating that the sample had better crystallinity. The Raman spectra of the sample anodized with a Td exhibited higher Raman peak intensity and a slight shift to a higher frequency concerning as-grown GaN, indicating better crystallinity and a tensile stress relaxation of 0.24 GPa. Post etching, a blue shift of the photoluminescence (PL) peak, from 364 nm (as-grown GaN) to 363 nm (P-GaN), was observed, and a small PL peak started to form around 385 nm compared to the as-grown GaN due to the relaxation of the tensile stress, which modified the bandgap. The PL peak intensity of the Td sample was higher than the non-Td sample, indicating that the porosity and uniformity allowed more light interaction with the material, resulting in more efficient photon absorption and emission. The results indicated that potentially efficient optoelectronics devices can be fabricated on a P-GaN using a combination of electroless and electrochemical etching of the GaN epitaxial layer.

Polyaniline/reduced graphene oxide nanocomposites for electrochemical and solar cell applications

Polyaniline nanocomposites are synthesized via in situ chemical oxidation method by reinforcing reduced graphene oxide nanoparticles of various weight percentage. Structural, optical, thermal and electrochemical studies are performed to know the significance of introducing reduced graphene oxide into polyaniline and to analyse the importance of filler weight percentage in determining various properties of the nanocomposites. X-ray diffraction peak intensity is appeared to be maximum for nanocomposite doped with 2% filler. This composite shows minimum crystallite size and maximum photoluminescence intensity. Maximum ID/IG ratio obtained for 2% filler added nanocomposite from Raman spectroscopy studies proved that the presence of more surface defects and recombination of charge carriers are the reasons for enhanced photoluminescence. Thermal stability is found to be better for a nanocomposite with 1% reduced graphene oxide and obtained a mass retention of 60% even after heating up-to 600 °C. SEM images give various shapes of nanocomposite such as nanorods, spherical nanoparticles and button shaped nanocomposites for different filler weight percentage. Carbon to oxygen ratio is observed to be decreased as the filler percentage increased from 1% to 4% in SEM-EDAX analysis. Polymer nanocomposite with 1% reinforcement possess maximum UV and visible absorption and is found to be decreased as filler concentration increased from 1 to 4%. Electrochemical analysis is performed for polyaniline and 1% reduced graphene oxide reinforced polyaniline nanocomposite. Specific capacitance of the electrode is obtained as 212 F g−1 and 609 F/g for polyaniline and nanocomposite respectively at a scan rate of 0.01 V/S. Solar cell device performance study shows that power conversion efficiency is 5.54% for 1% reduced graphene oxide nanocomposite, 4.7% for 2% reinforced, 4.16% for 3% filler and 3.61% for 4% nanocomposite.

Improving the photoelectrochemical performance of WO3 photoelectrodes by controlling the pH and Na+ ion concentration through varying the number of H2WO4 precipitate washing treatments

In this study, WO3 thin-film photoelectrodes were grown on fluorine-doped tin oxide (FTO) substrates using the spin coating method. The H2WO4 precipitate underwent various washing treatments to prepare the Na2WO4 precursor solution, which was subsequently used for growing photoelectrodes. We found that washing with the H2WO4 precipitate changed the Na + ion concentration and pH of the precursor solution containing the H2WO4 precipitate and subsequently affected the thickness, X-ray diffraction (XRD) peak intensity, optical energy bandgap, flat-band potential, and photoelectrochemical (PEC) properties of the WO3 photoelectrode. In particular, the Na + ions in the H2WO4 precipitate solution negatively affected the PEC properties by causing photogenerated electron–hole recombination and worsening the adhesion between the substrate and the WO3 thin film. Therefore, H2WO4 precipitate washing treatment is crucial for reducing the Na + ion concentration in solutions containing H2WO4 precipitate. Consequently, among the samples grown using different numbers of washing treatments, the sample grown using 12 precipitate washing treatment cycles exhibited the highest photocurrent density of 1.37 mA/cm2 and a photostability of 97.5 %. In this study, the morphological, structural, optical, electrical, and PEC properties of WO3 photoelectrodes subjected to H2WO4 precipitate washing treatment were systematically analyzed.

Potassium Iodide Doping for Vacancy Substitution and Dangling Bond Repair in InP Core-Shell Quantum Dots.

This work highlights the novel approach of incorporating potassium iodide (KI) doping during the synthesis of In0.53P0.47 core quantum dots (QDs) to significantly reduce the concentration of vacancies (i.e., In vacancies; VIn-) within the bulk of the core QD and inhibit the formation of InPOx at the core QD-Zn0.6Se0.4 shell interfaces. The photoluminescence quantum yield (PLQY) of ~97% and full width at half maximum (FWHM) of ~40 nm were achieved for In0.53P0.47/Zn0.6Se0.4/Zn0.6Se0.1S0.3/Zn0.5S0.5 core/multi-shell QDs emitting red light, which is essential for a quantum-dot organic light-emitting diode (QD-OLED) without red, green, and blue crosstalk. KI doping eliminated VIn- in the core QD bulk by forming K+-VIn- substitutes and effectively inhibited the formation of InPO4(H2O)2 at the core QD-Zn0.6Se0.4 shell interface through the passivation of phosphorus (P)-dangling bonds by P-I bonds. The elimination of vacancies in the core QD bulk was evidenced by the decreased relative intensity of non-radiative unpaired electrons, measured by electron spin resonance (ESR). Additionally, the inhibition of InPO4(H2O)2 formation at the core QD and shell interface was confirmed by the absence of the {210} X-ray diffraction (XRD) peak intensity for the core/multi-shell QDs. By finely tuning the doping concentration, the optimal level was achieved, ensuring maximum K-VIn- substitution, minimal K+ and I- interstitials, and maximum P-dangling bond passivation. This resulted in the smallest core QD diameter distribution and maximized optical properties. Consequently, the maximum PLQY (~97%) and minimum FWHM (~40 nm) were observed at 3% KI doping. Furthermore, the color gamut of a QD-OLED display using R-, G-, and B-QD functional color filters (i.e., ~131.1%@NTSC and ~98.2@Rec.2020) provided a nearly perfect color representation, where red-light-emitting KI-doped QDs were applied.

Successive ionic layer adsorption and reaction grown silver nanoflowers as an efficient flexible SERS substrate

The detection limitations of surface-enhanced Raman spectroscopy (SERS) sensors largely depend on the nano tip structure, yet the methods for constructing it are often overly complex. Here, we introduce a method using successive ionic layer adsorption and reaction (SILAR) to synthesize silver nanoflowers (AgNFs) within and on the surface of soft cellulose filter paper. This synthesis relies on a redox reaction involving silver nitrate (AgNO3) and ascorbic acid (AA), with no surfactants or additional agents utilized. Key synthesis parameters were investigated, such as the molar concentration of reactants and the number of synthesis cycles performed. As a result, the detection limit for rhodamine 6G (R6G) using SERS approached 10−11 M when deposited on the optimally synthesized AgNFs sample, yielding a corresponding enhancement factor of 8.9 × 108. The growth mechanism of AgNFs was analyzed by examining morphological changes over the initial five reaction cycles, and differences in X-ray diffraction (XRD) peak intensity ratios of (111) and (200) among the samples were considered. These findings pave a way for the development of high performance, Ag-based flexible SERS substrates.

Proximity Porosity and Crystallinity Analysis as Clay/Nickel Slag Characteristics for Material Stabilization Application

Slag nikel is a by-product of nickel ore smelting through the pyrometallurgical process, which contains silica (> 50 %). This suggests that nickel slag, possessing pozzolanic properties, which potentially to be used as a binding material in construction projects dealing with low soil bearing capacity, such as soil improvement for road foundation. Pozzolanic reactions are greatly influenced by the chemical bonds formed between the binding material and the soil, causing mechanical characteristic changes in the soil. This study aims to examine the effect of adding nickel slag to soft soil based on changes in its physical, mechanical and chemical properties. Physical and mechanical property tests were conducted according to ASTM standards, while the changes in chemical structure in the soil were analyzed based on X-Ray Diffraction (XRD) test results. In this study, nickel slag percentages of 3, 6, 9 and 12 % were used based on the weight ratio of clay soil, at optimum water content (wopt). Furthermore, the test specimens were cured for 14, 28 and 56 days to observe the effect of time on the increase of crystal phases in each variation. The results showed that the presence of nickel slag in the soil can affect its physical and mechanical properties. The nickel slag content in the soil of 3, 6, 9 and 12 % reduces the plasticity index by 16.69, 12.02, 8.86 and 6.38 %, respectively. Meanwhile, the density values increased by 10.97, 11.27, 11.68 and 12.01 kN/m3, respectively. The changes in physical and mechanical properties can be explained by the XRD analysis results, showing changes in the spectrum curve and peak intensity of X-Ray Diffraction in the soil with the addition of nickel slag. This explanation clarifies the transformation of the soil’s atomic structure from an amorphous state to a crystalline form, which is stabilized by nickel slag. HIGHLIGHTS The silica-rich nature of nickel slag offers a feasible alternative for chemical soil stabilisation The stabilization of soft soil with nickel slag results in a decrease in the plasticity index and an increase in density Immersion duration shows a changing response for the crystallinity index and porosity of the material GRAPHICAL ABSTRACT

Interfacial reaction behavior between ferromagnetic CoFeB and the topological insulator Sb2Te3

The successful prevention of interfacial reactions between ferromagnetic materials and topological insulators (TIs) is crucial for the realization of reliable spintronic devices using TIs. To this end, we investigated the magnetic properties and interfacial reaction behavior of a bilayer structure composed of ferromagnetic CoFeB and TI Sb2Te3. The effects of including a MgO interlayer was also investigated. Ferromagnetic resonance (FMR) studies showed a remarkably weak resonance peak for the sample annealed at 400 °C for the 2-nm-thick interlayer, and finally, no resonance peak for a film below 1 nm in thickness was observed. X-ray diffraction (XRD) results demonstrated that the Sb2Te3 peak intensities started to decrease upon annealing at 200 °C and completely disappeared for annealing temperatures >400 °C. Hard X-ray photoelectron spectroscopy (HAXPES) results also support that the core-level peaks of Sb and Te split upon annealing at temperatures >200 °C, suggesting the dissociation of Sb2Te3. These results indicate that Sb2Te3 and CoFeB react at the interface during annealing, resulting in a loss of the ferromagnetic properties of the CoFeB layer. Meanwhile, a sample containing a 3-nm-thick MgO layer retained its original Sb2Te3/MgO/CoFeB structure even after annealing at 400 °C, as evidenced by its unchanged XRD peak intensity and FMR spectrum. We expect that our findings will be highly valuable in developing TI-based spintronic devices.

Lattice variation as a function of concentration and grain size in MgO–NiO solid solution system

The study aimed to understand how changes in crystal's size affect the lattice parameters and crystal structure of Mg1-xNixO solid solution for six X values ranging from x = 0 to x = 1. Mg1-xNixO was synthesized via two different wet-chemical techniques: the sol-gel and the microwave hydrothermal method, both followed by calcination at different temperatures of 673, 873, 1073, 1273 and 1473 K. As annealing caused grain growth, the varied temperature range allowed to examine a wide range of grain sizes. The lattice parameters and x values were determined from XRD (X-ray diffraction) peak positions and intensities respectively. The grain size was evaluated by XRD line profile analysis and supported by SEM (scanning electron microscope) observations. At the temperatures of 673 and 873 K grain size was in the nanometric range and from 1073 K and above grain size was in the micrometric range. A non-monotonic lattice variation versus grain size was found for each concentration. When grain size decreased there was a slight contraction, however for grain size in the nanometric range there was a severe lattice expansion. Both lattice parameter changes were explained by two effects acting together: contraction due to surface stress and expansion due to weakening of the ionic bonding at nanocrystalline particles. In this current research study, the lattice parameter was mapped in two dimensions: concentration and grain size. The findings of this study provided valuable insights into the lattice variation in the MgO–NiO solid solution system.

Synthesis of strontium oxide-zinc oxide nanocomposites by Co-precipitation method and its application for degradation of malachite green dye under direct sunlight

Photocatalysts workable under direct sunlight are the safe and cost-effective option for water purification. The nanocomposites of strontium oxide and zinc oxide (SZ NCs) were synthesized using coprecipitation method. The respective precursors of SZ NCs were subjected to alkaline hydrolysis and subsequently thermally treated to yield SZ NCs. The SZ NCs with different ZnO composition was synthesized by varying the concentration of ZnO precursor from 0.2 to 1 M. The structural properties of SZ NCs evaluated using X-Ray diffraction (XRD), Thermogravimetric analysis (TGA), and Differential thermal analysis DTA). The optical properties of SZ NCs studied using ultraviolet–visible (UV–Vis) spectroscopic study. The trend observed in the intensity of XRD peaks indicated the occurrence of Zn doping in the crystalline lattice of SrO and the formation of SrO–ZnO composite. Upon incorporation of 1 M of ZnO precursor, the grain size of the SrO was decreased from 49.3 to 27.6 nm. The weight loss in the thermal analysis indicates the removal of carbonates from the sample upon heating and shows the formation of an oxide structure. UV–Vis spectra confirmed that the presence of SrO enhanced the sunlight absorption of SZ NCs. The increase in the composition of ZnO precursors increased the bandgap of SrO (2.09 eV) to the level of ZnO (3.14 eV). SZ NCs exhibited heterostructure morphology, where the nanosized domains with varying shapes (layered and rod-like) were observed. Under direct sunlight conditions, SZ NCs prepared using 1 M/0.6 M of SrO/ZnO precursors exhibited 15–20 % higher photocatalytic efficiency than neat SrO and ZnO. In precise, 1 mg of this SZ NC was degraded 98 % of malachite green dye dissolved in water (10 ppm) under direct sunlight. Additionally, the thermal stability results showed that 18 % decomposition was obtained due to the degradation impurities in SrO/ZnO catalysts and the XRD results revealed that no structural change is obtained in SrO/ZnO photocatalysts after stability test. The SZ NCs can be effectively used as safe and economic sunlight photocatalysts for water purification in remote areas without the electricity.

Uncooled mid-wavelength InAsSb/AlAsSb heterojunction photodetectors

A mid-wavelength p–B–i–n infrared photodetector constituting ternary alloys of an InAs0.9Sb0.1 absorber and an AlAs0.05Sb0.95 electron barrier was demonstrated to operate at room temperature. The results of high-resolution x-ray diffraction (XRD) analysis indicate the high crystalline quality of the barriode detector structure, grown via molecular beam epitaxy, as supported by the strong XRD peak intensity of InAsSb and its corresponding defect density as low as ∼2.0 × 108 cm−2. The dark current of the barriode detector remained diffusion-limited in the 280–300 K temperature range, and generation–recombination became dominant at 220–260 K owing to the deep-level traps in the depletion region of the absorber and near the lattice-mismatched heterointerface of AlAsSb/InAsSb. Two distinct shallow traps in the InAsSb absorber were identified through Laplace deep-level transient spectroscopy with the activation energies of Et1 = 20 meV and Et2 = 46 meV. The Et1 trap is associated with the hole localization states induced by the alloy disorder of InAsSb, whereas the Et2 trap originated from a point defect of In vacancies in InAsSb. At 300 K, the barriode detector exhibited a 90% cutoff wavelength of 5.0 μm, a peak current responsivity of 0.02 A/W, and a dark current density of 1.9 × 10−3 A/cm2 under a bias voltage of −0.3 V, providing a high specific detectivity of 8.2 × 108 cm Hz1/2/W.

Characterization of Starch Physicochemical Properties and Grain Transcriptome Reveal the Mechanism for Resistant Starch Accumulation

Understanding the physicochemical properties of starch during grain development and the mechanism for resistant starch (RS) accumulation will provide useful information for improving the RS content of wheat. The grains from wheat mutant lines with high RS contents and their corresponding wild-type control were analyzed to characterize the structural and physicochemical properties of wheat starch. A transcriptomic analysis was used to analyze the differentially expressed genes (DEGs) involved in RS accumulation. The results showed that the RS content increased with grain development, along with the total starch content, but a larger increase was observed in the middle and later stages of grain filling. The X-ray diffraction peak intensity and relative crystallinity of starch exhibited the lowest and highest values at 10 days after anthesis, respectively. Regarding the thermal properties of starch, the peak temperature and conclusion temperature generally decreased with grain development; however, the enthalpy values showed no apparent regularity. Compared to control cultivar ZM22, the RS639 and RS683 lines with high RS contents showed high amylose contents and high relative crystallinity and a large proportion of 2.0~9.8 µm starch granules. Furthermore, the transcriptomics analysis revealed that the average relative expression of the glucan-branching enzyme (GBE) α-1,4 glucan phosphorylase (Pho) and starch synthase (SS) in ZM22 was 2.47-, 2.70-, and 2.56-fold higher than that in RS639, respectively; which indicates that the downregulation of the expression of genes encoding GBE, Pho, and SS in wheat grain promotes the accumulation of RS.

Drug-Facilitated Crystallization of Spray-Dried CD-MOFs with Tunable Morphology, Porosity, And Dissolution Profile.

Metal-organic frameworks (MOFs) with versatile functionalities have applications in environmental science, sensor separation, catalysis, and drug delivery. In particular, MOFs used in drug delivery should be biodegradable and easy to control. In this study, spray-dried cyclodextrin-based MOFs (CD-MOFs) with tunable crystallinity, porosity, and dissolution properties were fabricated. The spray-drying precursor properties, such as ethanol volume ratio, incubation time, and precursor concentration, were optimized for controlled crystallization. On the basis of the morphology, X-ray diffraction peak intensity, and specific surface areas of the spray-dried CD-MOF products, they were categorized as amorphous, partially crystalline, and highly crystalline. An active pharmaceutical ingredient ketoconazole (KCZ) was introduced into the precursor to prepare KCZ-containing CD-MOFs. The surface areas of these products were greater by 3-fold (292 m2/g) than that of the plain CD-MOF (94.1 m2/g) prepared using the same parameters. The presence of KCZ in the hydrophobic cavity between the two γ-CD molecules was correlated to the CD-MOF crystal growth. Additionally, CD-MOF particles exhibited different dissolution behaviors on the basis of the position of KCZ in the MOF. These spray-dried CD-MOFs with tunable morphology, specific surface area, and dissolution could have potential applications in various fields.

Synthesis and characterization of copper oxide nanoparticles: its influence on corn (Z. mays) and wheat (Triticum aestivum) plants by inoculation of Bacillus subtilis.

Nanotechnology is now playing an emerging role in green synthesis in agriculture as nanoparticles (NPs) are used for various applications in plant growth and development. Copper is a plant micronutrient; the amount of copper oxide nanoparticles (CuONPs) in the soil determines whether it has positive or adverse effects. CuONPs can be used to grow corn and wheat plants by combining Bacillus subtilis. In this research, CuONPs were synthesized by precipitation method using different precursors such as sodium hydroxide (0.1M) and copper nitrate (Cu(NO3)2) having 0.1M concentration with a post-annealing method. The NPs were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM), and ultraviolet (UV) visible spectroscopy. Bacillus subtilis is used as a potential growth promoter for microbial inoculation due to its prototrophic nature. The JAR experiment was conducted, and the growth parameter of corn (Z. mays) and wheat (Triticum aestivum) was recorded after 5days. The lab assay evaluated the germination in JARs with and without microbial inoculation under CuONP stress at different concentrations (25 and 50mg). The present study aimed to synthesize CuONPs and systematically investigate the particle size effects of copper (II) oxide (CuONPs) (< 50nm) on Triticum aestivum and Z. mays. In our results, the XRD pattern of CuONPs at 500°C calcination temperature with monoclinic phase is observed, with XRD peak intensity slightly increasing. The XRD patterns showed that the prepared CuONPs were extremely natural, crystal-like, and nano-shaped. We used Scherrer's formula to calculate the average size of the particle, indicated as 23nm. The X-ray diffraction spectrum of synthesized materials and SEM analysis show that the particles of CuONPs were spherical in nature. The results revealed that the synthesized CuONPs combined with Bacillus subtilis used in a field study provided an excellent result, where growth parameters of Z. Mays and Triticum aestivum such as root length, shoot length, and plant biomass was improved as compared to the control group.

Hydrothermal Modification of Chabazite for the Fixation of Cesium Ions

During the accident at the Fukushima Dai-ichi Nuclear Power Plant at March 2011, radioactive cesium (137Cs), which has a long half-life of about 30 years, was released into the environment around the plant. Therefore, methods for the recovery and fixation of 137Cs are required. The CHA-type zeolite, chabazite, has high Cs+ selectivity; Cs+ ions have a diameter of approximately 0.36 nm and can thus enter into and be adsorbed by chabazite, which contains pores with diameters of 0.38 nm. However, some Cs+ ions in the large pores may be released by cation exchange in solutions with a high cation concentration. The ANA-type zeolite (ANA) has pores with 0.28 nm diameters, which are smaller than the diameter of Cs+ ions. ANA is synthesized by an alkaline hydrothermal treatment of natural zeolites such as clinoptilolite, mordenite, and chabazite. This hydrothermal modification may be useful for the fixation of Cs+. In the present study, the modification of chabazite exchanged with Cs+ to produce ANA by hydrothermal treatment was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), and the solution stability of Cs+ in the ANA was also evaluated using inductively coupled plasma-mass spectrometry (ICP-MS). Modification of chabazite exchanged with Cs+ to produce single-phase ANA was confirmed in a 1.0 mol/L NaOH solution held at 200 °C for 3 to 144 h. The intensity of XRD peaks corresponding to (211) and (220) planes decreased with increasing Cs+ concentration. SEM observations showed that the ANA crystals had a trapezohedral shape and a size of about 5 µm. EDX analysis of ANA crystals confirmed the presence of Cs+. The amount of Cs+ eluted from ANA in a 0.6 mol/L NaCl solution was less than 1.7%.

Enhancing Resistant Starch Content of High Amylose Rice Starch through Heat-Moisture Treatment for Industrial Application.

The objective of the present study is to enhance the resistant starch (RS) content of high amylose rice starch with heat–moisture treatment (HMT) for industrial application. The optimized HMT condition for achieving the highest RS content established using response surface methodology (RSM) was a temperature of 100 °C, moisture content of 24.2%, and a time of 11.5 h. Upon HMT, the RS content increased from 32.1% for native starch to 46.4% in HMT starch with optimized condition. HMT of the starches reduced the solubility and swelling power. The surface of HMT starch granules was more irregular than native starch. The X-ray diffraction (XRD) peak intensity at 2θ = 5° was greatly reduced by HMT, and the peaks at 22.7° and 24.2° were merged. HMT increased the gelatinization temperature and reduced the gelatinization enthalpy. HMT provides a method for the production of high-yield RS2 with high amylose rice starch in industrial application.

The Effects of Hydrochloric Acid Pretreatment on Different Types of Clay Minerals

Clay minerals are common in geological samples and are useful paleoclimate and sediment provenance proxies. Acid pretreatment is the most common method for the separation and purification of clay minerals. Given that hydrochloric acid (HCl) can dissolve chlorite and distinguish it from kaolinite, the HCl digestion method is used to simplify the routine method of clay mineral analysis. However, there have been few studies of the effects of acid digestion on different clay minerals in the context of extracting paleoclimate indicators. In this study, we used illite, chlorite, kaolinite, and two types of smectite to assess the effects of pretreatment with different HCl concentrations at variable temperatures. Our results show that chlorite is the most soluble clay mineral in HCl and can be effectively dissolved in HCl with concentrations of &gt;1 N. The variable crystal structure of smectite affects its solubility in HCl. Ca-rich smectite, which has more cation substitution of octahedral Al, can be dissolved with HCl. However, Na-rich smectite, which has less cation substitution for octahedral Al, is hardly dissolved in HCl of any concentration or at any temperature. Illite can be partly dissolved in HCl, and the threshold beyond which dissolution occurs is 5 N HCl at 70 °C. Kaolinite is relatively difficult to dissolve in HCl. Given that the HCl digestion method uses the peak intensity of the bulk sample X-ray diffraction (XRD) analysis, whereas the routine method uses the peak area of clay particles, we compared the results of clay mineral quantification and the paleoclimate proxy obtained using the two methods for synthetically prepared mixed and natural clay samples. The results obtained with the HCl digestion method are less accurate than those obtained with the routine method because of the dissolution of illite and smectite in HCl. Therefore, the HCl pretreatment method is not suitable for clay mineral analysis in paleoclimate studies. The present results provide reference data for future studies that employ the acid dissolution pretreatment of clay mineral samples to acquire and quantify paleoclimate proxies.

Phase Transition between Crystalline Variants of Ordinary Ice.

Water is one of the most abundant molecules on Earth. However, this common and "simple" material has more than 18 different phases, which poses a great challenge to theoretically study the nature of water and ice. We designed two reaction coordinates that can distinguish between water and various ice states and used them to efficiently sample all possible states of the system in all-atom molecular dynamics simulation at ambient temperature and pressure. Various structural and thermodynamics properties, including the water-ice phase diagrams, can thus be calculated. We also present a simple model that successfully explains the thermodynamic stability of different ice states. Our work provides effective methods and data for theoretical studies of different phases of water and ice.

Effects of Energetic Carbon-Cluster Ion Irradiation on Lattice Structures of EuBa2Cu3O7−x Oxide Superconductor

C-axis-oriented EuBa2Cu3O7−x oxide films that were 100 nm thick were irradiated with 0.5 MeV C monoatomic ions, 2 MeV C4 cluster ions and 4 MeV C8 cluster ions at room temperature. Before and after the irradiation, X-ray diffraction (XRD) measurement was performed using Cu-Ka X-ray. The c-axis lattice constant increased almost linearly as a function of numbers of irradiating carbon ions, but it rarely depended on the cluster size. Cluster size effects were observed in the XRD peak intensity and the XRD peak width. With increasing the cluster size, the decrease in peak intensity becomes more remarkable and the peak width increases. The experimental result implies that the cluster ions with a larger size provide a more localized energy deposition in a sample, and cause larger and more inhomogeneous lattice disordering. As such, local and large lattice disordering acts as a pinning center for quantum vortex; energetic carbon-cluster ion irradiation will be effective for the increment in the critical current of EuBa2Cu3O7−x superconductors.

Solution combustion synthesis of FeCr 2 O 4 powders for pigment applications: Effect of fuel type

Solution combustion synthesis of iron chromite was reported using iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate as starting materials, as well as glycine, urea, citric acid, and ethylene glycol as fuels. The influence of fuel type on the structure, molecular, microstructure as well as chromatic properties of samples was investigated. The X-ray diffraction (XRD) patterns showed that unlike themodynamical prediction, glycine fuel led to strongest combustion and consequent highest XRD peak intensities and lower lattice parameters. Moreover, the change of fuel type and mixing of fuels affected XRD data. Fourier transform infrared analysis showed that the band position of Cr–O and Fe–O bonds were shifted to higher frequencies by using of fuels with weaker combustion reactions. In addition, scanning electron micrographs showed that different morphologies of FeCr2O4 particles were obtained depending on the fuel type and ratios. Energy-dispersive X-ray spectroscopy analysis of the samples showed that oxygen concentration of samples was less than that of stoichiometric ratio of FeCr2O4 due to local reducing atmosphere. Furthermore, chromatic properties of the powders showed that the pigment synthesized with glycine fuel has a better and lighter grayish brown color than the other ones and can be used as a suitable industrial candidate to create a brown color in the ceramic glaze.

Formation efficiency of soil organic matter from plant litter is governed by clay mineral type more than plant litter quality

Plant litters incorporated in soils are decomposed by microorganisms and partially transformed into soil organic matter (SOM) through mineral-organic association and physical protection in soil aggregates. Few studies have linked the effects of clay mineralogy and plant litter quality on controlling the formation efficiency of SOM. Using model soils, the objectives of this study were (1) to determine the effects of clay mineral type and plant litter quality on soil respiration dynamics, and formation efficiency of SOM, physical fractions, and chemical and microbial compositions of SOM at the end of a 120-day incubation; (2) to unravel SOM protection mechanisms and extents by specific clay minerals; and (3) to understand the key role of clay minerals relative to plant litter quality in controlling SOM formation. The changes in X-ray diffraction peak intensity (in terms of peak height) of the clay minerals during incubation and after H2O2 treatment provided evidence for surface adsorption by vermiculite and pore entrapment by kaolinite and illite assemblages. The SOM protection extent parameter, defined based on accumulative soil respiration dynamics, explained well the variation of the formation efficiency of mineral associated SOM (MAOM) and, to a lesser extent, that of occluded particulate SOM (oPOM) in aggregates. 90–96% of plant litter-derived C was protected in the vermiculite material and 33–60% in the pure kaolinite and illite materials. The pure vermiculite material showed the greatest fractions of MAOM and oPOM, the highest relative abundances of O–alkyls and anomeric from carbohydrates in the MAOM fraction. < 1% of plant litter-derived C was transformed into microbial biomass and residues, and fungal residues only were associated with the pure vermiculite material. These results suggested that plant litter incorporated into the soil was decomposed mainly through the ex vivo modification pathway and transformed into SOM through both mineral-organic association and physical protection pathways. Plant litter-derived C was likely protected through mineral-organic association from the earlier stages of decomposition by vermiculite than kaolinite and illite, resulting in more plant carbohydrates associated with vermiculite. Therefore, clay minerals determined SOM formation pathways and played a greater role in controlling SOM formation efficiency than plant litter quality.