Changes In X-ray Diffraction Patterns Research Articles

Amorphous-crystalline phase transition and intrinsic magnetic property of nickel organic framework for easy immobilization and recycling of β-Galactosidase

This work describes the synthesis of fibrous nickel-based metal organic framework (Ni-ZIF) via simple solvothermal method. The material formed was calcinated at 400, 600, 800 °C to improve its surface area, porosity and enzyme binding capacity. Changes in X-ray diffraction pattern after calcination revealed the Ni-ZIF transitioned from amorphous to crystalline structure. The surface area, pore volume and pore size for Ni-ZIF@600 were found to be 312.15 m2/g, 0.88 cm3/g and 10.28 nm, with an enzyme loading capacity of 593.85 mg/g after 30 h The free (β-Gal-LEH) and immobilized β-Galactosidase were stable at pH 7.5, temperature 50 °C, and yielded 70.70 and 63.95 mM glucose after milk lactose hydrolysis, respectively. The Ni-ZIF@600@β-Gal-LEH exhibited high enzyme retention capacity, maintaining 59.44 % of its original activity after 6-cycles. The enhanced magnetic property, enzyme binding capacity and easy recoverability of the calcinated Ni-ZIF could guarantee its industrial significance as immobilization module for enzyme-mediated catalysis.

In Situ Synchrotron X-ray Scattering Investigation of Cathodic ZIF-8 Deposition on Graphite Using 3D-Printed Cells

Electrochemical approaches provide unique means to fabricate thin films of metal-organic frameworks (MOFs). However, the kinetics of electrochemical MOF deposition has not been quantitatively investigated so far. In this study, we report the first in situ measurements of electrochemical MOF growth using transmission synchrotron X-ray scattering. Electrochemical cells based on poly(lactic acid) with two windows were fabricated using fused-deposition modeling. The resulting three-dimensional (3D)-printed cells, the surface of which was coated with paraffin wax to prevent solvent percolation through the polymer material, were used to monitor the cathodic growth of zeolitic imidazolate framework-8 (ZIF-8) on graphite in a methanol solution containing ZnCl2 and 2-methylimidazole (Hmim) at different cathodic potentials. The resulting time-resolved X-ray diffraction data showed a gradual increase in crystal size with negligible changes in crystal orientation during the cathodic ZIF-8 deposition. More importantly, the time-resolved data provided a means to quantitatively assess the kinetics of the cathodic ZIF-8 growth using the Gualtieri model, revealing that the cathodic potential and Hmim concentration affected crystal growth kinetics but not nucleation kinetics. These ZIF-8 samples exhibited changes in X-ray diffraction patterns after being washed with methanol and dried in air, indicating that in situ measurements are essential to investigate mechanisms behind MOF electrodeposition.

Preparation and characterization of fluorine-substituted LiFeBO3 with carbon coating to enhance electrochemical performance and stability as a cathode material for Li-ion batteries

The fluorine-substituted LiFeBO3 with carbon coating (LFeBF/C) has been successfully demonstrated via a solid-state reaction to enhance its electrochemical properties and stability in air. Transmission electron microscopy characterization reveals that the primary LFeBF particles are fully covered by a thin layer of amorphous carbon. The formation of vonsenite-type LFeBF/C and the distribution of Li ions into its octahedral sites due to the fluorine substitution are confirmed using X-ray diffraction and solid-state nuclear magnetic resonance measurements, respectively. The stability of the LFeBF/C in air is promoted by the carbon layer. After two months of open-air storage, no significant changes in X-ray diffraction patterns can be observed. The synergistic effects of fluorine substitution and carbon coating enhance the overall electrochemical performance of the LFeBF/C as achieving a superior initial discharge capacity of 367.0 mAh g−1 at the rate of 0.05C and 231.7 mAh g−1 at 1.0C. In addition, the cyclic stability of the LFeBF/C is improved, reaching 197.5 mAh g−1 at the rate of 1.0C after 50 cycles, which corresponds to a retention of 85% of its initial capacity.

KFeO2 with corner-shared FeO4 frameworks as a new type of cathode material in potassium-ion batteries

KFeO2 is presented as a new type of cathode material for potassium-ion batteries. In contrast to LiFeO2 and NaFeO2, KFeO2 has tetrahedrally coordinated Fe3+ ions linked by three-dimensional corner-sharing. When chemically oxidized, KFeO2 releases ca. 0.3 K+ (K0.7FeO2) and shows no apparent changes in X-ray diffraction patterns. Rietveld refinement of KFeO2 and K0.7FeO2 reveals negligible variation in the unit cell dimension and in the basic structure, but noticeable differences in FeO4 volumes and inter-tetrahedra angles due to the Jahn-Teller active Fe4+ (eg2t2g2) in K0.7FeO2. The refinement also shows no preferential extraction of K+ from two possible sites (K1 and K2), which coincides with the results from density-functional-theory calculation. In accordance with the compositional and structural analysis, KFeO2 delivers a reversible capacity of 60 mAh g−1 (ca. 0.28 K+) during the initial charge/discharge (C/D), showing a plateau-like voltage response at 3.43 V vs. K/K+. In-operando diffraction studies also show no distinctive signs of pattern evolution, which is likely due to the structural similarities of KFeO2 and K0.7FeO2. With repeated cycling, however, the reversible capacity of KFeO2 continuously decreases and falls to 30 mAh g−1 after 50 C/D cycles. The repeated changes in the FeO4 tetrahedra geometry appear to cause a decrease in the crystallinity of KFeO2, which eventually aggravates the facile K+ transport. The results of this study show that the practicality of KFeO2 can be realized via improvements of cyclability by mitigating the Jahn-Teller effect (for example, isovalent doping with Al3+or Ga3+).

Crystal structure of cellulose-iodine complex

Different from starch and amylose [(1 → 4)-α-D-glucopyranan], cellulose [(1 → 4)-β-D-glucopyranan] or wood fiber (natural cellulose or cellulose I) and paper (re-generated cellulose or cellulose II) have been believed for long years in many papers and high-school textbooks that they do not form an iodine complex at all. This legend originated from the characteristic conformation of cellulose chain, which is fully extended and had been believed to be impossible to entrap the long iodine ions likely the case of amylose helical chain. However, people often observe such a phenomenon that a filter paper is dyed easily when it is immersed into the iodine aqueous solution. On the basis of the X-ray diffraction measurements of the various kinds of cellulose materials (a piece of wood, bacteria cellulose, paper, cellophane, and so on), the present study has confirmed that cellulose forms the crystalline complex with iodine, as known from the change of X-ray diffraction pattern before and after the complexation. The crystal structure of cellulose-iodine complex has been proposed through the X-ray data analysis and the complex formation mechanism was discussed quantum-chemically by comparing the crystal structure between the original cellulose and its iodine complex. After the completion of the structural analysis of this complex, we happened to notice the paper by Hess et al. (Kolloid Z. (153) 1956, 128) reported about 60 years ago, who measured the X-ray diffraction patterns of cellulose immersed into iodine solution and assigned one reflection of 9.0 Å spacing to the characteristic to the complex. But no detailed analysis was made, and their paper did not get much attention in these 60 years, resulting in the above-mentioned wrong and long legend. The present paper has succeeded for the first time to break through such a common sense and to establish the formation of crystalline cellulose-iodine complex by the detailed X-ray structure analysis.

The influence of acid hydrolysis followed by autoclaving-cooling on physical properties and resistant starch of purple sweet potato (Ipomea batatas L.) flour

In this study influence of acid hydrolysis using HCl 2% followed by autoclaving-cooling at 121°C for 15 minutes and cooled at 5°C for 72 hours with two repetition cycles on resistant starch of purple sweet potato flour were investigated and physical properties were analyzed. This treatment exhibited beneficial impacts of modified flour on resistant starch formation by 14.35%. Significant difference was exhibited between native and modified flour for ΔE value. Rapid visco analyzer was also used to determine pasting properties including peak viscocity, trough viscocity, breakdown, final viscosity, setback, and peak time where all of them except breakdown value were higher than the native one. Moreover, no signs of damage on the surface of native purple sweet potato flour were showed in micrograph of scanning electron microscopy. While autoclaving-cooling sample exhibited a rough structure as a result of the loss of its granular appearance and destroyed shape. This study also indicated a change of X-ray diffraction pattern from C-type to B-type caused by the modification treatment.

In‐situ transformation of iron‐bearing minerals in marshland‐derived paddy subsoil

Transformations of Fe‐bearing minerals under alternating redox conditions are not fully understood. In‐situ approaches under field conditions have rarely been used. We exposed mesh bags containing ferrihydrite, goethite or nontronite to changing redox conditions in subsoil that had been under paddy management for 100, 700 and 2000 years. After 12 months, the minerals were retrieved and analysed for organic carbon and by X‐ray diffraction; in addition, nontronite was analysed for cation exchange capacity and by Mössbauer spectroscopy at 278 and 4.2 K. Field exposure of the test minerals was complemented by measurements of soil redox potential and analyses of soil water. Minerals accumulated little organic carbon because of high pH and salinity. Goethite samples showed no changes in X‐ray diffraction patterns; therefore, they did not undergo detectable transformation, despite redox potentials frequently around −200 mV. Ferrihydrite transformed into more crystalline oxides, such as lepidocrocite, goethite and haematite. The extent of transformation, presumably by Fe2+‐catalysed recrystallization, increased with the time the soil had been under paddy management. Nontronite samples showed striking changes in surface colour, but no changes in X‐ray diffraction patterns or in cation exchange capacity. However, Mössbauer spectroscopy gave clear indications of irreversible changes within the nontronite crystal structure. Such changes have so far been observed only with chemical reduction, but it seems that they can occur under natural conditions. The results show that the overall redox status of a soil (i.e. the number of redox cycles it has undergone before) governs the extent and direction of mineral transformations during following redox cycles.HighlightsHow do ferrihydrite, goethite and nontronite transform under strongly alternating redox conditions? In‐situ exposure of minerals in soil under paddy management for 100, 700 and 2000 years. Fe2+‐catalysed ferrihydrite transformation; irreversible changes in nontronite crystal structure. The number of redox cycles a soil undergoes, governs mineral transformations in later redox cycles.

Effect of PFM Firing Cycles on the Mechanical Properties, Phase Composition, and Microstructure of Nickel‐Chromium Alloy

The purpose of this study was to compare the mechanical properties of beryllium-free nickel-chromium (Ni-Cr) dental casting alloy before and after each porcelain firing cycle (once fired, twice fired, and thrice fired) and to relate these properties to the microstructural changes and changes in X-ray diffraction patterns of Ni-Cr alloy that occur after each porcelain firing cycle. Forty tensile bar specimens and 20 disc-shaped specimens of Ni-Cr alloy were prepared. These specimens were divided into four groups. The first group was not heat treated and tested in the as-cast condition, thus serving as control group. The second, third, and fourth groups were fired once, twice, and thrice, respectively. Tensile bar specimens were loaded to failure in tension using a universal testing machine. Values of ultimate tensile strength, 0.1% yield strength, and percentage elongations were determined. Microstructural study and hardness testing were done using an optical microscope and digital Vickers hardness tester, respectively, on disc-shaped specimens. Disc-shaped specimens were again used to obtain the X-ray diffraction patterns by using diffractometer Bruker D8 focus. Statistical comparisons of the mechanical properties and hardness of the alloy were made with ANOVA. Intergroup comparisons of the data in the as-cast and fired specimens were analyzed by applying Tukey's HSD multiple comparison tests. Before porcelain firing, the alloy exhibited higher ultimate tensile strength (548 MPa), 0.1% yield strength (327 MPa), hardness (192 HV), and lower elongation values (18%). After each firing cycle, there was a significant (p < 0.001) decrease in ultimate strength (464 MPa for three times fired specimens), 0.1% yield strength (284 MPa for three times fired group), and hardness (164 HV for three times fired group) and significant (p < 0.001) increase in elongation value (28% for three times fired group) of Ni-Cr alloy. The microstructure of the control group specimen exhibited heterogeneous microstructure, and after each firing, microstructure of the alloy was gradually homogenized by formation of grain boundaries at the interdendritic interfaces. X-ray diffraction pattern shows that the alloy exhibited four strong diffraction peaks within the range of 2θ = 40° to 100°. After a third firing, intensity of these planes increased. Results of this study confirmed that nickel-based alloys become weaker after each firing process. After firing treatment, the microstructure of alloys showed decreased dendritic structure (i.e., homogenization, which was responsible for decrease in strength and an increase in ductility of the alloy); however, this decreased strength and hardness of Ni-Cr alloy after heat treatment was still superior to those of the most noble metal alloys used in dentistry. X-ray diffraction study showed that firing process led to relieving of stresses, which ultimately resulted in stability in the crystal structure of alloy.

Development of an x-ray diffraction camera used in magnetic fields up to 10 T

A high-field x-ray diffraction (HF-XRD) camera was developed to observe structural changes of magnetic materials in magnetic fields up to 10 T. The instrument mainly consists of a Debye-Scherrer-type camera with a diameter of 80.1 mm, a 10-T cryocooled superconducting magnet with a 100-mm room-temperature bore, an x-ray source, a power supply, and a chiller for the x-ray source. An x-ray detector (image plate) in the HF-XRD camera can be taken out and inserted into the magnet without changing the sample position. The performance of the instrument was tested by measuring the HF-XRD for silicon and ferromagnetic MnBi powders. A change of x-ray diffraction pattern was observed due to the magnetic orientation of MnBi, showing that the instrument is useful for studying field-induced orientation processes and structural properties of field-controlled materials.

Stability and equation of state of a nanocrystalline Ga-Ge mullite in a vitroceramic composite: A synchrotron x-ray diffraction study

Synchrotron x-ray diffraction and diamond anvil cell techniques were used to characterize the phase transformations and to evaluate the structural stability at elevated pressures of a developed nanocrystalline composite. The optically transparent material was built of a germanium oxide-based amorphous host matrix with homogeneously dispersed $13\ifmmode\pm\else\textpm\fi{}3\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ Ga-Ge mullite-type nanocrystals, which had a structure similar to the conventional ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{2}$ mullite. The equation of state of the nanocrystals and the overall structural integrity of the nanocomposite were investigated in quasihydrostatic conditions on compression to $36\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and on the following decompression to ambient conditions. The overall pressure-induced changes of x-ray diffraction patterns evidenced that the structural integrity of the material is well preserved up to about $14--16\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. The nanocomposite decompressed from $36\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ to ambient pressure showed a very limited reversibility of the pressure-driven changes. A Birch-Murnaghan fit of the unit cell volume as a function of pressure yielded a zero-pressure bulk modulus, ${K}_{0}$, for the nanocrystalline phase of $229(15)\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ which makes this material potentially interesting for structural applications at elevated pressures.

Optical Characterization of Titanium–Vanadium Oxide Films

Composite thin films of titanium and vanadium oxides (TVO) with various compositions were deposited by rf magnetron sputtering. The TVO films, of which their crystalline structure, composition, and film morphology were characterized, were examined to determine the optical constants and thermochromic performance as a function of the compositional ratio. The optical constants were determined by ellipsometric analysis using a consistent model of the film structure, and it was found that optical constants at visible and near-infrared wavelengths monotonically decrease from the values of VO2 towards those of TiO2 with an increase in Ti content in the TVO. The gradual depression of thermochromic performance with an increase in Ti content was measured. The change in X-ray diffraction pattern with the compositional ratio suggests that VO2 and TiO2 in the TVO film form a solid solution, or in other words the TVO can be expressed by TixV1-xO2.

Phase transformation in FeO under deep mantle conditions

Numerous studies have been made on the phase transformation in FeO under deep mantle conditions. However, the results are still controversial. We have studied the transition using both powdered FeO and single crystal of olivine-structured Fe2SiO4(fayalite) as starting materials. High pressure and high temperature in situ X-ray diffraction studies were carried out at the Photo Factory, Tsukuba, to clarify the stability of B1-B8-rhombohedral phase boundaries. Basic results are consistent with that reported by Kondo et al. [1]. In order to get homogeneous Debye rings of the high-pressure phase of FeO, single crystal of fayalite was used as starting material. Sudden change in color accompanied with the change in X-ray diffraction pattern was observed during room temperature compression at around 30 GPa. Clear diffraction spots from crystalline phase were observed even at 80 GPa. This result is in contrast with the previous report that powdered fayalite becomes amorphous at around 40 GPa when compressed at room temperature [2, 3].

829 X 線回折援用引張り試験装置の開発による MEMS 材料の機械的性質評価

This paper presents the development of tensile test technique for evaluation of elastic properties of MEMS materials in order to reliably design MEMS. A compact tensile tester operating in X-ray diffraction system was newly developed to measure Young's modulus, Poisson's ratio and fracture strength of micro-sized single/poly crystalline materials. Changes of X-ray diffraction patterns with increasing a tensile stress directly derived lateral strains of single crystal silicon (Si) specimens. Averaged value of Young's modulus and Poisson's ratio of the specimens was 168 GPa and 0.270,respectively, in agreement with analytical values calculated from anisotropic theory. This technique has, therefore, great potential for evaluating mechanical properties of micro-sized materials.

Microhardness characterization of Al–W thin films

Thin films of Al–W alloys were prepared on sapphire substrates by magnetron co-sputtering. By X-ray diffraction, it was revealed that, within a composition range Al 80W 20 to Al 67W 33, the films were amorphous. The increase of tungsten content in the films (Al 60W 40 and Al 50W 50) resulted in the appearance in a mixture of two or three metastable crystalline phases. Apparently, the mixture of crystalline phases co-existed with a small fraction of an amorphous one. Vickers microhardness of the as-prepared films varied from ∼11 GPa for completely amorphous up to ∼20 GPa for the films consisting of a mixture of phases. The thermal stability of films was investigated after isochronal annealing the samples for 1 h in a temperature range from 293 to 1273 K. It was revealed that there was slight increase in the microhardness during annealing up to a temperature chosen within the interval ∼773–848 K, and such annealing has a small influence on the XRD patterns. In contrast, the annealing above this temperature interval induced detectable changes in the microhardness and significant changes in X-ray diffraction patterns. The results of analysis of XRD patterns demonstrated that amorphous thin films do not disintegrate directly into the ordered equilibrium ( α-W, Al 4W, and Al 5W) co-existing phases, but the metastable ( α-W(Al), β-W(Al), and Al(W)) intermediary phases were observed to appear in the films before the former phases were observed. Thus, for the microhardess behaviour during isochronal annealing of Al–W thin films an explanation given for the metallic glasses investigated earlier can be offered, and this explanation is based also on the results of the XRD investigation we performed.

Photo-irradiation induced morphological changes in nylon 66

Nylon 66 films were photo-irradiated at 60°C for different time intervals up to 200h. Photo-irradiated samples were characterized by XRD, DSC and optical microscopy. XRD results showed that there was increase in crystallinity with increase in exposure time during initial period of photo-exposure. However, there was no change in X-ray diffraction pattern upon photo-irradiation. DSC results showed that there was formation of new crystalline morphology upon photo-irradiation. This formation of new crystalline morphology was observed to be at the expense of existing morphology. Optical microscopy showed that there was formation of cracks at the center of spherulites as photo-irradiation proceeds. Cracks were increased in size with photo-irradiation.

1503 急冷凝固 Ti-Pd-Ni 形状記憶合金の物性

Shape memory ally Ti-Pd-Ni films were made by the melt spinning apparatus with a single roll of rapid solidification method. Obtained specimens were ribbon shaped films, 20&acd;30μm in thickness and 1mm in width. The structures of the surfaces were observed by an optical microscope. The crystal structures at various temperatures were studied by the X-ray diffraction. Preferred crystal orientation was observed in these films. The martensitic and the reverse martensitic transformation temperatures were determined by the temperature changes of X-ray diffraction patterns and a differential scanning calorimeter. These transformation temperatures were lower than that of bulk specimens. After annealing at 800℃, these transformation temperatures did not increase up to that of bulk specimens.

The Changes of PP Crystal Orientation in the Polypropylene/Polyamide 6 Blend Fiber by Annealing.

The changes of X-ray diffraction patterns with annealing were investigated for polypropylene/polyamide 6 (hereafter “PP/PA6”) blend fibers. An annealing under a free end at the melting point of PP or higher, induced the extreme reduction of the c-axis orientation of PP crystal, and the development of anisotropic a*-axis orientation. In the samples annealed under a constant length or the samples with low heat shrinkage, the c-axis orientation of PP crystal remained unchanged and the a*-axis orientation was developed. X-ray diffraction patterns of the blend fiber during heating revealed that the diffraction peak of PP crystal completely disappeared around 170°C or higher, although the blend fiber annealed at a constant length for two hours at 200°C, showed a clear c-axis orientation of PP crystal.It is inferred that the PP crystals melt during annealing of the blend fiber at the melting point of PP or higher. Since the oriented PA6 phases keep their macroscopic shape during annealing, molecular chains of PP can't form a random coil but partly keep the original orientation which might enhance an anisotropic c-axis orientation.

Crystal structure of hydride and deuteride of unial

The hydrogen and deuterium absorption behaviour of UNiAl was examined at hydrogen isotope pressures below 10 5 Pa and temperatures up to 973 K. Under these conditions UNiAl absorbed hydrogen and deuterium up to UNiAlH 0.8 and UNiAlD 0.7 respectively. Neutron powder diffraction of UNiAlD 0.7 revealed that each D atom occupies a 3U-2Ni site formed by three U atoms and two Ni atoms. It is at the centre of a triangle of U atoms which two 3U-1Ni-type tetrahedral sites share. This occupation slightly changed the arrangement of metal atoms to enlarge the 3U triangle. Changes in X-ray diffraction pattern suggested the further movement of metallic atoms to form UNiAlH 2.7.

Structure and properties of boron/aluminium composites

The influence of heat treatment on the structure and strength of boron/aluminium composites has been studied. Matrix material around a fibre is assumed to be hardened by dispersed particles of boron-containing compounds, presumably magnesium borides. Such a material is expected to have higher yield strength and greater brittleness compared to the original matrix material. A fibre and its surrounding zone is a prospective site of microcracking under loading. These zones grow as heat treatment proceeds. When neighbouring zones become linked to each other, the size of a possible brittle microcrack is doubled and a fall in the composite strength follows. A corresponding microstructural model of the composite failure is constructed. Without having direct observation of magnesium borides, the model of composite behaviour is supported by (i) dependence of the composite strength on the size of the influence zone; (ii) dependence of the strength on the effective time, the latter being determined by the activation energy of magnesium diffusion in aluminium; (iii) observation of failure surfaces of composites subjected to various heat treatments; and (iv) a correlation of changes of matrix state detected by changes in X-ray diffraction patterns with a hypothetical picture of the development of the influence zones.

板谷ゼオライトおよびその改質物の物理化学的性質と気体の吸着分離特性

Itaya natural zeolite and its cation-treated zeolite were characterized by X-ray diffraction, thermo-gravimetric analysis, adsorption and chemical analysis. No change of X-ray diffraction pattern was found for Itaya zeolites treated with 1mol·dm-3 hydrochloric acid but a slight change of SiO2/Al2O3 ratio was found.The surface of Itaya zeolite seem to contain both meso- or macropores, but its heterogeneous surface became homogeneous with hydrochloric acid treatment, being predominantly composed of micropores. The monolayer adsorption capacity of zeolite for nitrogen gas decreased as the amount of cations in the Itaya zeolite increased. The cation (Na+, K+, NH+4, Ca2+) exchanged Itaya zeolite samples had less nitrogen adsorbing power than the hydrochloric acid-treated zeolite.The gas separation behaviour of Itaya zeolite was compared with that of the cation-treated zeolite. Separation of hydrogen, oxygen, nitrogen, methane and carbon monoxide from the surface of zeolites was investigated at 30-100°C by using Itaya zeolite and its cation-treated zeolite as column packings. Hydrogen, oxygen, nitrogen, carbon monoxide and methane were found to be separatable completely from the mixture gases by using Itaya zeolite, hydrochloric acid treated zeolite and its K+ exchange zeolites. A methane-oxygen mixture could not be separated by Na+, NH+4 and Ca2+ exchanged Itaya zeolites.