Intracrystalline Structure Research Articles

Biomineralized Materials as Model Systems for Structural Composites: Intracrystalline Structural Features and Their Strengthening and Toughening Mechanisms.

Biomineralized composites, which are usually composed of microscopic mineral building blocks organized in 3D intercrystalline organic matrices, have evolved unique structural designs to fulfill mechanical and other biological functionalities. While it has been well recognized that the intricate architectural designs of biomineralized composites contribute to their remarkable mechanical performance, the structural features within and corresponding mechanical properties of individual mineral building blocks are often less appreciated in the context of bio‐inspired structural composites. The mineral building blocks in biomineralized composites exhibit a variety of salient intracrystalline structural features, such as, organic inclusions, inorganic impurities (or trace elements), crystalline features (e.g., amorphous phases, single crystals, splitting crystals, polycrystals, and nanograins), residual stress/strain, and twinning, which significantly modify the mechanical properties of biogenic minerals. In this review, recent progress in elucidating the intracrystalline structural features of three most common biomineral systems (calcite, aragonite, and hydroxyapatite) and their corresponding mechanical significance are discussed. Future research directions and corresponding challenges are proposed and discussed, such as the advanced structural characterizations and formation mechanisms of intracrystalline structures in biominerals, amorphous biominerals, and bio‐inspired synthesis.

Novel Composites of Multifunctional NaP Zeolite/Graphene Oxide for Highly Efficient Removal of Fe(III) from Aqueous Solution

Composites of graphene oxide (GO, 1–5 wt%) loaded into the inter pores of the hollow NaP zeolite at 100 °C were successfully prepared via the zeolite synthesis method (ZSM). These NaP/GO composites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and N2 physisorption analysis. The structural properties of NaP/GO (1–3 wt%) indicated that GO moieties can be accommodated in the voids of the NaP zeolite without modifying its framework or structure. The FE-SEM image of NaP/GO (3 wt%) showed the tendency of GO to form significantly smaller individual particles of NaP zeolite than corresponding of NaP/GO (1 and 2 wt%). The FTIR band due to asymmetric stretching T–O lattice vibration (~ 1000 cm−1) was shifted towards higher frequencies with increasing content of GO (1–3 wt%), reflecting the involvement of GO adducts in the intracrystalline structure of NaP zeolite. The produced composites were used for the removal of Fe(III) ions from aqueous solution and such process took place via a surface uptake and intra-particle diffusion which operate simultaneously through the interaction between Fe(III) ions and NaP/GO (3 wt%). The dielectric constant (er) values as a function of frequency were increased after adsorbing Fe(III) onto NaP/GO (3 wt%) which may be attributed to cations hopping diffusion along zeolite structure.

Critical Role of the Chemical Environment of Interlayer Na Sites: An Effective Way To Improve the Na Ion Electrode Activity of Layered Titanate.

The chemical environments of the interlayer Na sites of layered titanate are finely controlled by the intercalation of n-alkylamine with various alkyl chain lengths to explore an effective way to improve its electrode functionality for sodium-ion batteries (SIBs). The n-alkylamine intercalation via ion-exchange and exfoliation-restacking routes allows the modification of in-plane structures of layered titanate to be tuned. Among the present n-alkylamine-intercalates, the n-pentylamine-intercalated titanate shows the largest discharge capacity with the best rate characteristics, underscoring the critical role of optimized intracrystalline structure in improving the SIB electrode performance of layered titanate. The creation of turbostratic in-plane structure degrades the SIB electrode performance of layered titanate, indicating the detrimental effect of in-plane structural disorder on electrode activity. 23Na magic-angle spinning nuclear magnetic resonance spectroscopy demonstrates that the n-alkylamine-intercalated titanates possess two different interlayer Na+ sites near ammonium head groups/titanate layers and near alkyl chains. The intercalation of long-chain molecules increases the population of the latter site and the overall mobility of Na+ ions, which is responsible for the improvement of electrode activity upon n-alkylamine intercalation. The present study highlights that the increased population of interlayer metal sites remote from the host layers is effective in improving the electrode functionality of layered metal oxide for SIBs and multivalent ion batteries.

Effect of cerium ions initial distribution on the crystalline structure and catalytic performance of CeY zeolite

Effect of cerium ions initial distribution on the crystalline structure and catalytic performance of CeY zeolite

Further evidence of phase formation through a liquid state stage in metals being electrodeposited: Part 2

The phenomenon of phase formation through a liquid state stage in metals being electrodeposited has been discussed. In order to provide further evidence on the existence of this phenomenon, a set of experiments are conducted to reveal the predicted structural features in metals exposed to a minor external force during electrodeposition. In the second part of the research, the results of structural studies of metals electrodeposited under the action of an external force directed perpendicular to the crystallization front are discussed. It is found that electrodeposition of metals exposed to a minor external force perpendicular to the crystallization front leads to a refinement of their intracrystalline structure and surface morphology. The experimental results prove the existence of the phenomenon of phase formation through a liquid state stage in metals being electrodeposited.

Molecular Orientation of Intercalants Stabilized in the Interlayer Space of Layered Ceramics: 1-D Electron Density Simulation

In this review, an attempt is made to calculate one-dimensional (1-D) electron density profiles from experimentally determined (00l) XRD intensities and possible structural models as well in an effort to understand the collective intracrystalline structures of intercalant molecules of two-dimensional (2-D) nanohybrids with heterostructures. 2-D ceramics, including layered metal oxides and clays, have received much attention due to their potential applicability as catalysts, electrodes, stabilizing agents, and drug delivery systems. 2-D nanohybrids based on such layered ceramics with various heterostructures have been realized through intercalation reactions. In general, the physico-chemical properties of such 2-D nanohybrids are strongly correlated with their heterostructures, but it is not easy to solve the crystal structures due to their low crystallinity and high anisotropic nature. However, the powder X-ray diffraction (XRD) analysis method is thought to be the most powerful means of understanding the interlayer structures of intercalant molecules. If a proper number of well-developed (00l) XRD peaks are available for such 2-D nanohybrids, the 1-D electron density along the crystallographic c-axis can be calculated via a Fourier transform analysis to obtain structural information about the orientations and arrangements of guest species in the interlayer space.

Intracrystalline structure and release pattern of ferulic acid intercalated into layered double hydroxide through various synthesis routes

Intracrystalline structure and release pattern of ferulic acid intercalated into layered double hydroxide through various synthesis routes

Intercalative Ion‐Exchange Route to Amino Acid Layered Double Hydroxide Nanohybrids and Their Sorption Properties

AbstractA soft chemical route to amino acid layered double hydroxide (LDH) nanohybrids was demonstrated on the basis of an intercalative ion‐exchange reaction. Two different amino acids, phenylalanine and glutamic acid, were intercalated and stabilized in the interlayer space of a 2‐dimensional double hydroxide lattice by electrostatic interaction. An attempt was also made to understand the effect of the intracrystalline structure of the amino acid in the LDH on the specific surface area, porosity, and gas sorption properties of the hybrid. According to the X‐ray diffraction analysis, the basal spacings of LDH intercalated with phenylalanine and LDH intercalated with glutamic acid were expanded to 1.80 and 1.22 nm, respectively, relative to that of the pristine Mg2Al‐NO3‐LDH (0.88 nm), which indicates that amino acid molecules were successfully intercalated into the LDH. Fourier transform infrared spectra for both samples confirmed that the carboxylic acid group in the amino acid is anionic carboxylate under basic conditions and it eventually interacts with the positively charged LDH surface. From N2 adsorption/desorption analysis, the BET specific surface area of the LDH intercalated with phenylalanine was found to be twice as large as that for the LDH intercalated with glutamic acid. However, the CO2 adsorption capacity of the former was determined to be three times more enhanced than that of the latter, due to an enhanced specific surface area and effective amine sites to form carbamates.

Study on Toughening Mechanism of Nano-Composite Ceramics Prepared by Mixed Coagulative Method

In this work the toughening mechanism and the microstructure of SPS-sintered Al2O3-ZrO2 nano-composite ceramics whose powder was prepared by mixed coagulative method, was studied. The study showed that the grain shape of Al2O3 was changed due to the additive ZrO2 and its density was improved in the Al2O3- ZrO2 ceramics. Meanwhile its grain was refined. The microstructure was the typical nano-composite ceramics mixed with intracrystalline and intercrystalline structure. The irregular aggregation of ZrO2 mostly existed on the grain boundary, where many grains of Al2O3 intersected. Some thin and dispersal globular nano grains (70nm-200nm) of ZrO2 were distributed in the Al2O3 crystal grains. That enhanced the mechanical performance of the matrix because of the refined grain and the intracrystalline nanometer structure. The study also showed that the changes of the mechanical performance of Al2O3-ZrO2(n) ceramic resulted from toughening mechanism introduced by nanometer grains, toughening mechanism introduced by ZrO2 phase transition and the intracrystalline structure.

Intracrystalline structure of DNA molecules stabilized in the layered double hydroxide

Intracrystalline structure of DNA molecules stabilized in the layered double hydroxide

Intracrystalline Structure and Physicochemical Properties of Mixed SiO2−TiO2 Sol-Pillared Aluminosilicate

Highly porous layered inorganic-inorganic nanohybrids were prepared by pillaring SiO2-TiO2 nanosol particles with aluminosilicate layers. According to powder X-ray diffraction analysis, the basal spacing of SiO2-TiO2 pillared aluminosilicate (STPC) calcined at 400 degrees C was determined to be larger than 40 A. N2 adsorption-desorption isotherm measurements showed the STPC to have a large Brunauer-Emmett-Teller surface area of approximately 590 m2/g, of which approximately 70% originates from micropores with a size range of 8-16 A. The sorption behavior of various solvent vapors such as hexane, methanol, and water reveals internal pore surfaces of the STPC to be hydrophobic. A distinct blue shift of absorption edge in UV-vis spectra clearly demonstrates that the nanosized TiO2 particles are formed between silicate layers as a pillar. Fourier transform infrared and extended X-ray absorption fine structure analysis at the Ti K edge reveals that the pillared titania exists in the form of anatase-structured TiO2 nanocrystals, not in the form of covalently bonded mixed particles of TiO2-SiO2. On the basis of the present findings, we are able to conclude that the quantum-sized TiO2 and SiO2 particles are independently intercalated to form a multilayer stacking intracrystalline structure in the gallery space of aluminosilicate clay.

A new cointercalated superconducting bismuth cuprate, (HgI2)0.5I0.5Bi1.85Pb0.35Sr1.9Ca2.1Cu3.1O10 + δ

Intercalation of HgI2 into high-Tc superconducting Bi1.85Pb0.35Sr1.9Ca2.1Cu3.1O10 + δ (Bi2223) compound is achieved by a stepwise reaction technique in which the iodine intercalate is used as a secondary host material. While the vapor transport reaction is ineffective in intercalating mercuric salts directly into Pb-doped or single crystalline Bi-based cuprates, the present stepwise reaction method can provide a useful way of intercalating larger molecules into Bi2O2 double layers of Bi-based cuprates. According to Hg LIII-edge extended X-ray absorption fine structure analyses, it is found that the intercalated mercuric iodide is stabilized as a linear molecule with additional free iodine species in the interlayer space of Bi2223. Taking into account the fact that no free iodine can be found in the HgI2 intercalated Bi2Sr2CaCu2O8+δ polycrystal prepared by the direct intercalation method, the present experimental finding indicates that the intracrystalline structure of mercuric iodides in Bi2O2 double layers can be modified by controlling the synthetic route. The linear geometry of intercalated mercuric iodide has been further confirmed by performing ex-situ X-ray diffraction measurements on the deintercalation products, which clarify that the partial deintercalation of mercuric iodide leads to the formation of an intermediate phase with a parallel orientation of HgI2 molecules with respect to the basal plane.

Highly Reactive Remelted Belite

Remelted belite showed higher hydration activity and better grindability than the quenched material. Both properties were closely related to the belite microtextures induced by the remelting reaction; after the reaction, the belite showed disintegration of the intracrystalline lamella structure, inclusion of the liquid exsolved on the former lamella boundaries, and crystallization of the liquid during further cooling. The fractures easily penetrated the remelted crystal grains upon grinding, probably along the disintegrated lamella boundaries and/or along the inclusions. The resulting fragments were irregular in shape with high specific surface area, leading to the high hydration activity of the remelted belite.

Superionic and Superconducting Nanohybrids with Heterostructure, AgxIwBi2Sr2Can-1CunOy(0.76 ≤x≤ 1.17,n= 1, 2, and 3)

New mixed conducting hybrid systems, AgxIwBi2Sr2Can-1CunOy (n = 1, 2, and 3), have been developed successfully by intercalating the superionic conducting Ag−I layer into the superconducting Bi2Sr2Can-1CunOy lattice. Although the Ag−I intercalation gives rise to a remarkable basal increment of ∼7.3 Å, which is twice as large as that of the iodine intercalate (Δd = 3.6 Å), it has little influence on the superconducting property with only a slight Tc depression. Systematic X-ray absorption near edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) studies clearly reveal the charge transfer between host and guest, indicating that a change in hole concentration of the CuO2 layer is the main origin of Tc evolution upon intercalation. According to the ac impedance and dc relaxation analyses, the AgxIwBi2Sr2Can-1CunOy compounds possess fast ionic conductivities (σi = 10-1.4−10-2.6 Ω-1 cm-1 at 270 °C) with the activation energies of 0.22 ± 0.02 eV, which are similar to those of other two-dimensional Ag+ superionic conductors. A more interesting finding is that these intercalates exhibit both high electronic and ionic conductivities with ionic transference numbers of ti = 0.02−0.60, due to their interstratified heterostructures consisting of a superionic conducting silver iodide layer and a metallic host layer. A close relationship between local crystal structure and ionic conductivity has been elucidated from the detailed Ag K-edge EXAFS analyses, where a reasonable pathway for Ag+ ionic conduction is suggested along with the intracrystalline structure of the Ag−I sublattice.

Creation and early history of the Institute of Engineering Mechanics of the National Academy of Sciences of Ukraine

The Institute of Engineering Mechanics (IEM) of the National Academy of Sciences of Ukraine is one of the youngest institutes in the Mechanics Division of the Academy, but more than 30 years have already passed since its founding. Academician Mikhail Kuz'mich Yangel' was one of the organizers of the Institute. Yangel clearly understood that the development of rocket and space technology should be based on the latest advances in basic and applied research on engine design, heat and mass transfer, thermal insulation, aerodynamics and gasdynamics, new materials and technologies, strength and reliability, the optimization of structures, and other disciplines. To solve problems related to rocket design, he enlisted the support of a wide range of academic and sector institutes in the former USSR. Among them were institutes under the Academy of Sciences of the Ukrainian SSR (AS USSR), doing research in electric welding, mechanics, strength problems, materials science, ultrahard materials, and other areas. At the initiative ofM. K. Yangel', in April 1966 a new academic unit was organized in Dnepropetrovsk -- the Section on Problems of Engineering Mechanics. The new unit was part of the Dnepropetrovsk Branch of the Institute of Mechanics of the AS USSR. The staff of the unit was initially composed mainly of specialists from the "Yuzhnoe" (Southern) Design Office. By 1966 the unit had four divisions: aerodynamics, engine dynamics, ballistics and control, and aircraft reliability. These divisions were headed by AS USSR Corresponding Member Vyacheslav Miklmilovich Kovtunenko and AS USSR Academician Vladimir Ivanovich Mossakovskii on a voluntaD, basis. The first director of the Section, also a volunteer, was Nikolai Fedorovich Gerasyuta. Gerasyuta Idled out the staff of the new divisions and planned the research that was to be carded out by the Section. In a relatively short time, the Section became an almost independent unit with a well-defined scientific focus. The next stage in the organization of the IEM was the transformation of the Section on Problems of Engineering Mechanics into the Dnepropetrovsk Branch of the Institute of Mechanics of the Academy of Sciences of the Ukraine in April of 1968. Vsevolod Amtyunovich l.~Taryan, then a Corresponding Member of the AS USSR, was chosen to be the director of the Branch. Its main areas of research were as follows: aerogasdynamics of aircraft; dynamic processes in engines and pneumatic-hydraulic systems; mechanics of machines; applied meclmnics of nonlinear systems; ballistics and control of aircraft; aircraft reliability. The range of subjects studied at the Branch rapidly expanded. The organization absorbed the physics and metallurgy departments of the former Kharkov Branch of the Physicotechnical Institute of Low Temperatures and took on research responsibilities in new areas: mechanics of high-speed motion on the ground; intmcrystalline structure of metals and alloys; physical principles of formation of the structure of alloys; semiconductor electronics; physical metallurgy. The Dnepropetrovsk Branch of the Institute of Mechanics was also restructured into 11 departments: aerogasdynamics of aircraft; dynamics of aircraft engines; mechanics of machines; applied mechanics of nonlinear systems; ballistics and control of aircraft; aircraft reliability; mechanics of high-speed motion on the ground; intracrystalline structure of metals and alloys; physical principles of formation of the structure of alloys; semiconductor electronics; physical metallurgy. The volume of research being done at the Branch grew with each new year, making it necessary to create more

Nucleation and growth of Pd clusters in mordenite

Nucleation and growth of Pd clusters in mordenite

ChemInform Abstract: Intracrystalline Structure of Molecular Mercury Halide Intercalated in High‐Tc Superconducting Lattice of Bi2Sr2CaCu2Oy.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Molecular layer-by-layer engineering of superconducting and superionic materials in the (AgI)Bi2Sr2CaCu2Oy system

We have developed a new interstratified system consisting of a superconducting layer alternating with a superionic conducting one, which is the AgI intercalated Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} with well-defined 2-dimensional heterostructure. Before and after the intercalation of AgI, the superconducting properties remained unchanged with the T{sub c}`s of 76 K for the pristine and 63 K for the intercalate. From the extended X-ray absorption fine structure spectroscopic analysis, it is found that the intercalated AgI is formed as the {beta}-like intracrystalline structure in the 2-dimensional interlayer space of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y}. According to the ac impedance and dc relaxation measurements, the ionic transference number (t{sub i} = {sigma}{sub i}/{sigma}{sub r}) has been estimated to be 0.27 (at 167{degree}C), indicating that the substantial ionic conductivity ({sigma}{sub 1}) contributes to the total electrical one ({sigma}{sub T}). In comparison of the ionic conductivity for (AgI)Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} ({sigma}{sub i} = 10{sup -3}-10{sup -23} {Omega}{sup -1} cm{sup -1}) with those for the well-known superionic conductors of cation-substituted {beta}-aluminas, the ionic transport in (AgI)Bi{sub 2}Sr{sub 2}-CaCu{sub 2}O{sub y} turned out to be significant, even comparable with the superionic conductors. 15 refs., 4 figs., 1 tab.

Infrared diffuse reflectance study of the silicon-rich H-ZSM-5 catalysis of ethanol conversion

Infrared diffuse reflectance study of the silicon-rich H-ZSM-5 catalysis of ethanol conversion

Intracrystalline structure of enamel crystals affected by caries.

Enamel crystals in the demineralized zones in early caries lesions of human teeth were observed by high-resolution electron microscopy. The enamel crystals frequently exhibited perforations in their centers and defects of various sizes on their lateral surfaces. There were a number of small electron-lucent spots, suggesting that the dissolution of crystals had taken place there. These spots were in especially large numbers near the central dark line. The central perforations, the lateral defects, and the small spots had a common habit which formed regularly along the crystalline a- and b-axes. In many cases, when the central dark line was seen, the perforations were located a few unit cells away from the line. The perforations seem to result from a fusion of small spots, which enlarge by involving other small spots. The lateral defect seemed to enlarge by removal of unit cells and progression along the a- and b-axes. In the regions where the small spots were present, however, the enlargement of the defects also progressed involving the spots. The central dark line seems to be rather resistant to dissolution. One of the main factors for the central perforation of the crystals is thought to be the presence there of especially large numbers of defective sites.