Expansion Of Lattice Spacing Research Articles

Regulating the intrinsic electronic structure of carbon nanofibers with high-spin state Ni for sodium storage with high-power density

Carbon nanofibers (CNFs) with high specific surface area show great potential for sodium storage as a hard carbon material. Herein, CNFs anchored with Ni nanoparticles (CNFs/Ni) were prepared through chemical vapor deposition and impregnation reduction methods, in situ growing on the three-dimensional porous copper current collector (3DP-Cu). The coupling effect of high-spin state Ni nanoparticles leads to the increase of defect density and the expansion of lattice spacing of CNFs. Meanwhile, the 3DP-Cu ensures a high loading capacity of CNFs and short ion/electron transport channels. As an integral binder-free anode, the 3DP-Cu/CNFs/Ni exhibits excellent electrochemical performance, which demonstrates a high specific capacity with 298.5 mAh g–1 at 1000 mA g–1 after 1500 cycles, and a high power density with 200 mAh g–1 over 1000 cycles at 5000 mA g–1. Density functional theory calculation results show that the high-spin state Ni regulates the electronic structure of CNFs, which significantly reduces the adsorption energy for Na+ (–2.7 Ev) and thus enables high-rate capability. The regulation of the electronic structure of carbon materials by high-spin state metal provides a new strategy for developing high-power carbonaceous anode materials for sodium-ion batteries.

Spinel ferrite-enhanced Cr(VI) removal performance of micro-scale zero-valent aluminum: Synergistic effects of oxide film destruction and lattice spacing expansion

Zero-valent aluminum (ZVAl) as a cost-effective additive with excellent reducibility is a promising material for application in heavy metal elimination. However, dense surface oxide films suppress the reactivity of ZVAl. Herein, we prepared mZVAl/MFe2O4 (M = Mn, Zn, Ni) composites via an accessible ball milling process and confirmed their satisfactory adsorption–reduction performance for Cr(VI) removal. The removal efficiency was not significantly affected by the changes in pH and presence of ions and humic acid. Direct spectroscopic analyses and density functional theory calculations revealed that ball milling with MFe2O4 destroyed the oxide film and increased the lattice spacing of mZVAl. The enhanced adsorption and reduction performances of ZVAl after ball milling was the primary reason for the improvement in Cr(VI) removal. This study presents a new pathway for the development of reductive materials for heavy metal removal in wastewater treatment.

Higher Conductivity and Enhanced Optoelectronic Properties of Chemically Grown Nd-Doped CaSnO3 Perovskite Oxide Thin Films.

Stannous-based perovskite oxide materials are regarded as an important class of transparent conductive oxides for various fields of application. Enhancing the properties of such materials and facilitating the synthesis process are considered major challenging aspects for proper device applications. In the present paper, a comprehensive and detailed study of the properties of spray-coated CaSnO3 thin films onto the Si(100) substrate is reported. In addition, the substrate effect and the incorporation of rare-earth Nd3+ on engineering the characteristics of CaSnO3 thin films annealed at 800 °C are included. X-ray diffraction (XRD) analysis results revealed the orthorhombic structure of all the samples with an expansion of lattice spacing as the substitution of Nd at the Ca site increased. The Raman and FT-IR analysis further confirmed the structural results collected via the XRD analysis. Surface scanning using field-emission scanning electron microscopy revealed the formation of quasi-orthorhombic CaSnO3 grains with an increase in size as dopant content increased. Energy-dispersive X-ray analysis allowed quantification of the elements, while atomic mapping permitted visualizing their distribution along the surfaces. UV–visible spectroscopy and first-principles calculations using density functional theory (DFT) were conducted, and a thorough investigation of the optical and electronic properties of the pure material upon Nd3+ insertion was provided. Electrical properties collected at room temperature revealed a growing conductivity upon doping ratio increase with a simultaneous enhancement in the carrier concentrations and mobility. The findings of the present work will help facilitate the synthesis procedure of large-area stannous-based perovskite oxide thin films through simple and efficient chemical solution methods for optoelectronic device applications.

Promotional effect of Mn-doping on the structure and performance of spinel ferrite microspheres for CO hydrogenation

A series of uniform microspheres of spinel-type Mn-doped ferrites (MnxFe3-xO4) with different Fe/Mn ratios were employed for the Fischer-Tropsch-to-olefins reaction (FTO). The highest selectivity of 54.4% and the space-time-yield (STY) of 73.0g·kgcat−1·h−1 to lower olefins (C2-4=) were achieved over an Fe-Mn catalyst with 13 wt% Mn. A panoramic view of structure evolution of MnxFe3-xO4 was revealed using multiple in/ex situ techniques. We demonstrated that the expansion of lattice spacing induced by Mn exerted remarkable effects on the stabilization of MnxFe1-xO and ε-Fe2C during activation and reaction. Moreover, Mn endows Fe catalysts with strong surface basicity and consequently enhances the adsorption and dissociation of CO; while weakening the H availability and readsorption of olefinic intermediates. In addition, the impeded carburization of MnxFe1-xO and the reduction in particle size of catalysts jointly contribute to the volcano curve in the catalytic activity. The insights presented could guide the rational design of high performance catalysts via heteroatom doping.

One-step hydrogen extraction and storage in plasma generated palladium nanoparticles

This study demonstrates a novel way of hydrogen extraction from toluene and direct storage in plasma generated palladium (Pd) nanoparticles in one-step. Monodispersed Pd nanoparticles with a narrow particle-size distribution have been successfully synthesized, for the first time, by a plasma discharge between Pd electrodes in the cavitation field of toluene. The resulting well-dispersed Pd nanoparticles embedded in carbon are stabilized against agglomeration. The effect of experiment time on the particle size and the expansion of lattice spacing due to hydrogen are investigated by experimental and computational studies using density functional theory (DFT). Using X-ray diffraction and high-resolution transmission electron microscopy measurements, it was found that particle size and lattice expansion increases with experiment time. Pd nanoparticle synthesis for in situ hydrogen storage in one step using plasma discharge in an appropriate solvent emphasizes the importance of adopting this methodology which offers several advantages. These include rapid reaction rate, ability to form very small nanoparticles with narrow size distribution and hydrogen extraction from the solvent for direct storage in the Pd nanoparticle lattice.

Depressed contractile performance and reduced fatigue resistance in single skinned fibers of soleus muscle after long-term disuse in rats

Long-term disuse results in atrophy in skeletal muscle, which is characterized by reduced functional capability, impaired locomotor condition, and reduced resistance to fatigue. Here we show how long-term disuse affects contractility and fatigue resistance in single fibers of soleus muscle taken from the hindlimb immobilization model of the rat. We found that long-term disuse results in depression of caffeine-induced transient contractions in saponin-treated single fibers. However, when normalized to maximal Ca(2+)-activated force, the magnitude of the transient contractions became similar to that in control fibers. Control experiments indicated that the active force depression in disused muscle is not coupled with isoform switching of myosin heavy chain or troponin, or with disruptions of sarcomere structure or excessive internal sarcomere shortening during contraction. In contrast, our electronmicroscopic observation supported our earlier observation that interfilament lattice spacing is expanded after disuse. Then, to investigate the molecular mechanism of the reduced fatigue resistance in disused muscle, we compared the inhibitory effects of inorganic phosphate (Pi) on maximal Ca(2+)-activated force in control vs. disused fibers. The effect of Pi was more pronounced in disused fibers, and it approached that observed in control fibers after osmotic compression. These results suggest that contractile depression in disuse results from the lowering of myofibrillar force-generating capacity, rather than from defective Ca(2+) mobilization, and the reduced resistance to fatigue is from an enhanced inhibitory effect of Pi coupled with a decrease in the number of attached cross bridges, presumably due to lattice spacing expansion.

Nitriding of Aluminium Alloy in Nitrogen and Nitrogen-Helium Mixture Using 100 Hz-Pulsed DC Glow Discharge

Nitriding of aluminium alloy (AlFe1.8Zn0.8) in nitrogen and nitrogen-helium mixture was carried out by using 100 Hz-pulsed DC glow discharge. Samples are treated for different durations, namely 4 h, 8 h and 12 h, in nitrogen plasma as well as in a mixture of nitrogen-helium plasma for the same processing duration of 4 h. All nitriding treatments are carried out at an input power of 100 W, filling pressure of 1 mbar and substrates temperature of 250oC. X-ray diffraction (XRD) results show an expansion in lattice spacing and consequently shift of diffraction peaks towards lower angle with the addition of helium in nitrogen plasma. Surface morphology of the treated sample is investigated by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Vickers micro-hardness testing results show increases in surface hardness with processing duration as well as with the addition of helium in nitrogen plasmas. This increase of surface hardness may be attributed to the diffusion of nitrogen content in the surface layer generating internal stresses. It is observed that the addition of helium positively affects the nitriding of samples.

Surface Channeling in Aberration-Corrected Scanning Transmission Electron Microscopy of Nanostructures

The aberration-corrected scanning transmission electron microscope can provide information on nanostructures with sub-Angström image resolution. The relatively intuitive interpretation of high-angle annular dark-field (HAADF) imaging technique makes it a popular tool to image a variety of samples and finds broad applications to characterizing nanostructures, especially when combined with electron energy-loss spectroscopy and X-ray energy-dispersive spectroscopy techniques. To quantitatively interpret HAADF images, however, requires full understanding of the various types of signals that contribute to the HAADF image contrast. We have observed significant intensity enhancement in HAADF images, and large expansion of lattice spacings, of surface atoms of atomically flat ZnO surfaces. The surface-resonance channeling effect, one of the electron-beam channeling phenomena in crystalline nanostructures, was invoked to explain the observed image intensity enhancement. A better understanding of the effect of electron beam channeling along surfaces or interfaces on HAADF image contrast may have implications for quantifying HAADF images and may provide new routes to utilize the channeling phenomenon to study surface structures with sub-Angström spatial resolution.

An inorganic–organic intercalated nanocomposite, BEDT-TTF into layered MnPS3

In this paper we report the synthesis and magnetic properties of an inorganic–organic hybrid, Mn0.84PS3(BEDT-TTF)0.35 (BEDT-TTF = bis(ethylenedithio) tetrathiafulvalene), which is obtained by the intercalation of pre-intercalation compound Mn0.90PS3(Phen)0.32 (Phen = 1,10-phenanthroline) with (BEDT-TTF)2Ix. The lattice spacing expansion (Δd) of 4.0 A compared with the pristine MnPS3 indicates that the molecular plane of BEDT-TTF is arranged parallel to the host layer. From the magnetic measurements it was found that two magnetic phase transitions occur. Above 50 K it shows paramagnetism in well agreement with Curie–Weiss law. Around 40 K it exhibits spin-glass transition and at 5 K a ferrimagnetic phase transition occurs, which is confirmed by M–H at different temperatures.

Intercalation of amino acids into layered MnPS 3: Synthesis, characterization and magnetic properties

Three bioorganic–inorganic hybrid nanocomposites based on amino acids into layered MnPS 3 have been synthesized and characterized with powder X-ray diffraction (XRD), infrared spectroscopy (IR) and elemental analysis. The expanded MnPS 3 structure as well as the characteristic IR absorption supports the successful and full intercalation of amino acids as the guests into interlayered space of MnPS 3 host. The lattice spacing expansion from XRD patterns indicates that the inserted guest is arranged in the monolayer with carbon chain parallel to the layer of MnPS 3. The magnetic measurements indicate that all three nanocomposites show paramagnetism above 50 K and obey Curie–Weiss law; however, at T c of 40 K a ferrimagnetic transition is observed. The hysteresis of magnetization ( M) versus magnetic field ( H) at 1.85 K further confirms that these intercalation compounds are low-temperature ferrimagnets.

Application of Powder X-ray Diffraction in Studying the Compaction Behavior of Bulk Pharmaceutical Powders

This study investigates the effects of crystal lattice deformation on the powder X-ray diffraction (PXRD) patterns of compressed polycrystalline specimen (compacts/tablets) made from molecular, crystalline powders. The displacement of molecules and the corresponding adjustment of interplanar distances (d-spacings) between diffracting planes of PNU-288034 and PNU-177553, which have crystal habits with a high aspect ratio favoring preferred orientation during tableting, are demonstrated by shifts in the diffracted peak positions. The direction of shift in diffracted peak positions suggests a reduction of interplanar d-spacing in the crystals of PNU-288034 and PNU-177553 following compaction. There is also a general reduction of peak intensities following compression at the different compressive loads. The lattice strain representing the reduction in d-spacing is proportional to the original d-spacing of the uncompressed sample suggesting that, as with systems that obey a simple Hooke's law relationship, the further apart the planes of atoms/molecules within the lattice are, the easier it is for them to approach each other under compressive stresses. For a third model compound comprising more equant-shaped crystals of PNU-141659, the shift in diffracted peak positions are consistent with an expansion of lattice spacing after compression. This apparent anomaly is supported by the PXRD studies of the bulk powder consisting of fractured crystals where also, the shift in peak position suggests expansion of the lattice planes. Thus the crystals of PNU-141659 may be fracturing under the compressive loads used to produce the compacts. Additional studies are underway to relate the PXRD observations with the bulk tableting properties of these model compounds.

Tensile Strain in Si Due to Expansion of Lattice Spacings in CeO2 Epitaxially Grown on Si(111)

The strain in Si, on which a single-crystalline gate oxide was epitaxially grown, was investigated by evaluating lattice spacings in and Si. In-plane X-ray diffraction measurements and observations of electron diffraction patterns by a transmission electron microscope were performed to examine the lattice spacings precisely. It was found that the lattice spacings in epitaxial isotropically expanded by ∼1%, compared with those in bulk polycrystalline The oxygen-defect-induced state was observed in the valence bandedge by X-ray photoelectron spectroscopy measurements. The decrease of the coulombic interaction in ionic oxide due to the oxygen defects may induce the expansion of the lattice spacings in It was clarified that Si at 50 nm depth from the interface was tensile strained owing to the expansion of the lattice spacings in Oxygen defects in epitaxial crystalline gate dielectrics must be controlled by taking account of Si channel properties. © 2004 The Electrochemical Society. All rights reserved.

Enhancement of Dielectric Constant due to Expansion of Lattice Spacing in CeO2 Directly Grown on Si(111)

We have investigated the reason behind the enhancement of dielectric constant (ε), which occurred in CeO2 directly grown on Si(111). ε of directly grown CeO2 is enhanced to 52, which is twice as large as the reported value. From in-plane X-ray diffraction measurements and electron diffraction pattern observations using a transmission electron microscope, it has been found that the lattice spacings in CeO2 were isotopically expanded by 0.6%, as compared with the reported values in bulk CeO2. In addition, from X-ray photoelectron spectroscopy measurements, the existence of oxygen defects in CeO2 was confirmed. The oxygen defects in CeO2 may cause the decrease in coulomb interaction in the ionic crystal, resulting in the expansion of lattice spacings. The enhancement of ion movability, due to the expansion of lattice spacings is considered as the reason behind the enhancement of ε.

Taste breaking in staggered fermions from random matrix theory

Abstract We discuss the construction of a chiral random matrix model for staggered fermions. This model includes O(a2) corrections to the continuum limit of staggered fermions and is related to the zero momentum limit of the Lee-Sharpe Lagrangian for staggered fermions. The naive construction based on a specific expansion in lattice spacing (a) of the Dirac matrix produces the term which gives the dominant contribution to the observed taste splitting in the pion masses. A more careful analysis can include extra terms which are also consistent with the symmetries of staggered fermions. Lastly I will mention possible uses of the model including studies of topology and fractional powers of the fermion determinant.

The characterization and magnetic properties of inorganic-organic hybrid nanocomposites, stilbazoliums inserted into layered FePS3

Five inorganic-organic intercalation compounds (I–V) with N-methylstilbazoliumderivatives (i–v) inserted into the interlayer space of FePS3, were synthesized,and characterized with X-ray diffraction (XRD), elemental analysis and infraredspectroscopy. The XRD results indicate that in all these intercalation compounds themolecular ring planes of the guests are almost perpendicular to the layers of thehost FePS3. From the lattice expansion of intercalates IV and V itcan be inferred that a dipolar interaction may exist between the guests in theinterlayer space of the host FePS3. Their magnetic properties were measuredwith the SQUID technique. All these intercalation compounds show similar magneticproperties. At the Neel temperature of about 80 K they exhibit the antiferromagnetictransition, although the lattice spacing and the electron-accepting ability of theguest are different. It may imply that the lattice spacing expansion and an electron-effectof the guests have not altered their antiferromagnetic property of these FePS3intercalation compounds.

Nanocomposite system of N-methylstilbazoliums intercalated into lamellar FePS 3

A new series of inorganic-organic hybrid materials, 2'-R 1 -4'-R 2 -N-methylstilbazoliums (a, R 1 = R 2 = MeO; b, R 1 = R 2 = Cl; c, R 1 = R 1 = H; d, R 1 = H, R 2 = MeO; e, R 1 = H, R 2 = Cl) intercalated into lamellar FePS 3 , were synthesized through ion-exchange process. Compared with FePS 3 (d= 6.42 A), the lattice spacing expansion (Δd) of 14.6 A for Intercalate a, 13.2 A for Intercalate b and 5.7 ∼ 6.0 A for Intercalate c, d and e indicated that the molecular ring planes of the guests are perpendicular to the layers of the host. Among them the lattice spacing of 21.02 A for Intercalate a is the largest for all FePS 3 intercalates reported. Their magnetic properties were studied, all of which exhibited the similar antiferromagnetic properties with Neel temperature at around 80 K. It seems that the lattice spacing expansion and the electron-effect of substitution group of the guest have little influence on the magnetic properties for these intercalates.

Novel inorganic-organic magnet: intercalation compound of α-aminopyridine into layered MnPS 3

A new intercalate Mn 0.80 PS 3 (α-aminoyridine) 0.40 was synthesized by the direct reaction of host MnPS 3 with α-aminopyridine in the solvent of acetonitrile. X-ray powder diffraction indicated a complete intercalation and well crystallized product. The expansion of lattice spacing is ca. 6.1 A, suggesting the orientation of pyridine ring perpendicular to the layers of the host. Infrared spectrum implied the forming of protonated α-aminopyridine. The study of magnetic property by SQUID magnetometer indicated that the material exhibits bulk spontaneous magnetization below 40 K.

Influence of substrate temperature on lattice strain field and phase transition in MeV oxygen ion implanted GaAs crystals

A detailed study of the influence of substrate temperature on the radiation-induced lattice strain field and crystalline-to-amorphous (c–a) phase transition in MeV oxygen ion implanted GaAs crystals has been made using channeling Rutherford backscattering spectroscopy, secondary ion mass spectrometry, and the x-ray rocking curve technique. A comparison has been made between the cases of room temperature (RT) and low temperature (LT) (about 100 K) implantation. A strong in situ dynamic annealing process is found in RT implantation at a moderate beam current, resulting in a uniform positive strain field in the implanted layer. LT implantation introduces a freeze-in effect which impedes the recombination and diffusion of initial radiation-created lattice damage and defects, and in turn drives more efficiently the c–a transition as well as strain saturation and relaxation. The results are interpreted with a spike damage model in which the defect production process is described in terms of the competition between defect generation by nuclear spikes and defect diffusion and recombination stimulated by electronic spikes. It is also suggested that the excess population of vacancies and their complexes is responsible for lattice spacing expansion in ion-implanted GaAs crystals.

Convergent beam electron diffraction study of lattice distortion in InGaAs/GaAs strained-layer superlattices grown by metalorganic chemical vapor deposition

The intensities of sidebands in convergent beam electron diffraction reflections from plan-view specimens of strain modulated InGaAs/GaAs superlattices are dependent on the natural lattice mismatch, the ratio of the thicknesses of the superlattice layers, the period (sum of layer thicknesses) of the superlattice, and the g vectors of the reflections. The intensities of kinematic higher-order Laue zone (HOLZ) reflections have been calculated from a simple model based on alternate contraction and expansion of lattice spacings of the superlattice layers. An accurate estimate of the In content of InGaAs can be deduced from the elastic strains in the superlattice layers so obtained.

Soft magnetic properties of Fe-N and Fe-Si-N thin films sputtered in (Ar+N/sub 2/) plasma

The soft magnetic properties of sputtered (0 approximately 3-wt%) Si-Fe alloy thin films fabricated in (Ar+N/sub 2/) plasma were investigated in connection with metallurgical structure. 2.7-wt% Si-Fe film annealed at 400 degrees C shows a high effective permeability mu /sub eff/ of about 1600 at 5 MHz. It has been observed that this film consists of alpha -Fe with a grain size of less than 150 AA and a slight expansion of lattice spacing of the