Plane Spacing Research Articles

The luminescent properties and toxicity controllability investigation of novel ZnO quantum dots with Schiff base complexes modification.

The Schiff base complexes modified ZnO quantum dots (ZnO-SBC QDs) are successfully synthesized via the reflux and chemical co-precipitation route. For control experiments, we also synthesized the ZnO QDs and amino-modified ZnO QDs (ZnO-NH2 QDs). The structures and morphologies of the samples were characterized via X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), FTIR spectroscopy (IR), Fluorescence Spectrometer (FL) and so on. The XRD pattern shows that the three types of QDs possess hexagonal wurtzite structures. The TEM investigation reveals that the as-prepared products have hexagonal morphologies. The plane fringe with 0.26 nm crystalline plane spacing of three types of quantum dots is assigned to the ZnO {002} planes via HR-TEM, which match with the lattice parameter of the hexagonal wurtzite structure of ZnO and also coincide with the data obtained by XRD. By analyzing the fluorescence emission and excitation spectra of ZnO QDs, ZnO-NH2 QDs, ZnO-SBC QDs and Schiff base complexes, we find that the ZnO-SBC QDs still have a perfect fluorescence emission which makes it interesting candidates for luminescence applications such as biochemical sensors and fluorescent labels to mark the cells and DNA. This novel ZnO-SBC QDs under UV irradiation is capable of generating reactive oxygen species by UV irradiation and may be used for the photodynamic therapy. The surface modification with Schiff base complexes makes it difficult to release Zn2+, therefore the toxicity is much more controllable.

Effect of the combination characteristics of rock structural plane on the stability of a rock-mass slope

The structural planes play an important role in rock mass slope stability. In this paper, a series of triaxial tests on the rock mass samples with different dip angles, plane numbers and plane spacing of structural surfaces were carried out to study the effect of the combination characteristics of the rock structural plane on rock mass mechanic parameters. Based on the test results and the combination characteristics of the field structural plane, the rock mechanics parameters for the spillway lock chamber slope of the Liyuan hydroelectric station were forecast. The stability of the slope was rationally evaluated based on the forecasted rock mass mechanical parameters. Finally, the safety factor was obtained based on the shear strength reduction method.

Polyurethane–Bentonite Nanocomposites: Morphology and Oxygen Permeation

ABSTRACTTo provide additional functionality to the adhesive polyurethane (PU) matrices, a solution intercalation approach was used to synthesize PU nanocomposite films with layered silicate bentonites modified with different surface ammonium ions. The oxygen permeation through the composite films was correlated to the filler fraction in the composites. The morphology in the composites was characterized using X‐ray diffraction and transmission electron microscopy. The nanocomposites were observed to have mixed morphology with varying thicknesses of filler particles. The platelets were also misaligned, and a quantitative value of 50–75% randomness was determined from finite element model predictions. The X‐ray diffraction signals also indicated that the basal plane spacing was increased to 3.5 nm in the composites irrespective of the filler type and volume fraction. The oxygen permeation in the case of Tixogel VZ decreased to 25% as compared to pure polymer at 6 wt% (2.13 vol%) filler, and an average aspect ratio of 100 was observed by the finite element permeation models. The Tixogel VP filler, on the other hand, had an excess of modification molecules on the surface and combined with the polarity mismatch (Hansen parameters) of the modification with the PU chains led to an increase in the oxygen permeation through the nanocomposite films.

Nano Ag-Deposited BaTiO3 Hybrid Particles as Fillers for Polymeric Dielectric Composites: Toward High Dielectric Constant and Suppressed Loss

Nano Ag-deposited BaTiO3 (BT-Ag) hybrid particles usable as fillers for flexible polymeric composites to obtain high dielectric constant, low conductivity, and low dielectric loss were developed. BT-Ag hybrid particles were synthesized via a seed-mediated growing process by a redox reaction between silver nitrate and ethylene glycol. Nano Ag particles with a size less than 20 nm were discretely grown on the surface of the 100 nm BaTiO3. The similar lattice spacing of the (1 1 1) planes of BT and Ag led to the hetero-epitaxial growth of Ag on the BT surface. The thickness of the coherent interface was about 3 nm. The adhesion of Ag to BT efficiently prevented the continuous contact between Ag particles in the polyvinylidene fluoride (PVDF) matrix and suppressed the formation of the conducting path in the composite. As a result, with a filler loading of 43.4 vol %, the composite exhibited a dielectric constant (Dk) value of 94.3 and dielectric loss (tan δ) of 0.06 at 1 kHz. An even higher Dk value of 160 at 1 kHz (16 times larger than that of PVDF) was obtained when the content of BT-Ag was further increased, with low conductivity (σ < 10(-5) S m(-1)) and low dielectric loss (tan δ = 0.11), demonstrating promising applications in the electronic devices.

Measurement of Residual Stresses in Ferroelectric Pb(Zr0.3Ti0.7)O3 Thin Films by X-ray Diffraction

The residual stresses in Pb(Zr0.3Ti0.7)O3 thin films were measured by the sin 2Ψ method using the normal X-ray incidence. The spacing of different planes (hkl) parallel to the film surface were converted to the spacing of a set of inclined planes (100). The angles between (100) and (hkl) were equivalent to the tilting angles of (100) from the normal of film surface. The residual stresses were extracted from the linear slope of the strain difference between the equivalent inclined direction and normal direction with respect to the sin 2Ψ. The results were in consistency with that derived from the conventional sin 2Ψ method.

Crystal orientation results in different amorphization of olivine during solar wind implantation

Crystal orientation plays an important role in mineral amorphization during solar wind implantation. To discuss these effects, ion implantation experiments were carried out to irradiate natural olivine grains by 1 × 1017 cm−2 50 keV He+. Based on the olivine grains irradiated in our experiment, residual crystal planes have been identified by reference to the crystal plane's spacing shown in diffraction images. It is found that He+ ions injected along [010] damages the olivine structure more effectively than with other orientations and that this possibly relates to the higher atomic density and the vertical impact of the flux on MO6 (where M commonly represents Fe2+ and Mg2+) octahedra chains. Crystal planes perpendicular or approximately perpendicular to [010] may be destroyed easily during the early stages of irradiation, particularly for (040). However, crystal planes, such as (041), (021), (022), (120), and (140), parallel to [100] or [001] may survive until the final stages of olivine amorphization. These different characteristics affected by crystal orientation in ion implantation might help researchers to better understand the process of solar wind weathering and in dating the exposure time of lunar and asteroidal soil grains as well as interplanetary dust particles affected by the solar wind.

Illustration of Fracture Mechanism in High Temperature for TiAl Alloys

For the shorting of fracture mechanism from the point of high temperature condition, so a new method of illustration, which is carried out under the condition of high temperature, for fracture mechanism will be adopted in this paper. And a more accuracy and more understandability result can be got by this new method. Besides, the performance of TiAl alloys can be improved by making grains refined to decrease the slip plane spacing, which can be got from the mechanics analysis.

Twinning Superlattice Formation in GaAs Nanowires

Semiconductor nanowires have proven a versatile platform for the realization of novel structures unachievable by traditional planar epitaxy techniques. Among these, the periodic arrangement of twin planes to form twinning superlattice structures has generated particular interest. Here we demonstrate twinning superlattice formation in GaAs nanowires and investigate the diameter dependence of both morphology and twin plane spacing. An approximately linear relationship is found between plane spacing and nanowire diameter, which contrasts with previous results reported for both InP and GaP. Through modeling, we relate this to both the higher twin plane surface energy of GaAs coupled with the lower supersaturation relevant to Au seeded GaAs nanowire growth. Understanding and modeling the mechanism of twinning superlattice formation in III-V nanowires not only provides fundamental insight into the growth process, but also opens the door to the possibility of tailoring twin spacing for various electronic and mechanical applications.

Persistent electrochemical pillaring of graphene ensembles

The electrochemical activation of partially reduced graphite oxide (GOpr) with a layer spacing of 4.4Å was monitored by in situ XRD. After anodic activation in 1M TEABF4 in acetonitrile (AN) the interlayer spacing of the graphene planes was increased from 4.4Å to about 13Å as indicated by a new (001) peak in the XRD pattern at about 2θ=3°. During subsequent charge discharge cycles this peak is stable and demonstrates the existence of stable pillars between the graphene layers, resulting in slit-like pores of about 1nm between the graphene layers. While the respective expansion of the activated GOpr moieties is in the order of 300%, dilatometry measurements of the electrode indicate an expansion of 40% only. After activation a stable capacitance of up to 220F/g is achieved for the activated GOpr.

Anisotropy analysis of ultra-fine grain graphite and pyrolytic carbon

This paper presents the development of an analysis technique and software program to quantify the anisotropy of pyrolytic carbon or ultra-fine grain graphite using selected area electron diffraction (SAED) patterns from a transmission electron microscope. Results serve as input to a computer program that calculates the Bacon anisotropy factor (BAF) and orientation parameter (R). This was achieved by analyzing the SAED patterns to determine the full width half maximum of the two peaks on the (0001) diffraction ring, converting the SAED data into the same format as the X-ray data and then calculating the BAF and R. The methodology of calculating the BAF and R values from the SAED patterns was confirmed by comparing the calculated values with the BAF values resulting from ellipsometry measurements on two identical isotropic pyrolytic carbon (PyC) samples and resulted in a difference of less than 0.26%, while measurements on an anisotropic turbostratic pyrolytic carbon showed almost a 40% difference which may be due to the larger planar spacing changing the extraordinary refractive index and extraordinary extinction coefficient.

Oxygen Reduction Catalyzed by Platinum Nanoparticles Supported on Graphene Quantum Dots

Nanosized graphene quantum dots were prepared by acid etching of carbon fibers and used as effective substrate supports for platinum nanoparticles which were synthesized by thermolytic reduction of platinum(II) chloride in ethylene glycol. Transmission electron microscopic measurements showed that the resulting nanocomposite (Pt/G) particles exhibited an average diameter of 2.79 ± 0.38 nm, with clearly defined lattice fringes of 0.23 nm that might be assigned to the interlayer spacing of the (111) crystal planes of fcc Pt. In addition, the Pt nanoparticles were found to be wrapped with a low-contrast halo that likely arose from the poorly crystalline graphene quantum dots. X-ray diffraction studies confirmed the composite nature of the Pt/G nanoparticles, and the average size of the crystal domains of the Pt/G nanoparticles was found to be close to the nanoparticle physical dimensions, whereas for commercial Pt/C nanoparticles the size of the crystal domains was only half that of the nanoparticle diameter...

Physico-mechanical, AC-conductivity and microstructural properties of FeCl3doped HPMC polymer films

The transition metal salt doped solid polymer electrolyte (TSPE) were prepared with HPMC as a host polymer. The virgin and doped films were prepared by solution-casting method and investigated using wide angle X-ray scattering method. Micro structural parameters like lattice strain (g%), stacking/twin faults, the average number of unit cells counted in a direction perpendicular to the Bragg's plane (hkl) spacing of (hkl) planes dhkl, crystallite size Ds, distortion width, standard deviation were determined by whole pattern powder fitting (WPPF) method, which is an extension of single order method. It is found that the crystallite size decreases with the increase in the content of FeCl3. This decrease is due to increase in localized breaking of polymer network which also accounts for the amorphous nature of the material. The filler inorganic salt FeCl3 acts as plasticizer. FTIR study also confirms and justifies the interaction between the polymer and in-organic salt in the matrix. Physical properties like mechanical stability and Ac conductivity in these films are in conformity with the X-ray results.

High CEC generation and surface modification in mica and vermiculite minerals

Montmorillonite layered silicate has been commonly used to reinforce polymer matrices. Due to its swelling in water, organic modification of the mineral surface is easily achieved which makes the surface compatible with polymers. Other minerals like mica and vermiculite though can also lead to high aspect ratio platelets in nanocomposites, but they do not swell in water owing to much stronger electrostatic forces of attraction holding their platelets together (layer charge density >0.5 eq · mol−1 in comparison with 0.25–0.5 eq · mol−1 for montmorillonite). In current study, milling, delamination and cation exchange processing of mica and vermiculite minerals has been reported to explore their potential as reinforcement materials. Wet grinding and subsequent sieving of the coarse minerals led to fine-sized particles suitable to perform chemical delamination in water. The delamination process resulted in Li-mica and Na-vermiculite with enhanced access to the interlayer cations, thus, higher CEC. Successful surface modification of the delaminated minerals with alkyl ammonium ions could be achieved which resulted in significant enhancements in their basal plane spacing. Peak degradation temperatures of 260°C were measured for C18 and 2C18 modified vermiculite, whereas 300°C and 275°C were observed respectively for C18 and 2C18 modified mica minerals which make them suitable for compounding with polymers at high temperature.

Response of Macromolecular Structure to Deformation in Tectonically Deformed Coal

AbstractThe structural evolution of tectonically deformed coals (TDC) with different deformational mechanisms and different deformational intensities are investigated in depth through X‐ray diffraction (XRD) analysis on 31 samples of different metamorphic grades (Ro, max: 0.7%–3.1%) collected from the Huaibei coalfield. The results indicated that there are different evolution characteristics between the ductile and brittle deformational coals with increasing of metamorphism and deformation. On the one hand, with the increase of metamorphism, the atomic plane spacing (d002) is decreasing at step velocity, the stacking of the BSU layer (Lc) is increasing at first and then decreasing, but the extension of the BSU layer (La) and the ratio of La/Lc are decreasing initially and then increasing. On the other hand, for the brittle deformational coal, d002 is increasing initially and then decreasing, which causes an inversion of the variation of Lc and La under the lower‐middle or higher‐middle metamorphism grade when the deformational intensity was increasing. In contrast, in the ductile deformational coals, d002 decreased initially and then increased, and the value of Lc decreased with the increase of deformational intensity. But the value of La increased under the lower‐middle metamorphism grade and increased at first and then decreased under the higher‐middle metamorphism grade. We conclude that the degradation and polycondensation of TDC macromolecular structure can be obviously impacted during the ductile deformational process, because the increase and accumulation of unit dislocation perhaps transforms the stress into strain energy. Meanwhile, the brittle deformation can transform the stress into fractional heat energy, and promote the metamorphism and degradation as well. It can be concluded that deformation is more important than metamorphism to the differential evolution of the ductile and brittle deformational coals.

Structural investigation of 2 MeV proton-irradiated fullerene nanorods

Self-assembled fullerene C60-nanorods on Si (111) substrates were irradiated by 2MeV protons with fluencies ranging from 5.0×1016 to 1.0×1017ions/cm2. Proton irradiation has induced optical band-gap changes and surface modification of the C60-nanorods making them insoluble in toluene specifically. Raman spectroscopy investigations indicate a change in the substantial Raman shift to lower values of the characteristic Ag modes of C60 after irradiation. X-rays diffraction results indicate that the fcc crystalline structure of the as-deposited nanorods has a tendency to amorphous after irradiation. High resolution transmission electron transmission microscopy confirmed such a modification in the planar spacing.

Influence of field-annealing on the microstructure, magnetic and microwave properties of electrodeposited Co0.3Fe0.7 films

Microstructure, magnetic properties and microwave characteristics of Co0.3Fe0.7 films fabricated by electro-deposition technique were investigated with post deposition field-annealing from 100 to 400°C. The crystallinity and grain size of film was enhanced with annealing temperature increment. The lattice spacing of crystallographic planes has decreased with increase in field-annealing temperature. This has induced compressive stress in field-annealed films. Coercivity and saturation magnetization values were increased with enhanced crystallinity of film. Ferromagnetic resonance was observed for as-deposited and field-annealed films. The ferromagnetic resonance frequency had shifted from 0.85 to 1.81GHz as the annealing temperature was increased from 100 to 400°C which was found to strongly correlate with the increase of saturation magnetization value.

Mechanisms for ion-irradiation-induced relaxation of stress in mosaic structured Cu thin films

In this paper, helium (He) ion irradiations with various fluences were performed on sputtered Cu thin films with a mosaic structure to evolve biaxial stress. X-ray diffraction of the θ–2θ method was used to determine the residual strains in the thin films by measuring the spacing of the crystallographic planes. The results show the in-plane biaxial tensile stress has been reduced by ion irradiation. A new proposed model is discussed to explain the ion-irradiation-induced stress release in mosaic structured Cu thin films.

Non-destructive magneto-strain analysis of YB2Cu3Oy superconducting magnets using neutron diffraction in the time-of-flight mode

In general, neutron diffraction allows a non-destructive investigation of bulk samples. In this study, a magneto-strain analysis of the trapped field in YB2Cu3Oy “YBCO” superconducting bulks was carried out at 45 K using neutron diffraction time-of-flight (TOF) method. The TAKUMI TOF neutron diffractometer offers unique advantages, including accommodation of large objectives, control of the experimental set-up using a 4-axial goniometer (XYZθ), and a positional resolution of 0.01 mm allowing an accurate sample positioning. As a result, the lattice strain in the YB2Cu3Oy material could be estimated in both radial and hoop directions by estimating the difference of plane spacing with/without the trapped magnetic field. The results indicate that the samples with a low trapped field values have smaller magnetic strain than those with a high trapped field. Further, the strain in the hoop direction is higher than that in the radial direction. The present results indicate that neutron diffraction measurements are an effective method for evaluating the bulk residual strains in a non-destructive manner.

Sub-atomic dimensional metrology: developments in the control of x-ray interferometers

Within the European Metrology Research Programme funded project NANOTRACE, the nonlinearity of the next generation of optical interferometers has been measured using x-ray interferometry. The x-ray interferometer can be regarded as a ruler or translation stage whose graduations or displacement steps are based on the lattice spacing of the crystallographic planes from which the x-rays are diffracted: in this case the graduations are every 192 pm corresponding to the spacing between the (2 2 0) planes in silicon. Precise displacement of the x-ray interferometer's monolithic translation stage in steps corresponding to discrete numbers of x-ray fringes requires servo positioning capability at the picometre level. To achieve this very fine control, a digital control system has been developed which has opened up the potential for advances in metrology using x-ray interferometry that include quadrature counting of x-ray fringes.

Invariant Deformation Element Model Interpretation to the Crystallography of Diffusional Body-Centered-Cube to Face-Centered-Cube Phase Transformations

The crystallography of body-centered-cube to face-centered cube (bcc-to-fcc) diffusion phase transformations in a duplex stainless steel and a Cu-Zn alloy, including long axis, orientation relationship (OR), habit plane (HP), and dislocation spacing, is successfully interpreted with one-step rotation from the Bain lattice relationship by applying a simplified invariant line (IL) analysis. It is proposed that the dislocation slipping direction in the matrix plays an important role in controlling the crystallography of precipitation.