Variation Of Lattice Spacing Research Articles

Green synthesis of graphene for targeted recovery of silver from photovoltaic waste

Atmospheric pressure microwave plasma can synthesize freestanding graphene in a few seconds at ambient conditions. Recent research has explored this method for the synthesis of graphene yet constrained by the utilization of toxic or non-renewable resources. This study aimed to substitute environmentally benign and sustainable precursors, synthesizing graphene from expired tangerine peel oil, an abundant natural source globally. The Raman spectrum of synthesized material showed a characteristic graphene-related 2D peak at microwave powers varied between 200 and 1000 W. The images of transmission electron microscopy revealed interstitial spacing of 0.34, which matched the value of X-ray diffraction calculated through Bragg's law. However, marginal variations in lattice spacing owing to the presence of oxygen functional groups were also observed. Additionally, the as-synthesized graphene deposited on a screen-printed electrode was used to selectively recover silver from spent photovoltaics. Our approach of creating a graphene-silver composite directly from waste material offers environmental benefits, resource utilization, waste reduction, and versatile applications in electrochemistry.

In Situ Synchrotron XRD Characterization of Piezoelectric Al1−xScxN Thin Films for MEMS Applications

Aluminum scandium nitride (Al1-xScxN) film has drawn considerable attention owing to its enhanced piezoelectric response for micro-electromechanical system (MEMS) applications. Understanding the fundamentals of piezoelectricity would require a precise characterization of the piezoelectric coefficient, which is also crucial for MEMS device design. In this study, we proposed an in situ method based on a synchrotron X-ray diffraction (XRD) system to characterize the longitudinal piezoelectric constant d33 of Al1-xScxN film. The measurement results quantitatively demonstrated the piezoelectric effect of Al1-xScxN films by lattice spacing variation upon applied external voltage. The as-extracted d33 had a reasonable accuracy compared with the conventional high over-tone bulk acoustic resonators (HBAR) devices and Berlincourt methods. It was also found that the substrate clamping effect, leading to underestimation of d33 from in situ synchrotron XRD measurement while overestimation using Berlincourt method, should be thoroughly corrected in the data extraction process. The d33 of AlN and Al0.9Sc0.1N obtained by synchronous XRD method were 4.76 pC/N and 7.79 pC/N, respectively, matching well with traditional HBAR and Berlincourt methods. Our findings prove the in situ synchrotron XRD measurement as an effective method for precise piezoelectric coefficient d33 characterization.

Spatial buffer-area assisted antiferroelectric-ferroelectric transition in NaNbO3

Lead-free antiferroelectric materials can be used in environmental-friendly energy applications and are receiving tremendous attention owing to their high energy-storage density, which is achieved through a phase transition between antiferroelectric and ferroelectric state. Here, by slowing down the antiferroelectric-ferroelectric transition via controllable beam irradiation in a transmission electron microscope, we demonstrate that such a transition in NaNbO3 undergoes by means of forming a buffer-area (about 40–150 nm wide) at the on-going transition front. The spatial buffer-area approximately maintains its shape during moving and are characterized to be the antiferroelectric phase but exhibits a gradual variation of lattice spacing along the [010] proceeding direction of phase transition. With help of such buffer-area, the overall stress or barrier between the two phases could be considerably reduced compared to the direct change between the two structures. Therefore, our findings provide new insights for understanding the dynamical energy-storage process in antiferroelectric materials.

Analysis of Dimensional Change in Zr-2.5%Nb CANDU Pressure Tube Material aged at 300-400°C using Neutron Diffraction

The primary boundary of the CANDU reactor consists of Zr-2.5%Nb alloy pressure tubes and SA106 alloy feeder pipes. The pressure tubes are exposed to fast neutron (E>1Mev) irradiation during reactor operation, and experience dimensional changes. The actual dimensional change in the pressure tube during in-service operation is greater than the design estimate. It is not fully understood what is responsible for the dimensional changes in the pressure tubes. In this study, to accelerate the aging effect on the pressure tube material, aging was performed at 300-400°C for up to 20,000 hours and neutron diffraction was used to track variation in lattice spacing, thereby identifying the reason for the dimensional change. The analysis result showed that α-Zr, the main phase of Zr-2.5%Nb, had little dimensional change at 350°C or lower. On the other hand, the aging treatment at 400°C resulted in anisotropic expansion in the α-Zr of the HCP crystal, of 0.02% and 0.08% in the (1010) and (0002) directions, respectively. It was confirmed that above 350oC the β-phase in the Zr-2.5%Nb alloy was decomposed to precipitate β-Nb . The driving force of the lattice expansion may be due to the diffusing out tendency of the super saturated Nb in α-Zr and due to the residual cold working effect applied during the manufacturing process. The enhancing effects of fast neutron irradiation on lattice diffusion are discussed in detail.

Effect of specimen processing for transmission electron microscopy on lattice spacing variation in Si specimens

Variation in the (220) lattice spacing of Si due to specimen processing for transmission electron microscopy (TEM) was experimentally evaluated by comparing the measured lattice spacings of crystalline specimens processed by crushing, mechanical polishing only, and combined mechanical and Ar ion polishing. Although distinct variation in the (220) lattice spacing between the Si specimens processed by crushing and by mechanical polishing only is not observed, the (220) lattice spacing of specimens prepared by combined mechanical and Ar ion polishing imply increasing tendency with increasing Ar ion beam irradiation time. Moreover, the (220) lattice spacing measured from the outermost region of the specimen edge tends to be approximately 3% to 5% larger than that measured from the inner region, irrespective of the processing method. These results demonstrate that differences in the processing conditions of Si specimens and in the measurement location of the Si lattice spacing can be major component of the measurement uncertainty in sub-nanometer metrology using TEM with magnification calibration by the Si lattice spacing. When attempting to apply the lattice spacing of Si as a reference with traceability to the International System of Units for TEM magnification calibration in sub-nanometer metrology, the results suggest that the effect of specimen processing on variation in the lattice spacing is not negligible.

Bottom-Up Assembled Photonic Crystals for Structure-Enabled Label-Free Sensing.

Photonic crystals (PhCs) display photonic stop bands (PSBs) and at the edges of these PSBs transport light with reduced velocity, enabling the PhCs to confine and manipulate incident light with enhanced light–matter interaction. Intense research has been devoted to leveraging the optical properties of PhCs for the development of optical sensors for bioassays, diagnosis, and environmental monitoring. These applications have furthermore benefited from the inherently large surface area of PhCs, giving rise to high analyte adsorption and the wide range of options for structural variations of the PhCs leading to enhanced light–matter interaction. Here, we focus on bottom-up assembled PhCs and review the significant advances that have been made in their use as label-free sensors. We describe their potential for point-of-care devices and in the review include their structural design, constituent materials, fabrication strategy, and sensing working principles. We thereby classify them according to five sensing principles: sensing of refractive index variations, sensing by lattice spacing variations, enhanced fluorescence spectroscopy, surface-enhanced Raman spectroscopy, and configuration transitions.

Multiple Anionic Transition-Metal Oxycarbide for Better Lithium Storage and Facilitated Multielectron Reactions.

As an important class of multielectron reaction materials, the applications of transition-metal oxides (TMOs) are impeded by volume expansion and poor electrochemical activity. To address these intrinsic limitations, the renewal of TMOs inspires research on incorporating an advanced interface layer with multiple anionic characteristics, which may add functionality to support properties inaccessible to a single-anion TMO electrode. Herein, a transition-metal oxycarbide (TMOC, M = Mo) with more than one anionic species was prepared as an interface layer on a corresponding oxide. A multiple anionic TMOC possesses advantages of structural stability, abundant active sites, and elevated metal cation valence states. Such merits mitigate volume changes and enhance multielectron reactions significantly. The TMOC nanocomposite has a well-maintained capacity after 1000 cycles at 2 A·g-1 and fully resumed rate performance. In situ synchrotron X-ray powder diffraction (SXRPD) analysis unveils negligible volume expansions occurring upon oxycarbide layer coupling, with lattice spacing variation less than 1% during cycling. The lithium storage mechanism is further inspected by combined analysis of kinetics, SXRPD, and first-principles calculations. Superior to TMO, multielectron reactions of the TMOC electrode have been boosted due to easier rupture of the metal-oxygen bond. Such improvements underscore the importance of incorporating an oxycarbide configuration as a strategy to expand applications of TMOs.

Anomalous Wavelength Scaling of Tightly Coupled Terahertz Metasurfaces.

We theoretically and experimentally demonstrate the drastic changes in the wavelength scaling of tightly coupled metasurfaces caused by deep subwavelength variations in the distance between the unit resonators but no change in the length scale of the units themselves. This coupling-dependent wavelength scaling is elucidated by our model metasurfaces of ring resonators arranged with deep subwavelength lattice spacing g, and we show that narrower g results in rapider changes in wavelength scaling. Also, by using terahertz time-domain spectroscopy, we experimentally observed a significant shift of the spectral response arising from very small variations in lattice spacing, confirming our theoretical predictions.

Structural coloration of chitosan-cationized cotton fabric using photonic crystals

In this work, poly (styrene-methyl methacrylate-acrylic acid) P(St-MMA-AA) composite nanospheres were deposited onto chitosan-cationized woven cotton fabrics followed by a second layer of chitosan. The deposited photonic crystals (PCs) on the fabrics were evaluated for coating efficiency and resistance, chemical analysis and color variation by optical and SEM microscopy, ATR-FTIR, diffuse reflectance spectroscopy and washing fastness. Chitosan deposition on cotton fabric provided cationic groups on the fiber surface promoting electrostatic interaction with photonic crystals. SEM images of the washed samples indicate that the PCs are firmly coated on the cotton surface only in the chitosan treated sample. The photonic nanospheres show an average diameter of 280 nm and display a face-centered cubic closepacking structure with an average thickness of 10 μm. A further chitosan post-treatment enhances color yield of the samples due to the chitosan transparent covering layer that induce bright reflections where the angles of incidence and reflection are the same. After washing, no photonic crystal can be detected on control fabric surface. However, the sample that received a chitosan post-treatment showed a good washing fastness maintaining a reasonable degree of iridescence. Chitosan fills the spaces between the polymer spheres in the matrix stabilizing the photonic structure. Sizeable variations in lattice spacing will allow color variations using more flexible non-close-packed photonic crystal arrays in chitosan hydrogels matrices.

Experimental verification of the hydrogen concentration around a crack tip using spot X-ray diffraction

We employed X-ray diffraction using collimated X-rays to quantitatively evaluate the local hydrogen concentration behavior in metals. Hydrogen concentrating around a crack tip significantly accelerates crack propagation, i.e., hydrogen embrittlement. In order to clarify the mechanism leading to this, the local hydrogen concentration behavior, i.e., at a crack tip, was evaluated by numerical analysis and experimental measurements. Although thermal desorption analysis can be used to evaluate the total hydrogen content in metals, it cannot be applied to local areas. Microprint methods, which use chemical reactions between hydrogen and coated elements cannot quantitatively evaluate the hydrogen content. The present study takes account of hydrogen-induced strain, and X-ray diffraction in a confined area was employed to detect variations in lattice spacing before and after hydrogen charging. Using X-ray diffraction applied to a small area, we demonstrate that the hydrogen concentrates in the vicinity of the crack, i.e., at the elastic–plastic boundary.

Zinc oxysulfide ternary alloy nanocrystals: A bandgap modulated photocatalyst

Herein, we report a green economic route for the synthesis of a series of Zinc Oxysulfide (ZOS) (ZnO1−xSx; 0 ≤ x ≥ 1; x = Sulfur) alloys nanoparticles. The crystallographic features of ZnO, ZOS, and ZnS confirmed by X-Ray Diffraction and validated by Transmission Electron Microscopy reveal the variation of lattice spacing in binary and ternary compositions with homogenous elemental distribution. The photocatalytic analysis of ZOS (0.4) is performed and compared with Degussa P25 to ascertain its photocatalytic activity against methyl orange under irradiation of 365 nm UV-Vis light. A bandgap of 2.7 eV for ZOS (0.4) aptly establishes its prospects for sunlight driven photocatalysis.

Rapid growth of large, defect-free colloidal crystals

We demonstrate controlled growth of face-centered cubic (FCC), monodisperse hard-sphere colloidal crystals by centrifugation at up to 3000g onto FCC (100) templates. Such rapid deposition rates often result in an amorphous sediment. Surprisingly, however, growth onto (100) templates results only in single crystals with few or no extended defects. By contrast, deposition onto flat, (111), or (110) templates causes rapid disordering to an amorphous sediment if the dimensionless flux (particle volume fraction × Peclet number) exceeds a critical value. This crystalline-to-amorphous crossover results from the degeneracy of possible stacking positions for these orientations. No such degeneracy exists for growth onto (100). After growth, extended defects can nucleate and grow only if the crystal exceeds a critical thickness that depends on the lattice misfit with the template spacing. The experimental observations of the density of misfit dislocations are accounted for by the Frank–van der Merwe theory, adapted for the depth-dependent variation of lattice spacing and elastic constants that results from the gravitational pressure.

Structural and thermal properties of polysulfone-ZnO nanocomposites

Polymer nanocomposite thin film of polysulfone with different concentration of ZnO was prepared by solution grown technique. This paper presents a study on the structural and thermal properties of ZnO filled Polysulfone (PSF) nanocomposites. The structural morphology of the resulting nanocomposites was investigated by X-ray diffraction (XRD), Scanning electron microcopy (SEM), and Atomic force microscopy (AFM). Thermal properties of PSF nanocomposites samples were investigated by Differential thermal analysis, Thermal gravimetric, and Differential thermal gravimetric. Structural result shows that the ZnO nanofiller with different mass% in polymer matrix cause the significant variation of lattice spacing, crystallite size, and percentage crystallinity. XRD result shows that the amorphous behavior of PSF (Pristine) is increasing with incorporation of ZnO nanoparticle in PSF matrix. The SEM and AFM images show the change in structural morphology of PSF due to incorporation of ZnO nanoparticles. The thermal analysis result shows that the significant thermal degradation of polysulfone nanocomposites due to catalytic behavior of ZnO nanoparticles.

Ignoring Your Neighbors: Moment Correlations Dominated by Indirect or Distant Interactions in an Ordered Nanomagnet Array

We have studied the moment correlations within triangular lattice arrays of single-domain coaligned nanoscale ferromagnetic islands. Independent variation of lattice spacing along and perpendicular to the island axis tunes the magnetostatic interactions between islands through a broad range of relative strengths. For certain lattice parameters, the sign of the correlations between near-neighbor island moments is opposite to that favored by the pairwise interaction. This finding, supported by analysis of the total correlation in terms of direct and convoluted indirect contributions across multiple pairwise interactions, indicates that indirect interactions and/or those mediated by further neighbors can be tuned to be dominant, with implications for the wide range of systems composed of interacting nanomagnets.

Facile fabrication of mechanochromic-responsive colloidal crystal films

This paper presents a simple approach to fabricate a reversible mechanochromic-responsive crystal film based on the room-temperature film-formation of monodisperse polymer latex by the aid of nanosilica particles. In this approach, when the "soft" colloidal polymer spheres were blended with colloidal silica particles and then cast on a substrate, followed by drying at room temperature for self-assembly, an elastic crystal film was directly obtained. This crystal film has not only reversible and repeatable mechanochromic-responsive property, but also tunable color and peak position covering almost entire visible spectral region, depending upon the sizes of polymer spheres and strains. This optical response is attributed to the variation of lattice spacing during deformation.

Residual Stresses in Inertia-Friction-Welded Dissimilar High-Strength Steels

The welding of dissimilar alloys is seen increasingly as a way forward to improve efficiencies in modern aeroengines, because it allows one to tailor varying material property demands across a component. Dissimilar inertia friction welding (IFW) of two high-strength steels, Aermet 100 and S/CMV, has been identified as a possible joint for rotating gas turbine components and the resulting welds are investigated in this article. In order to understand the impact of the welding process and predict the life expectancy of such structures, a detailed understanding of the residual stress fields present in the welded component is needed. By combining energy-dispersive synchrotron X-ray diffraction (EDSXRD) and neutron diffraction, it has been possible to map the variations in lattice spacing of the ferritic phase on both sides of two tubular Aermet 100-S/CMV inertia friction welds (as-welded and postweld heat-treated condition) with a wall thickness of 37 mm. Laboratory-based XRD measurements were required to take into account the variation in the strain-free d-spacing across the weld region. It was found that, in the heat-affected zone (HAZ) slightly away from the weld line, residual stress fields showed tensile stresses increasing most dramatically in the hoop direction toward the weld line. Closer to the weld line, in the plastically affected zone, a sharp drop in the residual stresses was observed on both sides, although more dramatically in the S/CMV. In addition to residual stress mapping, synchrotron XRD measurements were carried out to map microstructural changes in thin slices cut from the welds. By studying the diffraction peak asymmetry of the 200-α diffraction peak, it was possible to demonstrate that a martensitic phase transformation in the S/CMV is responsible for the significant stress reduction close to the weld line. The postweld heat treatment (PWHT) chosen to avoid any overaging of the Aermet 100 and to temper the S/CMV martensite resulted in little stress relief on the S/CMV side of the weld.

Length-dependent Ca2+ activation in cardiac muscle: some remaining questions

The steep relationship between systolic force and end diastolic volume in cardiac muscle (Frank-Starling relation) is, to a large extent, based on length-dependent changes in myofilament Ca(2+) sensitivity. How sarcomere length modulates Ca(2+) sensitivity is still a topic of active investigation. Two general themes have emerged in recent years. On the one hand, there is a large body of evidence indicating that length-dependent changes in lattice spacing determine changes in Ca(2+) sensitivity for a given set of conditions. A model has been put forward in which the number of strong-binding cross-bridges that are formed is directly related to the proximity of the myosin heads to binding sites on actin. On the other hand, there is also a body of evidence suggesting that lattice spacing and Ca(2+) sensitivity are not tightly linked and that there is a length-sensing element in the sarcomere, which can modulate actin-myosin interactions independent of changes in lattice spacing. In this review, we examine the evidence that has been cited in support of these viewpoints. Much recent progress has been based on the combination of mechanical measurements with X-ray diffraction analysis of lattice spacing and cross-bridge interaction with actin. Compelling evidence indicates that the relationship between sarcomere length and lattice spacing is influenced by the elastic properties of titin and that changes in lattice spacing directly modulate cross-bridge interactions with thin filaments. However, there is also evidence that the precise relationship between Ca(2+) sensitivity and lattice spacing can be altered by changes in protein isoform expression, protein phosphorylation, modifiers of cross-bridge kinetics, and changes in titin compliance. Hence although there is no unique relationship between Ca(2+) sensitivity and lattice spacing the evidence strongly suggests that under any given set of physiological circumstances variation in lattice spacing is the major determinant of length-dependent changes in Ca(2+) sensitivity.

Ferroelastic phase transitions and domain structures in powders

Abstract Powder patterns of samples resulting from ferroelastic phase transitions generally show typical line profiles: asymmetry into the direction of the position of the corresponding hypothetical high symmetry reflection and strongly anisotropic line broadening. An approximate model is presented that describes the characteristic distribution of individual line widths based on the variation of lattice spacings within the domain walls. The variation with temperature is governed by the competition of decreasing spontaneous strain and increasing wall widths and/or wall densities. It is argued that conventional Rietveld refinements can easily lead to erroneous results and a simplified method is proposed to approximate the actual line profiles via the introduction of a second phase with anisotropic strain broadening to take into account the scattering fom the domain walls.

Strength and equation of state of boron suboxide from radial x-ray diffraction in a diamond cell under nonhydrostatic compression

Using radial x-ray diffraction techniques together with lattice strain theory, the behavior of boron suboxide $({\mathrm{B}}_{6}\mathrm{O})$ was investigated under nonhydrostatic compression to $65.3\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ in a diamond-anvil cell. The apparent bulk modulus derived from nonhydrostatic compression data varies from $363\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}124\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ depending on the orientation of the diffraction planes with respect to the loading axis. Measurement of the variation of lattice spacing with angle, $\ensuremath{\psi}$, from the loading axis allows the $d$ spacings corresponding to hydrostatic compression to be obtained. The hydrostatic $d$ spacing obtained from a linear fitting to data at 0\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} is consistent with direct measurements at the appropriate angle $(\ensuremath{\psi}=54.7\ifmmode^\circ\else\textdegree\fi{})$ to within 0.5%, which suggests that even two measurements ($\ensuremath{\psi}=0\ifmmode^\circ\else\textdegree\fi{}$ and 90\ifmmode^\circ\else\textdegree\fi{}) are sufficient for accurate hydrostatic equation of state determination. The hydrostatic compression data yield a bulk modulus ${K}_{0}=270\ifmmode\pm\else\textpm\fi{}12\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and its pressure derivative ${K}_{0}^{\ensuremath{'}}=1.8\ifmmode\pm\else\textpm\fi{}0.3$. The ratio of differential stress to shear modulus ranges from 0.021 to 0.095 at pressures of $9.3--65.3\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$. Together with estimates of the high-pressure shear modulus, a lower bound to the yield strength is $26--30\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ at the highest pressure. The yield strength of ${\mathrm{B}}_{6}\mathrm{O}$ is about a factor of 2 larger than for other strong solids such as ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$. The ratio of yield stress to shear modulus derived from lattice strain theory is also consistent with the result obtained by the analysis of x-ray peak width. This ratio might be a good qualitative indicator of hardness as it reflects the contributions of both plastic and elastic deformation.

Diffusion behavior in spin valves studied by high resolution transmission electron microscopy and nanobeam technique

x4282 NiMn/NiFe/Co/Cu/Co/NiFe/seed layer and NiFe/CoFe/Cu/CoFe/Ru/CoFe/NiFe/NiMn/seed layer structures have been investigated using high resolution transmission electron microscopy (HRTEM) coupled with nanobeam energy dispersive X-ray (EDX) and electron energy loss spectroscopy (EELS). An accumulated sum technique was applied to analyse the lattice spacing variation across the ultra-thin film from HRTEM micrographs. A Wiener filter was used to remove the electron beam broadening effect from nanobeam EDX data to improve the spatial resolution of composition profiles. A combination of these two techniques (lattice variation measurement and the deconvolution of nanobeam EDX) allows any interdiffusion effects between the ultra-thin films in the spin-valve devices to be revealed. The compositional analysis shows that diffusion of Mn and Ni into the Cu/Co bilayer is only observed in the Co/Cu/Co sample. This result indicates that the Ru layer in the CoFe/Cu/CoFe sample might not only act as a spacer of the synthetic antiferromagnet but also behaves as a good diffusion barrier for Ni and Mn elements in the spin valve structure. The diffusion coefficients of constituent elements are simply determined by using the Matano–Boltzmann method from the deconvoluted compositional profiles. Diffusion of Cu in Co and Ni in Co is primarily by the grain boundary mechanism. In the CoFe/Cu/CoFe/Ru/CoFe sample, diffusivity of Cu and Ni is smaller than that in the Co/Cu/Co sample.