Soller Slits Research Articles

The Phase Composition of Products from Electro-Erosive Cobalto-Chrome Powders, Obtained by Additive Technologies

The main requirement for powders for additive 3d technologies is the spherical shape of the particles. Such particles are most compactly packed into a certain volume and ensure the "fluidity" of the powder composition in the supply systems of the material with minimal resistance. The wide use of the EED method for processing metal waste into powders for the purpose of their reuse and application in additive technologies is hampered by the lack in the scientific and technical literature of full-fledged information on the effect of the initial composition, regimes and media on the properties of powders and technologies of practical application. Therefore, in order to develop technologies for the reuse of electroerosive powders and to evaluate the effectiveness of their use, complex theoretical and experimental studies are required. The aim of the work was to conduct a phase analysis of additive products from electroerosive cobalt-chrome powders. The phase composition of the samples was studied by X-ray diffraction on a Rigaku Ultima IV diffractometer in Cu-Kα radiation (wavelength λ = 0.154178 nm) using Soller slits. Based on the results of the X-ray diffraction analysis of additive articles from electroerosion cobalt-chrome powders, it has been experimentally established that the main phases in the sintered samples are Co, Cr and Co3C.

Soller slits automatic focusing method for multi-element fluorescence detector

In X-ray absorption fine structure (XAFS) experiments, Soller slits are widely used as filter devices in order to improve the signal to noise ratio. Performing high accuracy manual focusing operations is a time-consuming process; therefore, this work introduces an automatic focusing method for Soller slits in multi-element fluorescence detectors. This method establishes a relation model between the fluorescence intensity distribution and the coordinates of the fluorescence excitation point. According to this relation model, the actual coordinates of the fluorescence excitation point can be deduced from the detected fluorescence intensity distribution and used in focusing operations. This method has proven to be feasible in an XAFS experiment at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facility.

Resolution function for X-ray powder diffraction in a noncoplanar measurement geometry with the detector arm having two degree of freedom

A noncoplanar measurement geometry, achieved by using a diffractometer equipped with a detector arm possessing two degrees of freedom, is a promising technique for the analysis of residual stress gradients in polycrystalline objects and for anisotropic microstructure investigations. The instrumental function for a parallel beam and a set of two orthogonal receiving Soller slits is considered in detail, and the explicit analytical expressions in terms of a convolution of functions are derived. A comparison of the calculated results with the measured profiles from a NIST SRM 660b LaB6 powder standard sample shows a good agreement.

Mathematical model of horizontal divergence contribution to the integrated intensity of single crystal diffraction in XRD analysis of materials

This paper examine a number of factors involved in the phenomena occurring into the interaction of X-rays and crystals. The mathematical modeling are the scientific way of proposal and implementation of analysis techniques based on previously models tested in laboratory. Normally, in diffraction experiments, a beam of incident X-ray radiation is simultaneously affecting both vertical divergence and horizontal divergence. To obtain more precise results after achieving structural analysis by X-ray diffraction on nanostructured materials is necessary to develop physical-mathematical model of Lorentz factor.It is well known that in difractometry, horizontal divergence effects are “filtered” by the detector slit width and goniometric assembly geometry (Bragg–Brentano). These are explained by: (i) Soller slits (slits for the slot height d is much smaller than the slot length l, d≪l) does not limit the horizontal divergence of the incident beam, but limit on the vertical one and (ii) the horizontal openings of diffracted radiation measuring device (detector) are about 0.25mm for a distance of about 35cm from the crystal detector. As a result, the horizontal divergence strongly influences the integrated intensity at high angles, when cos θ take low values.Considering the importance of horizontal divergence on the integrated intensity diffraction, the aim of this paper is to obtain a physical–mathematical model that quantify through a mathematical formula, the horizontal divergence contribution to the integrated intensity of a single crystal diffraction.

Soller slit design and characteristics

For X-ray absorption spectroscopy, either in transmission mode with concentrated samples or for dilute samples in fluorescence mode, it is advantageous to improve the signal-to-noise ratio by implementing a slit apparatus. Several investigations into the improvement of measurements when slits and filters are employed have been reported; however, these have always been for a particular design and are not transferable between dissimilar systems. A generalized approach to Soller slit design will be presented which enables a target level of noise rejection to be achieved by varying the number, size and placement of the filter and Soller slit assembly. A procedure for determining the reduction in efficiency of the Soller slits with respect to misalignment with the sample will also be discussed.

Design of an anaerobic sample chamber for fluorescence measurements compatible with the Lytle detector

A sample chamber has been developed that is compatible with the commercially available Lytle ion chamber with soller slits. The key features are (i) the sample position can be shifted vertically without changing the geometry with respect to the soller slits and ion chamber, (ii) the gas-tight structure makes it possible for experiments to work with samples that require anaerobic conditions.

High resolution short focal distance Bent Crystal Laue Analyzer for copper K edge x-ray absorption spectroscopy

We have developed a compact short focal distance Bent Crystal Laue Analyzer (BCLA) for Cu speciation studies of biological systems with specific applications to cancer biology. The system provides high energy resolution and high background rejection. The system is composed of an aluminum block serving as a log spiral bender for a 15 micron thick Silicon 111 crystal and a set of soller slits. The energy resolution of the BCLA-about 14 eV at the Cu Kα line- allows resolution of the Cu Kα(1) and CuKα(2) lines. The system is easily aligned by using a set of motorized XYZ linear stages. Two operation modes are available: incident energy scans (IES) and emission energy scans (EES). IES allows scanning of the incident energy while the BCLA system is maintained at a preselected fixed position--typically CuKα(1) line. EES is used when the incident energy is fixed and the analyzer is scanned to provide the peak profile of the emission lines of Cu.

Use of Soller slits to remove reference foil fluorescence from transmission spectra

Measurement of X-ray absorption spectroscopy (XAS) in transmission is the method of choice for strong or concentrated samples. In a typical XAS experiment above 5 keV the sample is placed between the first (I(0)) and second (I(1)) ion chambers and a standard foil is placed between the second (I(1)) and third (I(2)) ion chambers for simultaneous calibration of energy during sample analysis. However, some fluorescence from the foil may be registered in I(1), causing anomalies in the transmission signal of the sample, especially when the sample edge jump is relatively small. To remedy this, Soller slits were constructed and placed between the foil and I(1) to minimize back-fluorescence from the foil. A comparison of blank and standard samples, measured with or without Soller slits or under a worst-case scenario, demonstrates the advantages of Soller slits when analyzing weak signal samples via transmission XAS.

Stress Measurement of an Austenitic Stainless Steel Foil by Transmitted Polychromatic X-Rays

Deformation properties of austenitic stainless steel foils of 0.05 mm in thickness were evaluated by using transmitted polychromatic X-rays under monotonic tensile loading. A conventional laboratory X-ray equipment with a rotating Mo anode was adopted at a tube current of 40 mA and an acceleration voltage of 60kV. Soller slits with a divergence angle of 0.5 deg were attached on both divergent and receiving sides. By the preset time of 500s, enough diffraction intensity was obtained to determine the stress. The diffraction elastic constants were measured under monotonic loading by the cos2χ method. The diffraction energy decreased almost linearly with increasing cos2χ, and the slope of the cos2χ diagram decreased with increasing applied stress. Measured diffraction elastic constants were compared with the theoretical values calculated by the Kröner model. The experimental value obtained from a single peak with high intensity agreed well with theoretical one, and the standard deviation was enough small. The lattice strain measured during plastic deformation depended on the diffraction plane. For the single peak profile, the full width at half maximum increased with applied plastic strain. From the the diffraction-plane dependence of the lattice strain, the full width at half maximum and the diffraction intensity, deformation properties of the materials can be evaluated. Diffraction method of laboratory polychromatic X-rays is effective as a simple technique to measure multiple X-ray parameters.

In situ viscometry of high-pressure melts in the Paris–Edinburgh cell: application to liquid FeS

Knowledge of the viscosity of high-pressure melts is important in various domains of research, such as geosciences or materials science. Experimentally, the viscosity of liquids can be determined using the falling sphere technique. This method has been developed at high pressures and high temperatures at Beamline ID27 of the European Synchrotron Radiation Facility (ESRF), combining a Paris–Edinburgh cell with in situ X-ray radiography. The press is interfaced to Soller slits and imaging systems to measure high-quality diffraction patterns and high-resolution X-ray images of the sample. The viscosity of the liquid is derived from the velocity of a dense sphere falling through the pressurized melt and the Stokes law. An optimized two-circle diffractometer allows for moving the press upside down in order to perform a series of measurements on a single sample. The simultaneous collection of X-ray diffraction data on liquids offers the unique opportunity of investigating the relations between viscosity and the structure of melts. The potential of this new equipment is illustrated on the example of FeS melt viscosity and its implications for the Earth's core.

How to Dip-Coat and Spin-Coat Nanoporous Double-Gyroid Silica Films with EO19-PO43-EO19 Surfactant (Pluronic P84) and Know it Using a Powder X-ray Diffractometer

Previously, the synthesis of highly oriented pure double-gyroid nanoporous silica films has been demonstrated using evaporation-induced self-assembly (EISA) and dip-coating with a specialty triblock surfactant (PEO-PPO-alkyl) as the template. For these films, grazing-incidence small-angle X-ray scattering (GISAXS) was used to determine orientation and structure. However, GISAXS is not widely available, and we have observed significant batch-to-batch variability in the PEO-PPO-alkyl surfactants used. Here, we show for the first time: (1) synthesis of highly oriented pure double-gyroid nanoporous silica films using freely available EO(19)-PO(43)-EO(19) surfactant (Pluronic-P84) as the nanostructure-directing agent, (2) the use of spin-coating and dip-coating EISA to fabricate the double-gyroid films, and (3) the use of theta-theta X-ray diffractometers (commonly available and typically used for powder X-ray diffraction, PXRD) to identify the double-gyroid phase. Processing diagrams for P84 using dip-coating and spin-coating are shown in order to map the dependency of the nanostructure on solution composition, relative humidity, and solution aging time. In addition, an effect of the rate of evaporation during EISA is observed via dependence on the angular velocity in spin-coating. Also, through quantitative comparison of the GISAXS patterns with corresponding PXRD patterns, previously unexplained diffraction peaks in the PXRD patterns are shown to result from diffraction from crystallographic planes that are not parallel to the substrate (typically not observed in PXRD) due to the small angles involved and the nonzero acceptance angle of the PXRD Soller slits. These peaks provide a means to distinctly identify the double-gyroid phase using PXRD. The same trends relating aging-time-before-coating to the phase that forms via EISA are observed with EO(19)-PO(43)-EO(19) as was the case in previous studies using EO(17)-PO(14)-C(12). This shows the generality of use of aging time to synthesize nanoporous silica films with nonionic surfactants. Finally, a list of "tips and tricks" is provided to facilitate easy reproducible synthesis of double-gyroid nanoporous silica thin films in other laboratories.

Calculation of the instrumental function in X-ray powder diffraction

A new method for calculating the total instrumental function of a conventional Bragg–Brentano diffractometer has been developed. The method is based on an exact analytical solution, derived from diffraction optics, for the contribution of each incident ray to the intensity registered by a detector of limited size. Because an incident ray is determined by two points (one is related to the source of the X-rays and the other to the sample) the effects of the coupling of specific instrumental functions, for example, equatorial and axial divergence instrumental functions, are treated together automatically. The intensity at any arbitrary point of the total instrumental profile is calculated by integrating the intensities over two simple rectangular regions: possible point positions on the source and possible point positions on the sample. The effects of Soller slits, a monochromator and sample absorption can also be taken into account. The main difference between the proposed method and the convolutive approach (in which the line profile is synthesized by convolving the specific instrumental functions) lies in the fact that the former provides an exact solution for the total instrumental function (exact solutions for specific instrumental functions can be obtained as special cases), whereas the latter is based on the approximations for the specific instrumental functions, and their coupling effects after the convolution are unknown. Unlike the ray-tracing method, in the proposed method the diffracted rays contributing to the registered intensity are considered as combined (part of the diffracted cone) and, correspondingly, the contribution to the instrumental line profile is obtained analytically for this part of the diffracted cone and not for a diffracted unit ray as in ray-tracing simulations.

Fast and adjustable-resolution grazing-incidence x-ray liquid surface diffraction

We developed a configuration using a two-dimensional detector for grazing incidence x-ray diffraction on Langmuir monolayers and, more generally, for surface diffraction on two-dimensional powders. Compared to the classical setup using a linear detector combined with Soller slits, the acquisition time is reduced by an order of magnitude (from more than 1 h to a few minutes) using the same x-ray source (synchrotron bending magnet) with a comparable signal to noise ratio. Moreover, experimental resolution can be adjusted by varying a vertical slit (horizontal gap) and, for small values of the gap, better resolution can be achieved compared to the one obtained with the Soller slits and linear detector.

Fundamental Parameters Line Profile Fitting in Laboratory Diffractometers.

The fundamental parameters approach to line profile fitting uses physically based models to generate the line profile shapes. Fundamental parameters profile fitting (FPPF) has been used to synthesize and fit data from both parallel beam and divergent beam diffractometers. The refined parameters are determined by the diffractometer configuration. In a divergent beam diffractometer these include the angular aperture of the divergence slit, the width and axial length of the receiving slit, the angular apertures of the axial Soller slits, the length and projected width of the x-ray source, the absorption coefficient and axial length of the sample. In a parallel beam system the principal parameters are the angular aperture of the equatorial analyser/Soller slits and the angular apertures of the axial Soller slits. The presence of a monochromator in the beam path is normally accommodated by modifying the wavelength spectrum and/or by changing one or more of the axial divergence parameters. Flat analyzer crystals have been incorporated into FPPF as a Lorentzian shaped angular acceptance function. One of the intrinsic benefits of the fundamental parameters approach is its adaptability any laboratory diffractometer. Good fits can normally be obtained over the whole 20 range without refinement using the known properties of the diffractometer, such as the slit sizes and diffractometer radius, and emission profile.

X-ray diffractometric study of polycrystalline precipitates within a single crystal matrix

An x-ray study which reveals diffraction peaks from an additional polycrystalline phase in a single crystal matrix, is reported. The recording of these lines was possible due to the lowering of the diffractometer background through the use of a bent monochromator and Soller slits, as well as by rotating the single crystal sample out of Bragg condition. As an example of the use of the proposed experimental strategy, the results for the silicon single crystal, in which an additional phase in the form of silicon polycrystalline grains was created by ion implantation process, are presented.

Textures of Cu and Dilute Binary Cu(Ti) and Cu(In) Thin Films

The development of texture in thin Cu and dilute binary Cu(Ti) and Cu(In) films has been investigated as a function of annealing history. The textures are comprised of , and fiber in different proportions for the three films. Annealing strengthens the texture for all films. For the annealed films, alloying with Ti strengthens the component, whereas alloying with In weakens it compared to pure copper. Two different approaches were used to derive volume fractions of texture components, namely fiber plots and orientation distributions. For strong mono-textured films of materials such as aluminum, fiber plots are most effective. For weaker, poly-textured films such as the copper alloys studied here, orientation distributions derived from pole figures provide the most reliable basis for quantitative characterization. Introduction As dimensions of very narrow copper interconnections reach the 100 nm range, the control of microstructural features such as texture and grain size becomes increasingly important. In a recent study we addressed the impact of alloying elements on the decomposition and resistivity of a series of dilute binary Cu alloy films annealed at a constant heating rate up to 950 C [1]. In this work, we focus on the impact of isothermal annealing at 400 C on the texture of pure Cu and dilute binary Cu(Ti) and Cu(In) films. In addition to the detailed behavior of the films, we briefly discuss the advantages and disadvantages of various x-ray based methods for the analysis of the texture of Cubased films. Experiment Pure Cu and dilute binary Cu(Ti) and Cu(In) alloy films were electron beam evaporated onto thermally oxidized silicon wafers. The composition and thickness of the films are listed in Table 1. X-ray diffraction (XRD) experiments were conducted using Cu Kα radiation in a Rigaku powder diffractometer with a curved graphite monochromator. These patterns were used to give a qualitative indication of the texture in the films. For the quantitative analysis of film texture, fiber plots and pole figures were used. Pole figures and fiber plots were obtained in a Philips X’Pert Pro diffractometer, utilizing an X-ray lens and 0.27 Soller slits in the path of the incident beam and a flat graphite monochromator in the path of the diffracted beam. The fiber plots were measured in 0.1 intervals per second as is commonly done in texture studies of Al films [2], while the pole figures were determined at 5 intervals every two seconds. Three pole figures {111}, {200} and {220} were obtained for each sample. In order to ensure that the use of 5 intervals for the collection of pole figures did not affect the resolution of intensity data used for the calculation of the orientation distribution functions (ODFs), sections through the pole figures were compared with 2 Title of Publication (to be inserted by the publisher) the fiber plots. Three such sections for the annealed Cu film have been overlaid on their respective fiber plots in Fig. 1 and show no discernible difference. Table 1 Composition and thickness of the films. Sample Solute [at%] Thickness [nm] Cu(Ti) 3.0 488 Cu(In) 2.6 520 Cu 420 0 20 40 60 80 0 500

Peak profile function for synchrotron X-ray diffractometry

A formula of the instrumental function for a high-resolution synchrotron X-ray diffractometer, equipped with a flat crystal analyser and a set of Soller slits for limiting the axial divergence of the diffracted beam, has been derived. The formula incorporates the effects of (i) the axial divergence of the diffracted beam limited by the Soller slits, (ii) the Bragg angle of the flat crystal analyser, and (iii) the tilt angle defined as the deviation of the normal direction of the analyser face from the goniometer plane. The model profile function given by the convolution of a Lorentzian function with the instrumental function has been applied to fit the experimental diffraction peak profiles of standard Si powder (NIST SRM640b) measured with a high-resolution synchrotron X-ray diffractometer, MDS, on beamline BL4B2 at the Photon Factory in Tsukuba. The convolution has been calculated by applying an efficient algorithm for numerical integration. The profile function reproduces not only the experimental profiles measured with a well aligned crystal analyser, but also significantly distorted profiles arising from misalignment of the analyser, withRpvalues within 1.4%, by varying only the instrumental parameter for the tilt angle. It is suggested that further convolution with a Gaussian distribution is practically not necessary for the model instrumental function to fit the data collected with MDS. More rapid computation can be achieved by applying an analytical formula of the profile function, when the tilt angle of the crystal analyser is within about 0.2°.

Novel optics for conditioning neutron beams I: Metal arrays for collimating neutrons

We describe novel, compact optical elements for collimating and/or focusing beams of slow neutrons. These optical elements are solid composites consisting of regular stacks of alternating micro-foils analogous in action to Soller slits. They are made out of pairs of metals with suitable refractive indices for reflection and/or absorption of the radiation. The performance of these proof-in-principle collimating elements is limited only by the choice of microfoil materials and uniformity of their interfaces.

Axial Divergence in a Conventional X-ray Powder Diffractometer. II. Realization and Evaluation in a Fundamental-Parameter Profile Fitting Procedure

An accurate model for the axial divergence aberration function has been implemented within a fundamental-parameters fitting procedure for diffraction profiles from a conventional X-ray powder diffractometer. The aberration function for axial divergence is derived from the geometrical dimensions of the diffractometer in the axial plane and the angular apertures of any Soller slits in the beam path. This function is then convoluted with other instrument and specimen aberration functions to form the final profile shape. As this process only requires a modest amount of computational effort, it has been incorporated into both a fundamental-parameters profile-analysis fitting program and a Rietveld refinement program. In these programs, the refinable parameters for the axial divergence contribution to the profile shape are the axial X-ray source length, the sample length, the receiving-slit length and the aperture angles of the primary and secondary Soller slits. The procedure developed has been evaluated by fitting diffraction patterns collected using two different X-ray diffractometers and a variety of Soller slits and sample configurations to introduce varying degrees of axial divergence in the incident and diffracted beams. The reference materials used for this work included Y2O3, LaB6(SRM 660), Cr2O3(SRM 674a) and CeO2(SRM 674a). In all cases, the refined instrumental parameters defining the axial divergence were in good agreement with the directly measured values. Rietveld refinement using the present axial divergence model resulted inRwpvalues that are significantly lower than those based on currently available models for this aberration function.

Axial Divergence in a Conventional X-ray Powder Diffractometer. I. Theoretical Foundations

A general model for the axial divergence aberration function has been developed for a conventional X-ray powder diffractometer equipped with either incident-beam and/or diffracted-beam Soller slits. In this model, the axial divergence function is generated from the geometrical dimensions of the diffractometer system, which include the axial lengths of the X-ray source, sample and receiving slit as well as the angular apertures of the incident-beam and diffracted-beam Soller slits. The paper describes how the diffractometer design and the extent of the axial divergence influence the shape of the axial divergence aberration function. The model is developed in three stages starting with analytical profile shapes for a single-ray incident X-ray beam. The single-ray results are then generalized to represent a line X-ray source and a specimen with axial length. In the third stage, the effects of the Soller slits in the beam path are incorporated by considering them as angular selective filters in the incident and diffracted beams. A general discussion is presented on the axial divergence aberration function with 2θ for a range of standard instrument configurations. This work forms the basis of an accurate fundamental parameters approach to profile analysis and Rietveld refinement.