Step-scan Mode Research Articles

Analysis of Trace Impurities in Lithium Carbonate.

Lithium carbonate (Li2CO3) is a critical raw material in cathode material production, a core of Li-ion battery manufacturing. The quality of this material significantly influences its market value, with impurities potentially affecting Li-ion battery performance and longevity. While the importance of impurity analysis is acknowledged by suppliers and manufacturers of battery materials, reports on elemental analysis of trace impurities in Li2CO3 salt are scarce. This study aims to establish and validate an analytical methodology for detecting and quantifying trace impurities in Li2CO3 salt. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), were employed to analyze synthetic and processed lithium salt. X-ray diffraction patterns of Li2CO3 were collected via step-scanning mode in the 5-80° 2θ range. SEM-EDX was utilized for particle morphology and quantitative impurity analysis, with samples localized on copper tape. XPS equipped with a hemispherical electron analyzer was employed to analyze the surface composition of the salt. For ICP-OES analysis, a known amount of lithium salt was subjected to acid digestion and dilution with ultrapure water. Multielemental standard solutions were prepared, including elements such as Al, Cd, Cu, Fe, Mn, Ni, Pb, Si, Zn, Ca, K, Mg, Na, and S. Results confirmed the presence of the zabuyelite phase in XRD analysis, corresponding to the natural form of lithium carbonate. SEM-EDX mapping revealed impurities of Si and Al, with low relative quantification values of 0.12% and 0.14%, respectively. XPS identified eight potential impurity elements, including S, Cr, Fe, Cl, F, Zn, Mg, and Na, alongside Li, O, and C. Regarding ICP-OES analysis, performance parameters such as linearity, limit of detection (LOD), and quantification (LOQ), variance, and recovery were evaluated for analytical validation. ICP-OES results demonstrated high linearity (>0.99), with LOD and LOQ values ranging from 0.001 to 0.800 ppm and 0.003 to 1.1 ppm, respectively, for different elements. The recovery rate exceeded 90%. In conclusion, the precision of the new ICP-OES methodology renders it suitable for identifying and characterizing Li2CO3 impurities. It can effectively complement solid-state techniques such as XRD, SEM-EDX, and XPS.

Characterization of bi-layers formed over maraging steel 300 during aging process with steam atmosphere by GIXRD and SEM

Maraging steels are martensitic steels hardened by precipitation during thermal aging, with good machining properties and high strength and corrosion resistance. It is well suited for applications which require high strength-to-weight material, being used in aerospace, aeronautics and nuclear industries. A protective and corrosion resistant oxide layer can be formed during age hardening if treated in steam atmosphere. This work aims to use grazing incidence X-ray diffraction (GIXRD) to evaluate qualitatively the thickness of the layers formed during this process. GIXRD and scanning electron microscopy (SEM) were employed to identify and order the layered structure formed on four specimens of maraging steel grade 300 with different surface finishes that were previously solution annealed twice at (950 ± 5) °C for 1 h, air-cooled, and submitted to oxidation process under positive pressure around 1.5 kPa of steam at (480 ± 5) °C for 6 h followed by forced air cooling. The diffraction patterns were measured employing CuKα radiation and parallel beam, in step scan mode, using incident angles varying from 0.2º to 4.0º and 20º < 2θ < 85º. The results revealed the formation of two layers, the innermost was formed by γ-iron (austenite – fcc) phase followed by a mixture of oxides (hematite and magnetite) on the top, regardless of surface finish, which was confirmed by the SEM analysis that also allowed the measurement of the average layer’s thickness of oxides (1.130 ± 0.094) µm and austenite (0.507 ± 0.090) µm phases, and corroborated the qualitative thicknesses analysis made from GIXRD results.

Fast estimation of the enthalpy–temperature function of Phase Change Materials

This paper presents a method for fast estimation of the enthalpy–temperature function of Phase Change Materials (PCMs). The method combines a simple experimental setup with a non-iterative, reliable mathematical algorithm that allows retrieving the enthalpy–temperature function from measurements of heat flux and temperature at a single point. Distilled water was used as reference PCM for validation purposes because its enthalpy function is known with high accuracy. Moreover, water is characterized by sharp melting/solidification processes and very high enthalpy of melting, which is challenging for the estimation method proposed. The results achieved show quite good accuracy in the determination of melting point (±0.06°C), latent heat of melting (±1.5%) and specific heats (±5−8%). To prove that the estimation method also works with PCMs undergoing progressive instead of sharp melting, a composite material made of a graphite-foam enclosing a solid–solid PCM was also tested. Finally, the potential interest of the method for identifying and diagnosing PCM degradation in thermal cycling tests was shown by testing a PCM with leakage problems. Compared to Differential Scanning Calorimeter (DSC) in step-scan mode, which is the reference method for determining the enthalpy–temperature function of a PCM, our method shows comparable accuracy while providing significant advantages, such as short testing time (less than 2 h instead of days) and low-cost experimental equipment. The proposed method could hence be of great value to accelerate PCMs development and benchmark, as well as for databases building-up.

Heat capacity and thermodynamic functions of di-,tri- and tetramethylammonium lead iodide perovskites from 289 to 473 K

The heat capacity of di-, tri- and tetramethylammonium lead iodide perovskites of general formula (CH3)xNH4–xPbI3 (where 2≤x≤4) has been determined by differential scanning calorimetry (DSC) in the temperature range 289–473 K using the step-scan mode. Standard molar values C0p(298 K) of di-, tri- and tetramethylammonium lead iodide perovskites were found to be: (285.2, 318.8 and 363.4) J K–1 mol–1, respectively. Heat capacity data have been used to evaluate the thermodynamic functions of the three (CH3)xNH4–xPbI3 perovskites (entropy and enthalpy increment). Further DSC experiments were carried out simultaneously with thermogravimetry (TG) at constant heating rate (4 K min–1) to study the thermal behavior. The occurrence of a phase transition was detected in two of the three perovskites in well-defined temperature ranges and the corresponding transition temperatures (taken as the onset temperatures of the DSC peaks) resulted to be 346.6 K and 353.5 K for (CH3)3NHPbI3 and (CH3)4NPbI3, respectively. The three powder samples were also characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses.

High-energy, high-resolution, fly-scan X-ray phase tomography

High energy X-ray phase contrast tomography is tremendously beneficial to the study of thick and dense materials with poor attenuation contrast. Recently, the X-ray speckle-based imaging technique has attracted widespread interest because multimodal contrast images can now be retrieved simultaneously using an inexpensive wavefront modulator and a less stringent experimental setup. However, it is time-consuming to perform high resolution phase tomography with the conventional step-scan mode because the accumulated time overhead severely limits the speed of data acquisition for each projection. Although phase information can be extracted from a single speckle image, the spatial resolution is deteriorated due to the use of a large correlation window to track the speckle displacement. Here we report a fast data acquisition strategy utilising a fly-scan mode for near field X-ray speckle-based phase tomography. Compared to the existing step-scan scheme, the data acquisition time can be significantly reduced by more than one order of magnitude without compromising spatial resolution. Furthermore, we have extended the proposed speckle-based fly-scan phase tomography into the previously challenging high X-ray energy region (120 keV). This development opens up opportunities for a wide range of applications where exposure time and radiation dose are critical.

An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures.

Thermal control materials are employed to adjust the temperature of a spacecraft operating in deep space. The spectral emissivity is a crucial factor in evaluating the thermal radiative properties of such materials. An apparatus, composed of a Fourier transform infrared spectrometer (FTIR), a sample cooling chamber and a mechanical modulation system was demonstrated to measure low temperature infrared spectral emissivity under vacuum. The mechanical modulation system, which includes a chopper and a lock-in amplifier, is employed to reduce the interference of background radiation during measurements. The limitation of the Fourier transform frequency on the chopper frequency can be eliminated by setting the FTIR on step-scan mode. The apparatus is separated into two parts and evacuated by different pumps. In this study, a high quality emission spectrum of a sample is measured by the apparatus. The spectral emissivity of thermal control materials are obtained in the wavelength range of 8 to 14 μm at 173 and 213 K. The combined standard uncertainty of the apparatus is 3.30% at 213 K.

Influence of Scanning Parameters on X-Ray Diffraction Peaks of Copper

The aim of this work is to study the influence of x-ray diffractometer scanning parameters on the integrated intensity and full-width at half maximum (FWHM) of copper powder x-ray diffraction peaks by using statistical analysis methods. X-ray diffraction (XRD) analysis of the copper powder was accomplished using step scan mode with step sizes of 0.03o and 0.05o 2q, and preset time changes from 0.1-3.5 s. Integrated intensity of an x-ray peak was calculated by the numerical method. FWHM was measured as the width of Pearson VII model of the x-ray peak at the half-maximum intensity. The statistical analysis methods including linear regression and statistical hypothesis test were used to analyze the correlation between the preset time and the error on integrated intensity calculation, and the FWHM of a peak on the XRD pattern. The results from statistical analysis show that increasing the preset time from 0.1 s to 3.5 s does not affect the FWHM of an x-ray peak, but it reduces the relative error in integrated intensity calculation. Moreover, using the preset time greater than 1 s will minimize the relative error in integrated intensity calculation of an x-ray peak. While step size did not affect both the relative error in integrated intensity calculation or FWHM, the smaller step size would provide more data points for better accurate model of an x-ray peak.

X‐ray Diffraction and Rietveld Refinement in Deferrified Clays for Forensic Science

Soil vestiges might provide information about a crime scene. The Rietveld method with X-ray diffraction data (RM-XRD) is a nondestructive technique that makes it possible to characterize minerals present in the soils. Soil clays from the metropolitan region of Curitiba (Brazil) were submitted to DCB treatment and analyzed using XRD with CuKα radiation in the step-scan mode (0.02° 2θ/5s). The GSAS+EXPGUI software was used for RM refinement. The RM-XRD results, together with the principal component analysis (PCA) (52.6% total variance), showed the kaolinite predominance in most analyzed samples and the highest quartz contents in "site 1." Higher anatase, and gibbsite and muscovite contents influenced discrimination, mainly in "site 3" and "site 1," respectively. These results were enough to discriminate clays of four sites and two horizons using a reduced amount of sample showing that the technique can be applied to the investigation into soil vestiges.

Structure, optical and transport measurements on bulk magnetic semiconductor In1−xMnxSe

The compounds In1−xMnxSe (x = 0.0, 0.025, 0.05, 0.1 and 0.15) have been prepared by direct fusion method. X-ray powder diffraction measurements have been performed by step scanning mode. All the prepared samples are single phase and have wurtzite hexagonal crystal structure with space group P63/mmc. The crystal structure has been refined by Rietveld method using FULLPROF program. It is found that, the unit cell volume is increases with increasing Mn content which indicates that Mn 2+ ions go to In 3+ ions in the InSe lattice. Also, from the refined values of the crystallite size, it was found that the crystallite size decreases with increasing the Mn content. The energy band gap is calculated from the optical measurements and is found to increase as the Mn content increases. The electrical conductivity and the activation energy decreases with increasing Mn concentration. The coercivities, Hc increases with increasing Mn content. The susceptibility increases with increasing Mn content (x).

Identificação qualitativa de fases de uma liga hipoeutética Al-1,5%Fe em peso tratada por refusão superficial a laser por meio de difração de raios X com ângulo de incidência rasante

RESUMO Atualmente há uma ampla investigação sobre ligas de alumínio, principalmente devido a sua larga aplicação na indústria automotiva e aeroespacial devida a características, como baixa densidade, alta condutividade térmica e elétrica, além de elevada resistência à corrosão a temperatura ambiente. Ligas de Al-Fe possuem um alto grau de modificação de sua microestrutura, no caso da utilização de um tratamento adequado, permitindo, assim, o aprimoramento de suas propriedades. Neste trabalho, a amostra estudada foi a liga Al-1,5%Fe tratada através da refusão superficial a laser (RSL) de modo a aprimorar suas características superficiais. A identificação dessa liga, com relação às fases presentes, foi realizada por meio dos difratogramas de raios X com ângulo de incidência rasante (DRXIR), em função da profundidade. Nesta técnica, o ângulo de incidência dos raios X é fixo e o detector move-se fazendo a varredura 2θ, a fim de obter difratogramas em diferentes profundidades variando-se apenas o ângulo de incidência. A análise foi realizada em escala micrométrica em duas condições de coleta de dados diferentes de DRXIR. A primeira variou-se o ângulo de incidência entre 0,5° a 6°, com intervalos de 0,5°, em modo de varredura contínua de 20º a 90°. A segunda, em ângulos de incidência 3° e 6°, em modo de varredura passo a passo de 20° a 120°, usada para melhorar a qualidade dos difratogramas e, em consequência, a melhoria da identificação de fases. Como resultado, foi realizado a caracterização microestrutural da superfície tradada pela técnica de RSL, bem como da parte transversal da camada tratada por meio de microscopia ótica (MO), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS) e por meio de DRXIR da camada tratada em função da profundidade, a identificação de fases simples, como o Al e o Fe, e metaestáveis, como o AlN, Al2,144O3,2 e o Al2O3, em uma camada entre 0,6 a 7,8 µm, como consequência da alta velocidade de resfriamento e do tratamento de RSL ter sido realizado em atmosfera não controlada e sem gás de proteção.

Quick scanning monochromator for millisecond in situ and in operando X-ray absorption spectroscopy.

The design and capabilities of a novel Quick scanning Extended X-ray Absorption Fine Structure (QEXAFS) monochromator are presented. The oscillatory movement of the crystal stage is realized by means of a unique open-loop driving scheme operating a direct drive torque motor. The entire drive mechanics are installed inside of a goniometer located on the atmospheric side of the vacuum chamber. This design allows remote adjustment of the oscillation frequency and spectral range, giving complete control of QEXAFS measurements. It also features a real step-scanning mode, which operates without a control loop to prevent induced vibrations. Equipped with Si(111) and Si(311) crystals on a single stage, it facilitates an energy range from 4.0 keV to 43 keV. Extended X-ray absorption fine structure spectra up to k = 14.4 Å(-1) have been acquired within 17 ms and X-ray absorption near edge structure spectra covering more than 200 eV within 10 ms. The achieved data quality is excellent as shown by the presented measurements.

Application of Numerical Method and Statistical Analysis in the Integrated Intensity Calculation of the Peaks from the X-Ray Diffraction (XRD) Pattern of α-Iron

The aim of this work is to analyze the error of the calculated integrated intensity of the x-ray peaks of a-iron (BCC-Fe) powder from x-ray diffraction (XRD) pattern by using the numerical method and the statistical analysis. The a-Fe powder was characterized by the x-ray diffractometer using step scan mode, step sizes 0.03o 2q and 0.05o 2q, and preset times from 0.1 to 3.5 s. The integrated intensity () of an x-ray peak and its error () were calculated using numerical method. The correlation between the relative error () and the preset time or step size were analyzed by the statistical analysis methods which are linear regression and statistical hypothesis testing. The results from the statistical analysis at significance level of 0.05 show that the relative error () correlate with x = preset time or integrated intensity by when a1 and a2 are the positive constants. From the mathematical model, for this work, the step size does not affect the relative error. However, the increasing of preset time reduces relative error on integrated intensity calculation. To minimize the error on XRD analysis, the preset time should be greater than one second. Moreover, on a XRD pattern, the lower integrated intensity peak has the higher relative error.

Restoration of terahertz continuous wave image obtained by continuous scan mode with large time constant.

Abstract-continuous scan mode offers a relatively higher data achievement rate than the step scan mode, so it is often used in continuous-wave terahertz imaging to improve the imaging efficiency. The large time constant of lock-in amplifiers also provides good noise attenuation; however, it might bring motion blur to some extent in continuous scan mode. To cope with the problem, an imaging restoration method, which identifies the motion-point spread function of the motion blur, was proposed. A modified spatial filter was used to restore the blurred image. The image quality is better than that obtained by a conventional Wiener filter evaluated by a modified no-reference motion blur metric.

MO‐PIS‐Exhibit Hall‐01: Imaging: CT Dose Optimization Technologies I

MO‐PIS‐Exhibit Hall‐01: Imaging: CT Dose Optimization Technologies I

Dependence of structural data from sinθ/λ extension in Rietveld refinement of virtually texture-free laboratory X-ray powder diffraction data

Present work analyses the effects of reducing the resolution of a data set on the structural parameters of three compounds, namely nitratine NaNO 3 , gypsum CaSO 4 · 2H 2 O, and K-alum KAl(SO 4 ) 2 · 12H 2 O, characterized by an increasing degree of structural complexity. The unexpected result is that in the case of the nearly absence of preferred orientation adequate structural information can be retrieved from data sets extending up to a minimum sinq/l values of ca . 0.4, corresponding to a 2q value of ca . 75° for CuKa radiation, at least in the case of compounds characterized by fairly moderate complexity ( ca . 25 structural parameters). Therefore, in the case of experiments collected in step-scan mode, whenever time is a limiting factor, an increase of the peak/background ratio results more advantageous than the extension of the explored reciprocal lattice.

Development of a rapid Buffer-exchange system for time-resolved ATR-FTIR spectroscopy with the step-scan mode.

Attenuated total reflectance (ATR)-FTIR spectroscopy has been widely used to probe protein structural changes under various stimuli, such as light absorption, voltage change, and ligand binding, in aqueous conditions. Time-resolved measurements require a trigger, which can be controlled electronically; therefore, light and voltage changes are suitable. Here we developed a novel, rapid buffer-exchange system for time-resolved ATR-FTIR spectroscopy to monitor the ligand- or ion-binding re-action of a protein. By using the step-scan mode (time resolution; 2.5 ms), we confirmed the completion of the buffer-exchange reaction within ∼25 ms; the process was monitored by the infrared absorption change of a nitrate band at 1,350 cm−1. We also demonstrated the anion-binding reaction of a membrane protein, Natronomonas pharaonis halorhodopsin (pHR), which binds a chloride ion in the initial anion-binding site near the retinal chromophore. The formation of chloride- or nitrate-bound pHR was confirmed by an increase of the retinal absorption band at 1,528 cm−1. It also should be noted that low sample consumption (∼1 µg of protein) makes this new method a powerful technique to understand ligand–protein and ion–protein interactions, particularly for membrane proteins.

1P221 急速緩衝液交換法による時間分解全反射赤外分光法の開発(13C. 生体膜・人工膜:興奮・チャンネル,ポスター,日本生物物理学会年会第51回(2013年度))

1P221 急速緩衝液交換法による時間分解全反射赤外分光法の開発(13C. 生体膜・人工膜:興奮・チャンネル,ポスター,日本生物物理学会年会第51回(2013年度))

Heating-Induced Phase Transition of Bupropion Hydrobromide Polymorphs

Crystal phase transition and isothermal crystallization kinetics of bupropion hydrobromide is studied by thermal analysis, X-ray powder diffractometry, and scanning electron microscopy. As well known, bupropion hydrobromide has two stable polymorphic forms, form I and form II, during the production. Here it is found that form II will convert into form I with thermal treatment. Avrami exponent n is evaluated to be around 2.0 in the range 170°C-190°C, which indicates that the phase transition is a process of one-dimensional nucleation growth. This viewpoint is also confirmed by microscope morphology study. In addition, phase-transition active energy is calculated to be 239.4 kJ/mol, which means that a high energy barrier needs to be overcome to start up the phase transition.

Fourier transform infrared spectroscopy approach for measurements of photoluminescence and electroluminescence in mid-infrared

An improved Fourier transform infrared spectroscopy approach adapting to photoluminescence and electroluminescence measurements in mid-infrared has been developed, in which diode-pumped solid-state excitation lasers were adopted for photoluminescence excitation. In this approach, three different Fourier transform infrared modes of rapid scan, double modulation, and step scan were software switchable without changing the hardware or connections. The advantages and limitations of each mode were analyzed in detail. Using this approach a group of III-V and II-VI samples from near-infrared extending to mid-infrared with photoluminescence intensities in a wider range have been characterized at room temperature to demonstrate the validity and overall performances of the system. The weaker electroluminescence of quantum cascade lasers in mid-infrared band was also surveyed at different resolutions. Results show that for samples with relatively strong photoluminescence or electroluminescence out off the background, rapid scan mode is the most preferable. For weaker photoluminescence or electroluminescence overlapped with background, double modulation is the most effective mode. To get a better signal noise ratio when weaker photoluminescence or electroluminescence signal has been observed in double modulation mode, switching to step scan mode should be an advisable option despite the long data acquiring time and limited resolution.

Trap levels in low density polyethylene doped with nanoparticles by photo-stimulated discharge

Trap levels in nanoparticle doped low density polyethylene (LDPE) are investigated by photo-stimulated discharge (PSD). The PSD spectra in MgO/LDPE and Al2O3/LDPE nanocomposites with the different mass percentages and different nanocomposites with the same mass percentage are obtained by continuous scanning mode, which can be qualitatively estimate the trap energy distribution. The trap levels in Al2O3/LDPE nanocomposite are quantitatively described by step scanning mode. The experimental results indicate that the trap levels in Al2O3/LDPE nanocomposites with the Al2O3 content of more than 0.2% and MgO/LDPE nanocomposites with the MgO content of more than 0.5% are deeper than those of the virgin LDPE. According to the relevant reports on the effect of nanoparticle doping on space charge injection, it is considered that the suppression of space charge is probably correlated with the deeper trap levels in nanocomposites.