Energy Dispersive X-ray Diffraction Data Research Articles

HpMCA: a Python-based graphical program for energy-dispersive X-ray diffraction data collection and analysis

ABSTRACT Energy-dispersive X-ray diffraction (EDXD) at synchrotron beamlines is commonly used for the study of material properties under high pressure and/or high temperature. Experimenters typically rely on the availability of robust data collection and analysis at a beamline, but this has become increasingly difficult, especially with the introduction of multi-element detectors that generate complex, multi-dimensional data sets. These data sets have energy resolution, and they can also be resolved in relation to sample position, diffraction angle, or different external stimuli. We report a new Python-based graphical program, hpMCA, for EDXD data collection and analysis that streamlines the experimental process for the beamline users. The program features a user-friendly interface, capability for online viewing and analyzing data from multi-element energy-dispersive detectors, and includes features useful for working with samples under high pressure and/or high temperature, such as crystal phase identification, real-time unit cell lattice refinement, and pressure determination based on an equation of state.

Stress Formation During In - Ga Interdiffusion in Thin-Film CuIn1−xGaxSe2 Absorber Layers Leads to Stable Ga Gradients

To optimize the opto-electronic properties of compound semiconductors, a detailed understanding and control of compositional gradients forming during their synthesis is crucial. A common fabrication process for $\mathrm{Cu}(\mathrm{In},\mathrm{Ga}){\mathrm{Se}}_{2}$ (CIGS) thin-film solar cells uses annealing at high temperatures, which---contrary to what could be expected from simple Fickian diffusion---results in the formation of steep and stable $\mathrm{Ga}$ gradients, deviating from the optimal $\mathrm{Ga}$ profile for high-efficiency CIGS absorbers. Here, we show that the formation of elastic stresses inside the material during the interdiffusion can have a profound effect on the final $\mathrm{Ga}$ distribution, resulting in persistent $\mathrm{Ga}$ gradients inside CIGS absorber layers. A comparison of numerical diffusion and stress-formation calculations with real-time synchroton-based energy-dispersive x-ray diffraction data acquired in-situ during selenization of CIGS thin films demonstrates that the model can reproduce the stagnation of $\mathrm{In}$-$\mathrm{Ga}$ interdiffusion. We discuss that a detailed understanding of the interplay between stress and diffusion processes in thin films may open alternative fabrication strategies for generating desired stable compositional gradients to improve the opto-electronic properties of compound semiconductors, such as chalcopyrite, kesterite, and perovskite solar cell absorbers for solar cells.

Discharge Reactions of γ-MnO2 and Mo6S8 Tracked in the Electrode Bulk of Sealed Devices By Energy Dispersive X-Ray Diffraction (EDXRD)

Energy dispersive X-ray diffraction (EDXRD) from a high energy source allows the evolution of materials to be tracked from deep within large specimens, due to (a) the use of highly penetrating X-rays and (b) the ability to define a well-controlled diffraction gauge volume in space.1,2 This non-destructive characterization tool lends itself to the study of batteries, whose electrodes are generally composites of compressed particles, with electrolyte filling the pore space, and a sealed containment surrounding the cell designed to be as compact as possible. The fundamental electrochemistry of the active material can be known from laboratory experiments, but reaction inhomogeneity that is a consequence of the system itself is best observed in an in situ fashion without disassembly, or in an operando fashion within the battery as it cycles. EDXRD allows tomographic-like observation of the bulk interior of electrodes and critical locations such as the electrode-separator interfaces.3,4 This talk will illustrate the technique for understanding complex electrochemical reactions in three diverse systems: (1) proton insertion into γ-MnO2 in alkaline electrolyte, (2) Al3+ intercalation into Mo6S8 chevrel in chloroaluminate electrolyte, and (3) Zn2+ intercalation into Mo6S8 in aqueous ZnSO4. Deeply cycling MnO2 (617 mAh/g-MnO2) has the potential to provide battery storage of high safety, high energy density, and low cost, for applications such as intermittent renewable generation backup at the scale of the power grid.5 Figure 1a shows the γ-MnO2 discharge curve, in which reduction to one electron equivalent per Mn (x = 1) proceeds through proton insertion. Reaction beyond this point involves new phase formation at relatively constant potential. Operando EDXRD data in Figure 1b reveals that the nominal discharge product Mn(OH)2 was found only in a relatively small region clustered at the Ni current collector, while a propagating front of Mn3O4 traversed the electrode (panel iii). Figure 1c correlates the spatial locations of the various crystalline phases with the potential data in 1a. This shows that the final potential plateau at x = 1.8 corresponded to sudden Mn(OH)2 formation throughout the electrode, a phenomenon not previously reported.6 Dopant strategies to provoke earlier Mn(OH)2 formation and suppress Mn3O4 hold the key to MnO2 rechargeability.7 EDXRD is also useful in situations when electrode discharge products are prone to damage or alteration by cell disassembly, casting doubt on material structures observed by ex situ analysis. The chevrel phase Mo6S8 has been shown to intercalate divalent and trivalent ions, making it an important material of study. It is known that two second order phase transitions are expected during intercalation of a guest ion A into the host chevrel: Mo6S8 → AMo6S8 → A2Mo6S8.8 However, a recent ex situ study of Zn2+ intercalation suggested that conversion to Zn2Mo6S8 may be incomplete.9 We demonstrate this was a consequence of material oxidation during cell disassembly, and that when observed by EDXRD conversion to Zn2Mo6S8 is complete. The corresponding Al3+ intercalation will be compared to show there is only one phase transition in this case. References M. Croft, V. Shukla, E. K. Akdogan, N. Jisrawi, Z. Zhong, R. Sadangi, A. Ignatov, L. Balarinni, K. Horvath and T. Tsakalakos, J Appl Phys, 105 (2009).M. Croft, V. Shukla, N. M. Jisrawi, Z. Zhong, R. K. Sadangi, R. L. Holtz, P. S. Pao, K. Horvath, K. Sadananda, A. Ignatov, J. Skaritka and T. Tsakalakos, Int J Fatigue, 31, 1669 (2009).E. S. Takeuchi, A. C. Marschilok, K. J. Takeuchi, A. Ignatov, Z. Zhong and M. Croft, Energ Environ Sci, 6, 1465 (2013).J. W. Gallaway, C. K. Erdonmez, Z. Zhong, M. Croft, L. A. Sviridov, T. Z. Sholklapper, D. E. Turney, S. Banerjee and D. A. Steingart, Journal of Materials Chemistry A, 2, 2757 (2014).N. D. Ingale, J. W. Gallaway, M. Nyce, A. Couzis and S. Banerjee, J Power Sources, 276, 7 (2015).J. W. Gallaway, G. G. Yadav, D. E. Turney, M. Nyce, J. Huang, Y.-c. K. Chen-Wiegart, G. Williams, J. Thieme, J. S. Okasinski and X. Wei, J Electrochem Soc, 165, A2935 (2018).G. G. Yadav, J. W. Gallaway, D. E. Turney, M. Nyce, J. C. Huang, X. Wei and S. Banerjee, Nature Communications, 8 (2017).E. Levi, E. Lancry, A. Mitelman, D. Aurbach, G. Ceder, D. Morgan and O. Isnard, Chem Mater, 18, 5492 (2006).M. S. Chae, J. W. Heo, S.-C. Lim and S.-T. Hong, Inorg Chem, 55, 3294 (2016). Figure 1

Multivariate calibration of energy-dispersive X-ray diffraction data for predicting the composition of pharmaceutical tablets in packaging

A system using energy-dispersive X-ray diffraction (EDXRD) has been developed and tested using multivariate calibration for the quantitative analysis of tablet-form mixtures of common pharmaceutical ingredients. A principal advantage of EDXRD over the more traditional and common angular dispersive X-ray diffraction technique (ADXRD) is the potential of EDXRD to analyse tablets within their packaging, due to the higher energy X-rays used.In the experiment, a series of caffeine, paracetamol and microcrystalline cellulose mixtures were prepared and pressed into tablets. EDXRD profiles were recorded on each sample and a principal component analysis (PCA) was carried out in both unpackaged and packaged scenarios. In both cases the first two principal components explained >98% of the between-sample variance. The PCA projected the sample profiles into two dimensional principal component space in close accordance to their ternary mixture design, demonstrating the discriminating potential of the EDXRD system.A partial least squares regression (PLSR) model was built with the samples and was validated using leave-one-out cross-validation. Low prediction errors of between 2% and 4% for both unpackaged and packaged tablets were obtained for all three chemical compounds. The prediction capability through packaging demonstrates a truly non-destructive method for quantifying tablet composition and demonstrates good potential for EDXRD to be applied in the field of counterfeit medicine screening and pharmaceutical quality control.

Multivariate analysis of energy dispersive X-ray diffraction data for the detection of illicit drugs in border control

A system using energy dispersive X-ray diffraction has been tested to detect the presence of illicit drugs concealed within parcels typical of those which are imported into the UK via postal and courier services. The system was used to record diffraction data from calibration samples of diamorphine (heroin) and common cutting agents and a partial least squares regression model was established between diamorphine concentration and diffraction spectra. Parcels containing various crystalline and amorphous materials, including diamorphine, were then scanned to obtain multiple localised diffraction spectra and to form a hyperspectral image. The calibration model was used for the prediction of diamorphine concentration throughout the volume of parcels and enabled the presence and location of diamorphine to be determined from the visual inspection of concentration maps. This research demonstrates for the first time the potential of an EDXRD system to generate continuous hyperspectral images of real parcels from volume scanning in security applications and introduces the opportunity to explore hyperspectral image analysis in chemical and material identification. However, more work must be done to make the system ready for implementation in border control operations by bringing down the procedure time to operational requirements and by proving the system’s portability.

Anode Characterization in Zinc-Manganese Dioxide AA Alkaline Batteries Using Electrochemical-Acoustic Time-of-Flight Analysis

Using an ultrasonic flaw detector, electrochemical-acoustic time of flight (EAToF) experiments are performed on commercially available alkaline Zn/MnO2 LR6 (AA) batteries during discharge. The EAToF data are compared to in situ energy-dispersive X-ray diffraction (EDXRD) data and scanning electron microscope (SEM) images taken post mortem. Changes in the acoustic waveforms from EAToF measurements are shown to correlate with dehydration of the Zn gel anode and formation of ZnO, as shown by peak evolution in the EDXRD data and morphology analysis using SEM. We show that the physical transitions during discharge change the transmission of an ultrasonic pulse, and that ultrasonic time-of-flight analysis can be used to determine differences between brands of alkaline AA cells.

Interrogation of Alkaline AA Batteries Using in Operando Electrochemical ­Acoustic Time-of­-Flight Analysis and in Operando energy Dispersive X-Ray Diffraction

Recently, in operando Electrochemical ­Acoustic Time-of­-Flight (EAToF) analysis has been shown to provide information about the state of charge (SoC) and state of health (SoH) of a number of battery geometries and chemistries using ultrasonic interrogation of the density and modulus shifts that occur during charge and discharge. The technique has thus far offered a general understanding of these batteries, but has not been used for in depth analysis of individual battery chemistries. In this work, we performed EAToF measurements on commercially available alkaline Zn/MnO2 AA batteries of a number of different brands under discharge and charge conditions. The data from this method were compared to in situ energy-dispersive x-ray diffraction (EDXRD) data from comparable alkaline AA batteries. Changes in the waveforms in the ultrasonic time-of-flight measurements were shown to correlate with phase transitions in the MnO2 cathode and densification and dehydration of the Zn anode, as shown by peak evolution in the EDXRD data. The mechanisms by which the phase and morphology transitions can change the transmission and reflection of an ultrasonic pulse and the utility of EAToF analysis in determining material differences between different brands of alkaline cells are discussed.

Conformational isomerisms and nano-aggregation in substituted alkylammonium nitrates ionic liquids: An x-ray and computational study of 2-methoxyethylammonium nitrate

In this study, we discuss, using molecular dynamics simulations and energy-dispersive x-ray diffraction data, how a conformational isomerism can dramatically alter the nanosegregation phenomena that take place in a prototypical ionic liquid. The diffraction patterns of liquid 2-methoxyethylammonium nitrate are compared with the results from molecular dynamics simulations. The simulations conditions and force field parameters have been varied producing different charge models and different populations of conformers of the cation. We show that, while the short range structure is relatively unchanged in the models, the long range aggregation phenomena deemed responsible for the appearance of low Q peaks in the X-ray patterns strongly depend on the choice of the charge model. In the title compound, the best agreement with the experiment, where no low Q peaks appear, occurs if the point charges are calculated using the gauche conformation of the cation, which is characterized by an intramolecular hydrogen bond between ammonium and ether groups.

The P–V–T equation of state of CaPtO3 post-perovskite

Orthorhombic post-perovskite CaPtO3 is isostructural with post-perovskite MgSiO3, a deep-Earth phase stable only above 100 GPa. Energy-dispersive X-ray diffraction data (to 9.4 GPa and 1,024 K) for CaPtO3 have been combined with published isothermal and isobaric measurements to determine its P–V–T equation of state (EoS). A third-order Birch–Murnaghan EoS was used, with the volumetric thermal expansion coefficient (at atmospheric pressure) represented by α(T) = α0 + α1(T). The fitted parameters had values: isothermal incompressibility, \( K_{{T_{0} }} \) = 168.4(3) GPa; \( K_{{T_{0} }}^{\prime } \) = 4.48(3) (both at 298 K); \( \partial K_{{T_{0} }} /\partial T \) = −0.032(3) GPa K−1; α0 = 2.32(2) × 10−5 K−1; α1 = 5.7(4) × 10−9 K−2. The volumetric isothermal Anderson–Gruneisen parameter, δT, is 7.6(7) at 298 K. \( \partial K_{{T_{0} }} /\partial T \) for CaPtO3 is similar to that recently reported for CaIrO3, differing significantly from values found at high pressure for MgSiO3 post-perovskite (−0.0085(11) to −0.024 GPa K−1). We also report axialP–V–T EoS of similar form, the first for any post-perovskite. Fitted to the cubes of the axes, these gave \( \partial K_{{aT_{0} }} /\partial T \) = −0.038(4) GPa K−1; \( \partial K_{{bT_{0} }} /\partial T \) = −0.021(2) GPa K−1; \( \partial K_{{cT_{0} }} /\partial T \) = −0.026(5) GPa K−1, with δT = 8.9(9), 7.4(7) and 4.6(9) for a, b and c, respectively. Although \( K_{{T_{0} }} \) is lowest for the b-axis, its incompressibility is the least temperature dependent.

Diffraction peaks restoration and extraction in energy dispersive X-ray diffraction

Abstract This paper proposes a method to restore energy dispersive X-ray diffraction (EDXRD) spectra and to extract diffraction peaks. It follows a maximum a posteriori approach using a physical model of the formation of the EDXRD data to remove blur caused by both the detector and the coarse angular resolution of X-ray tube based EDXRD setup. It separates peaks due to the diffraction by crystalline material from a continuous background. Tested on real data (graphite and NaCl), our algorithm achieved to detect diffraction peaks with a good precision (about 1 keV depending on the peak position) even at high energy where very few photons were measured.

Hydrothermal synthesis of titanium dioxide nanoparticles studied employing in situ energy dispersive X-ray diffraction

Hydrothermal synthesis of titanium dioxide (TiO2) nanoparticles has been studied in situ using synchrotron radiation energy dispersive X-ray diffraction (EDXRD). The nanoparticles were produced from an acid (HNO3) and an alkaline (tetrabutylammonium hydroxide; TBA) peptized gel by hydrothermal treatment at 210 °C and 270 °C. The in situ EDXRD spectra clearly showed that pure TiO2 rutile phase nanoparticles were crystallized from HNO3 peptized gel, whereas pure anatase phase nanoparticles were produced from the TBA peptized gel. The EDXRD data shows that the rate of the particle formation increases with an increase in the process temperature for both processes. The powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) data confirms the in situ EDXRD results. The TEM images show that the anatase nanoparticles have relatively homogeneous particle size and morphology distribution whereas the rutile nanoparticles exhibit bimodal size and morphology distribution attributed to Ostwald ripening effect during the hydrothermal treatment.

The application of statistical methodology to the analysis of time-resolved X-ray diffraction data

We demonstrate for the first time the application of Principal Component Analysis (PCA) to the analysis of time-resolved energy-dispersive X-ray diffraction data. Previously well-characterised model systems are studied. PCA is shown to offer significant advantages over traditional curve-fitting methods in terms of speed and lack of potential user bias.

Energy dispersive X-ray diffraction spectroscopy for rapid estimation of calcite in copper ores

This article presents a novel technique for measuring the concentration of calcite in copper ore samples using energy dispersive X-ray diffraction (ED-XRD). The results are compared with ultraviolet fluorescence spectroscopy (UVF) for the same group of samples. This approach substantially shortens the measuring time with respect to the current laboratory procedures from 300 min down to 15 min and 9 min for energy dispersive X-ray diffraction and ultraviolet fluorescence spectroscopy, respectively, while preserving a good accuracy level (RMSE < 0.577). The models used for data processing were calibrated and validated for both techniques via the correlation coefficients ( R c 2 and R v 2 ), the error of prediction (RMSEP) and the error of calibration (RMSEC). R v 2 values between 0.88 and 0.94 were obtained for UVF and ED-XRD data, respectively. The calibration and validation were performed for calcite concentration ranges of 3.4–10.7% in the case of UVF and 2.9–7.6% for ED-XRD. The results reported show the potential of this method for on-line estimation of calcite concentration.

Time and position resolved in situ X-ray diffraction study of the hydrothermal conversion of gypsum monoliths to hydroxyapatite

Time-resolved energy dispersive X-ray diffraction (EDXRD) data have been measured in situ from cast blocks of gypsum, CaSO(4) x 2 H(2)O, in the presence of reactive phosphate solutions under hydrothermal conditions (100 < or = T < or = 180 degrees C) in order to understand the formation of hydroxyapatite monoliths, for applications such as in artificial bone or dental materials. Measurement of data in short (60 s) intervals has thus permitted information about the kinetics and mechanism of transformation of gypsum to hydroxyapatite to be obtained in a non-invasive way, avoiding the irreversible conversion of hydrous intermediate phases that would occur on quenching. At the lower temperatures used gypsum first converts to an amorphous intermediate phase during reaction, but as the temperature is raised to 130 degrees C and above, hydrothermal dehydration to the subhydrate CaSO(4) x 1/2 H(2)O always occurs before hydroxyapatite crystallises. The final crystal size of the hydroxyapatite is estimated from the peak broadening of the EDXRD data and this reveals an increase in crystal dimension with increasing reaction temperature. Comparing measurements from the surface and from the core of the blocks shows that an additional phosphate phase, CaHPO(4), is observed in the core at two temperatures and also that the crystal growth of hydroxyapatite does not penetrate the core of the block on the time scales we have investigated (up to 6 hours). The observations have important implications in the fabrication of hydroxyapatite monoliths from cast gypsum for applications, since the conversion via several intermediate phases may compromise the integrity and mechanical properties of the monoliths.

Thermal equation of state of CaGeO3 perovskite

Pressure-volume-temperature data have been obtained for CaGeO3 perovskite up to 9.6 GPa and 1100 K using a cubic anvil, DIA-type high-pressure apparatus in conjunction with synchrotron X-ray diffraction. The data were analyzed using Birch-Murnaghan equation of state and thermal pressure approach with the bulk modulus at ambient pressure, KT0, and its pressure derivative, K′T0, constrained by previous measurements. A fit of the unit-cell volume data to the high-temperature Birch-Murnaghan (HTBM) equation of state gives (∂KT/∂T)P = -0.025 ± 0.015 GPa/K, a = 1.047 ± 0.356 × 10-5/K, and b = 3.282 ± 0.735 × 10-8/K2 for the thermal expansion α expressed by a + bT. The thermal pressure approach yields αKT = 4.04 ± 0.37 × 10-3 GPa/K and (∂2P/∂T2)V = 6.17 ± 1.28 × 10-6 GPa/K2. The energy dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P-T range of the current experiment. A systematic relationship, KS0 = 6720/V(molar) - 13.07 GPa, has been established based on these isostructural analogues, which predicts KS0 = 261(15) for MgSiO3 perovskite and 225(8) for CaSiO3 perovskite, respectively.

The use of combined trace element XRF and EDXRD data as a histopathology tool using a multivariate analysis approach in characterizing breast tissue

AbstractThe concentrations of K, Fe, Cu and Zn were measured in 77 breast tissue samples (38 classified as normal and 39 classified as diseased) using x‐ray fluorescence (XRF) techniques. The coherent scattering profiles were also measured using energy‐dispersive x‐ray diffraction (EDXRD), from which the proportions of adipose and fibrous tissue in the samples were estimated. The data from 30 normal samples and 30 diseased samples were used as a training set to construct two calibration models, one using a partial least‐squares (PLS) regression and one using a principal component analysis (PCA) for a soft independent modelling of class analogy (SIMCA) technique. The data from the remaining samples, eight normal and nine diseased, were presented to each model and predictions were made of the tissue characteristics. Three data groups were tested, XRF, EDXRD and a combination of both. The XRF data alone proved to be most unreliable indicator of disease state with both types of analysis. The EDXRD data were an improvement, but with both methods of modelling the ability to predict the tissue type most accurately was by using a combination of the data. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Synthesis and structure of amorphous phaseCr(II) hemiporphyrazine using energy dispersive X-ray diffraction

A metal complex of general formula Cr (II)- C26H14N8has been obtained as an amorphous compound and studied by means of IR and Energy Dispersive X-ray Diffraction (EDXD). The chemical composition and the IR signals of the sample suggest that the hemiporphyrazine is bound to the metal atom via nitrogen atoms. EDXD data confirm this finding and show that the compound structure is composed of two parallel stacks of seven planar macro-molecules. The second stack is rotated by 5° around the z axis originating in its center of mass and the molecules are lying on parallel planes to xy plane.

High-pressure and high-temperature x-ray absorption study of liquid and solid gallium

Good quality extended x-ray absorption fine structure (EXAFS) spectra near the Ga K edge have been collected in wide pressure and temperature ranges (namely 0--16 GPa, 298--498 K) using the dispersive setup installed at the LURE synchrotron radiation facility and diamond anvil cell as pressure device. Energy dispersive x-ray diffraction data have been also measured in similar thermodynamical conditions. EXAFS spectra are shown to be sensitive to phase transitions occurring at high pressures and temperatures. Occurrence of stable and metastable phases and location of the coexistence lines are discussed in light of the results obtained using both experimental techniques. The phase diagram of pure gallium has been extended considering present experimental results. EXAFS data-analysis is performed using advanced ab initio methods (GNXAS). Accurate information about local structure in solid and liquid gallium at extreme conditions is obtained. The short-range two-body distribution functions are reconstructed by EXAFS for liquid and solid gallium as a function of pressure and temperature.

Rietveld refinements on laboratory energy dispersive X-ray diffraction (EDXD) data

Rietveld refinements of corundum, a rutile and anatase nanocrystalline synthetic mixture, and gypsum, on laboratory energy dispersive X-ray diffraction (EDXD) data are reported. Cell parameters, positional and displacement parameters are in reasonable agreement with single-crystal reference data, despite the rather poor resolution of EDXD data. In particular, good results were obtained for gypsum (unrestrained refinement) with counting times as short as 1000 s.

Pressure-induced phase transitions in bulk Zn 1− xMn xSe

Energy-dispersive X-ray-diffraction (EDXD) is used to study the pressure-induced transitions of Zn 1− x Mn x Se bulk samples, x=0.016, 0.026, 0.053, 0.07, and 0.24, below 30 GPa . The EDXD results show that possible structure transitions from the zinc blende (B3) to the sodium chloride phase (B1) for Zn 0.984Mn 0.016Se, Zn 0.974Mn 0.026Se, Zn 0.947 Mn 0.053Se, Zn 0.93Mn 0.07Se, and Zn 0.76Mn 0.24Se occur at 13.1, 12.4, 12.0, 11.8, and 9.6 GPa , respectively. The unloading run (the measurement with decreasing pressure) reveals that a reversible phase transition exists in the bulk Zn 1− x Mn x Se . In this work, our EDXD data show that the larger the increase of the fractional volume change at the phase transition from the B3 to the B1 region, the larger is the decrease of the reduction of the semiconductor-metal phase transition pressure.