Quantitative X-ray Research Articles

Storage and encryption of submicron spatial resolution X-ray images based on Ag-doped phosphate glass

The ultrastable encrypted storage of X-ray image with quantitative and ultrahigh-spatial resolution are crucial for a wide range of applications in radiation imaging, and it can be achieved by using the radio-photoluminescence (RPL) material, Ag-doped phosphate glass (Ag-PG), which was fabricated via the melt-quenching method. Under X-ray irradiation, Ag-PG produces a luminescence center, obvious 650 nm emission peak, which can be repeatedly excited by ultraviolet light without intensity attenuation. Quantitative X-ray image storage was realized based on the linear relationship between RPL intensity and X-ray irradiation time. X-ray image with a submicron spatial resolution of 0.7 µm was achieved, which could be stably stored without attenuation for more than 300 days. This submicron level X-ray image can be written into the Ag-PG as an encrypted information, and can only be visualized by an ultraviolet light. Additionally, heat treatment (400 °C for 2 h) could eliminate the influence of X-ray radiation on the Ag-PG, and restore the state of the Ag-PG before X-ray irradiation, which allows the recyclability and reusability of the Ag-PG. This research is of great significance for promoting the encrypted storage of X-ray images based on Ag-PG or other RPL materials.

Topotactic, Vapor-Phase, In Situ Monitored Formation of Ultrathin, Phase-Pure 2D-on-3D Halide Perovskite Surfaces.

Two-dimensional (2D) halide perovskites, HaPs, can provide chemical stability to three-dimensional (3D) HaP surfaces, protecting them from exposure to ambient species and from reacting with contacting layers. Both actions occur with 2D HaPs, with the general stoichiometry R2PbI4 (R: long or bulky organic amine) covering the 3D ones. Adding such covering films can also boost power conversion efficiencies of photovoltaic cells by passivating surface/interface trap states. For maximum benefit, we need conformal ultrathin and phase-pure (n = 1) 2D layers to enable efficient tunneling of photogenerated charge carriers through the 2D film barrier. Conformal coverage of ultrathin (<10 nm) R2PbI4 layers on 3D perovskites is challenging with spin coating; even more so is its upscaling for larger-area devices. We report on vapor-phase cation exchange of the 3D surface with the R2PbI4 molecules and real-time in situ growth monitoring by photoluminescence (PL) to determine limits for forming ultrathin 2D layers. We characterize the 2D growth stages, following the changing PL intensity-time profiles, by combining structural, optical, morphological, and compositional characterizations. Moreover, from quantitative X-ray photoelectron spectroscopy (XPS) analysis on 2D/3D bilayer films, we estimate the smallest width of a 2D cover that we can grow to be <5 nm, roughly the limit for efficient tunneling through a (semi)conjugated organic barrier. We also find that, besides protecting the 3D against ambient humidity-induced degradation, the ultrathin 2D-on-3D film also aids self-repair following photodamage.

Biomineralization in Barnacle Base Plate in Association with Adhesive Cement Protein.

Barnacles strongly attach to various underwater substrates by depositing and curing a proteinaceous cement that forms a permanent adhesive layer. The protein MrCP20 present within the calcareous base plate of the acorn barnacle Megabalanus rosa (M.rosa) was investigated for its role in regulating biomineralization and growth of the barnacle base plate, as well as the influence of the mineral on the protein structure and corresponding functional role. Calcium carbonate (CaCO3) growth on gold surfaces modified by 11-mercaptoundecanoic acid (MUA/Au) with or without the protein was followed using quartz crystal microbalance with dissipation monitoring (QCM-D), and the grown crystal polymorph was identified by Raman spectroscopy. It is found that MrCP20 either in solution or on the surface affects the kinetics of nucleation and growth of crystals and stabilizes the metastable vaterite polymorph of CaCO3. A comparative study of mass uptake calculated by applying the Sauerbrey equation to the QCM-D data and quantitative X-ray photoelectron spectroscopy determined that the final surface density of the crystals as well as the crystallization kinetics are influenced by MrCP20. In addition, polarization modulation infrared reflection-absorption spectroscopy of MrCP20 established that, during crystal growth, the content of β-sheet structures in MrCP20 increases, in line with the formation of amyloid-like fibrils. The results provide insights into the molecular mechanisms by which MrCP20 regulates the biomineralization of the barnacle base plate, while favoring fibril formation, which is advantageous for other functional roles such as adhesion and cohesion.

Comparison of Quantitative X-ray Diffraction Mineral Analysis Methods

X-ray diffraction (XRD) analysis, as one of the most powerful methods, has been widely used to identify and quantify minerals in earth science. How to improve the precision of mineral quantitative analysis is still a hot topic. To date, several quantitative methods have been proposed for different purposes and accompanied by diverse software. In this study, three quantitative mineral analysis methods, including the reference intensity ratio (RIR), Rietveld, and full pattern summation (FPS) methods, are compared and evaluated to systematically investigate their accuracy and applicability. The results show that the analytical accuracy of these methods is basically consistent for mixtures free from clay minerals. However, there are significant differences in accuracy for clay-mineral-containing samples. In comparison, it seems that the FPS method has wide applicability, which is more appropriate for sediments. The Rietveld method has been shown to be capable of quantifying complicated non-clay samples with a high analytical accuracy; nevertheless, most conventional Rietveld software fails to accurately quantify phases with a disordered or unknown structure. The RIR method represents a handy approach but with lower analytical accuracy. Overall, the present results are expected to provide a potentially important reference for the quantitative analysis of minerals in sediments.

Effect of prior [formula omitted] phase on precipitation kinetics of O-phase in advanced Ti2AlNb alloy

To study the influence of prior α2 phase on O-phase formation kinetics in β matrix, different isothermal heat treatments were performed at 876 and 780 °C using an advanced Ti2AlNb alloy with varying fraction of α2 phase. The kinetics of phase transformations was followed by electric resistivity measurements coupled to multi-scale microstructure characterization using scanning and transmission electron microscopy, energy dispersive X-ray spectrometry (EDS) and quantitative X-ray diffraction. It is revealed that the effect of α2 phase on the formation of O-phase depends on transformation temperature: while at 876 °C prior α2 precipitates lead to significantly slower formation of O-phase, as compared to α2 free alloy, the kinetics of O-phase formation is faster at 780 °C in the presence of α2 phase. Using EDS data as well as accurate measurements of lattice parameter of β phase, the diffusion character of O-phase formation in β matrix with and without prior α2 is shown for 876 °C while at 780 °C the diffusionless character of the O-phase formation is revealed for the beginning of the transformation followed by the partitioning of the alloying elements for prolonged treatment durations.

Early age hydration behavior of portland cement-based binders incorporating fly ash contaminated with flue gas desulfurization products

Fly ash co-mingled with flue gas desulfurization (FGD) products are currently discarded as off-specification materials based on their high SO3 content. However, previous studies have shown that performance of these fly ashes varies significantly based on FGD product type and as such they may be viable for use in low-CO2 concrete as supplementary cementitious materials (SCMs). In this study, fly ashes with three different types of FGD products including calcium sulfite hemihydrate, calcium sulfate (with some unreacted lime), and sodium sulfate (with some unreacted sodium carbonate) were evaluated. The early age hydration behavior in blended cementitious systems at 20% cement replacement level was studied using Vicat setting time tests, isothermal calorimetry, in-situ quantitative X-ray diffraction, and pore solution analysis. The cause of the setting time retardation and flash setting observed in fly ashes with calcium sulfite hemihydrate and sodium carbonate, respectively, were identified and suitable beneficiation options were suggested for the valorized use of these materials in low-CO2 concrete.

Experimental investigation on the spalling failure of a railway turnout made from Hadfield steel

In a rail track structure, a turnout is used as a transition between straight and branching rails and therefore withstands complex dynamic rolling and impact loading. This paper reports a comprehensive failure investigation of a railway off-track turnout made from Hadfield austenitic cast steel. The worn turnout was examined using optical microscopy, scanning electron microscopy, micro-hardness, and quantitative X-ray diffraction analyses. A ball-on-disc sliding wear test was also applied to evaluate the impact of work-hardening on the wear property. The turnout exhibited surface embrittlement, severe cracking, delamination, and spalling characteristics. Severe plastic deformation of the worn turnout was observed with the formation of densely packed mechanical twins, which facilitated crack propagation. The rail top developed a gradient hardness (HV0.1) profile from the rail top of 8.9 GPa, the cracked subsurface of 5.9 GPa to the bulk steel of 2 GPa. The rail top was also found to have accumulated an extremely high residual compressive stress of 500–650 MPa. Strain induced martensite transformation was repeatedly evidenced by X-ray diffraction peak of the ferritic (110) plane although the highly strained and nanocrystallised ferrite was only detected on the severely deformed rail top. Comparative sliding wear tests showed highly deteriorated wear resistance of the strain-hardened rail top as compared to the bulk steel.

Sub-resolution modeling of the apparent mass loss in quantitative broadband X-ray radiography

The quantitative impact of image blur on calculated object mass in X-ray radiography is explored. Radiographed object masses are initially estimated through experimental calibration and compared against their known true mass, with the deviation, or “apparent mass loss”. Apparent mass loss occurs due to the effect of spatial blur on X-ray transmission images that reduces the measured mass because while the image intensity is conserved with spatial blur, the nonlinear conversion to path length is not. A synthetic model is proposed where an object’s apparent mass loss is estimated through the amount of blur present within the radiograph image. The image blur is inferred through a combination of readily available image parameters related to the signal levels, object shape, and experimental extrinsics. A regularized regression model is built that correlates these blur parameters to the expected mass loss. The model is first trained on 2100 and tested on 140 synthetically created objects, and then later verified on two separate experimental setups of type 304 stainless steel objects imaged with a portable tube source at 150 kVp and type 6061 aluminum objects at 80 kVp. The proposed model allows for a simple post hoc reduction in errors of approximately 20% in object mass through X-ray radiography.

Micro-chemomechanical properties of red mud binder and its effect on concrete

Red mud is a hazardous waste generated from alumina production, and its safe disposal is a worldwide issue. Although some previous studies have reused red mud in cement-based composites, there is still a lack of research on the nano-scale chemomechanical properties of red mud binders. In this paper, atomic force microscopy with innovative QI™ mode, quantitative backscattered electron image, and quantitative x-ray diffraction analysis are conducted to uncover that Young's modulus of the C-(A)-S-H phase was decreased due to high content of red mud. The high porosity of corresponding binders allowed C-(A)-S-H gel to grow relatively unimpededly, resulting in lower packing density and lower modulus. The incorporation of red mud promoted the formation of aluminium-bearing phases and increased both Al/Ca, Si/Ca, and Fe/Ca ratio of formed C-(A)-S-H gel, especially for calcined red mud. At a moderate replacement ratio, the unreacted red mud enhanced the skeleton of the binder matrix with a filler effect. However, in concrete block samples, the size of red mud was insufficient to transfer the stress over limestone particles to mitigate the weak zones of blocks, and the reactivity of red mud always played a critical factor. Besides, recycling red mud in concrete blocks with a dry mix method overcomes the issue of workability reduction.

Geochemical modeling of CO2 sequestration in ultramafic mine wastes from Australia, Canada, and South Africa: Implications for carbon accounting and monitoring

Passive carbonation in ultramafic mine wastes results from the spontaneous reaction of gangue minerals with carbon dioxide (CO2) to form stable carbonate minerals that store CO2. Mines can benefit from unintentional CO2 sequestration to offset greenhouse gas (GHG) emissions. Quantitative X-ray diffraction (QXRD) analysis of numerous samples of mine wastes has typically been used to quantify passive carbonation rates. This analysis yields valuable information about carbon sinks; however, extensive mineralogical assessments are technically demanding and cost-prohibitive for routine carbon accounting. Alternatively, we explored using inverse geochemical modeling to estimate passive carbonation rates and monitor CO2 sequestration in active mines. Water chemistry data, tailings mineralogy, and operational information routinely collected by mines were used as inputs for models. The predictive capabilities of the models were tested for Mount Keith nickel mine (Australia), Diavik diamond mine (Canada) – for which rates were previously determined using QXRD. A new site — Venetia diamond mine (South Africa) — was used to illustrate the potential of geochemical modeling for carbon accounting and as a long-term monitoring tool for CO2 sequestration. Mount Keith models predicted passive carbonation rates (3900 g CO2/m2/yr) consistent with previous QXRD assessments (2400 g CO2/m2/yr; 172 samples) using only two water samples. CO2 removal rates for Diavik were found to be impacted by seasonality and to range between ∼375 and 510 g CO2/m2/yr, showing similarities with previous QXRD rates estimates (313–350 g CO2/m2/yr). With the long-term water chemistry records (2009–2018) available for Venetia mine, we predicted calcite as the main CO2 sink and that ∼14,875 t CO2 were stored in the kimberlite residues impoundments (3.5 km2) over 9 years at a rate of ∼470 g CO2/m2/yr. Moreover, long-term monitoring shows a decline in CO2 removal rates at Venetia, possibly due to changes in kimberlite reactivity and current mine waste disposal practices. Overall, inverse modeling proved that it can be a viable alternative or complement to QXRD techniques for carbon accounting in active mines, substantially reducing the need for mine waste sampling and permitting long-term monitoring. Moreover, the model shows how passive carbonation rates change dynamically with the mine production and waste management practices. Simultaneously, the model provides insights into potential mineral reactions operating in tailings and that regulate carbon sequestration mechanisms. For that reason, this accounting technique has an enormous potential to assist in decision-making for implementing enhanced CO2 sequestration strategies (e.g., enhanced rock weathering) and to support carbon sequestration monitoring, validation, and reporting in active mines.

Valgarður: a database of the petrophysical, mineralogical, and chemical properties of Icelandic rocks

Abstract. The Valgarður database is a compilation of data describing the physical and geochemical properties of Icelandic rocks. The dataset comprises 1166 samples obtained from fossil and active geothermal systems as well as from relatively fresh volcanic rocks erupted in subaerial or subaqueous environments. The database includes petrophysical properties (connected and total porosity, grain density, permeability, electrical resistivity, acoustic velocities, rock strength, and thermal conductivity) as well as mineralogical and geochemical data obtained by point counting, X-ray fluorescence (XRF), quantitative X-ray diffraction (XRD), and cation exchange capacity (CEC) analyses. The database may be accessed at https://doi.org/10.5281/zenodo.6980231 (Scott et al., 2022a). We present the database and use it to characterize the relationship between lithology, alteration, and petrophysical properties. The motivation behind this database is to (i) aid in the interpretation of geophysical data, including uncertainty estimations; (ii) facilitate the parameterization of numerical reservoir models; and (iii) improve the understanding of the relationship between rock type, hydrothermal alteration, and petrophysical properties.

Full-field quantitative X-ray phase nanotomography via space-domain Kramers–Kronig relations

Given the low absorption contrast of X-rays, phase shift has been playing an important role as an alternative source of contrast in X-ray nanoimaging. Numerous phase-measuring techniques have been proposed, most of which, however, are based on significant assumptions or sample translations. In this study, we propose the application of Kramers–Kronig (KK) relations in the spatial domain as a solution to allow the X-ray quantitative phase image to be directly calculated from the measured intensity image without any additional requirements. Based on this straightforward principle, we have presented KK nanotomography by introducing a spatial-frequency cutoff filter into a conventional tomographic setup. The robustness and versatility of the proposed method were experimentally verified based on various sample tomograms. We expect KK nanotomography to be widely adopted as a powerful and easy-to-adapt phase quantification solution for X-ray microscopes.

Characterisation and hydration kinetics of β-C2S synthesised with K2SO4 as dopant

In this study, a protocol for synthesising β-C2S using K2SO4 as a dopant has been reported. Quantitative X-Ray diffraction was used to characterise synthesised samples. It was observed that it is possible to synthesise β-C2S with high purity (>96 wt%) and limit the formation of free lime to below 0.5 wt% using this protocol. Unreactive γ-C2S was the main secondary phase present in the sintered samples. Isothermal calorimetry studies were conducted to understand the reaction kinetics which showed that β-C2S reacts slowly but produces similar calorimetric curve profiles as that of C3S. The C-S-H formed from the hydration of C2S was observed to be morphologically and compositionally identical to the C-S-H produced from the hydration of C3S. The hydration kinetics of β-C2S was seen to be affected by the presence of aluminosilicate pozzolan, such as calcined clay, which can have practical implications while producing blended cements with belitic clinkers.

Mineralogical and Microstructural Characterization of Cement-Stabilized Soft Soils Based on Quantitative Analyses

The effects of cement dosage (percentage by dry soil weight) and initial moisture content (wo) on cement stabilized soft estuarine clay were investigated by effective integration of multi-quantitative analyses, including quantitative X-ray diffraction (XRD), thermalgravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) test and scanning electron microscopy (SEM) with image processing. These quantitative analyses are highly complementary, which greatly improved the scientificalness of this research. The results revealed that the strength development of cement stabilized soft estuarine clay with varying cement dosages, and initial moisture content was ascribed to the combined influence of both soil fabric improvement and cementation bonding enhancement. The increase of wo resulted in larger clay particle spaces, which can counteract the enhancement of soil structure due to the rising hydration products. The hydration degrees of samples with fixed cement dosage but different wo are quite similar, while clay particle spaces were enlarged with an increase of initial moisture content. Thus, the same quantity of hydration products may bind more soil particles when pores are small at lower wo, thus increasing unconfined compressive strength (UCS). Furthermore, BET and quantitative SEM results illustrate that hydration degree plays a dominant role in the development of intra-aggregate pores (<0.2 μm), while wo affects inter-aggregate pores (0.2 μm–2 μm) more.

Evaluation of quantitative synchrotron radiation micro-X-ray fluorescence in rice grain.

Concentrations of nutrients and contaminants in rice grain affect human health, specifically through the localization and chemical form of elements. Methods to spatially quantify the concentration and speciation of elements are needed to protect human health and characterize elemental homeostasis in plants. Here, an evaluation was carried out using quantitative synchrotron radiation microprobe X-ray fluorescence (SR-µXRF) imaging by comparing average rice grain concentrations of As, Cu, K, Mn, P, S and Zn measured with rice grain concentrations from acid digestion and ICP-MS analysis for 50 grain samples. Better agreement was found between the two methods for high-Z elements. Regression fits between the two methods allowed quantitative concentration maps of the measured elements. These maps revealed that most elements were concentrated in the bran, although S and Zn permeated into the endosperm. Arsenic was highest in the ovular vascular trace (OVT), with concentrations approaching 100 mg kg-1 in the OVT of a grain from a rice plant grown in As-contaminated soil. Quantitative SR-µXRF is a useful approach for comparison across multiple studies but requires careful consideration of sample preparation and beamline characteristics.

Abstract TP92: Early Hyperacute Ion Dysregulation Following A Temporary Large Vessel Occlusion Stroke

Introduction: Ion dysregulation is a hallmark of energy failure after onset of ischemic stroke. To better understand the nature of the ion concentration changes in the early hyperacute phase after stroke onset we have quantitatively imaged the trace element distribution in the stroke lesion territory after a 30-minute temporary large vessel occlusion stroke. Methods: A temporary large vessel occlusion stroke was generated with the middle cerebral artery occlusion (MCAO) mouse model (insertion of an occluding filament via the ECA) with reperfusion after 30 minutes (occluding filament withdrawn). C57BL/6 mice (5 per time point) were euthanized at 5-, 30-, 60-, 90-, and 120-minutes post reperfusion. Shams included all surgical procedures, however the occluding filament was withdrawn immediately after insertion. Heads were immediately frozen post mortem and sectioned for trace element mapping. Quantitative X-ray fluorescence microscopy was performed at the Stanford Synchrotron Radiation Lightsource. Results: Loss of potassium is observed throughout the affected tissue at all post-reperfusion time points, with most of the initial loss occurring in the 30-minutes prior to reperfusion. Loss of essential zinc began to be observed 1-hour post reperfusion. No significant elevations in chlorine or calcium were observed during the early hyperacute phase. At subsequent post reperfusion time points the lesion (as defined by diminished potassium) grew steadily for 90-minutes. After 90-minutes post reperfusion some lesions demonstrated a distinct pattern consistent with a central infarct core surrounded by an ischemic penumbra. Conclusions: At all early hyperacute time points the stroke lesion demonstrated on-going potassium dysregulation, despite reperfusion. The loss of potassium was a bulk phenomenon in the tissue. Potassium is essential for maintenance of neuronal membrane potential and therefore function. Restoration of normal blood flow is insufficient to protect the brain from the enduring reduction in vital potassium levels or expansion of the region of ion dysregulation. The lack of available potassium within the affected tissue may hinder recovering neuronal cells from restoring action potentials, even after tissue perfusion is restored.

Phase volumes of ultra high performance concrete containing nanoscale pozzolan

Grid nanoindentation and quantitative X-ray diffraction are employed to provide quantitative information on phase constituents of nanoscale pozzolan-containing ultra-high-performance concrete (UHPC). Three UHPC samples containing nanoscale pozzolan and cured with and without microwave energy are investigated. The volume fraction of each phase constituent is independently evaluated using both techniques: nanoindentation (NI) and quantitative X-ray diffraction (QXRD). For the NI, the volumes have been evaluated by taking into account the thresholds characterising the phase constituents. The NI could assess phase mixtures or composites rather than single phases. The microwave-cured samples (CMW and CPMW) contain in total more hydration products that the sample that was not cured with microwave energy (C000). In all three samples, a nanocomposite (C–S–H/CHnm) consisting of high-density (HD) calcium silicate hydrate (C–S–H) and nanoscale portlandite (CH) is included, and its amount is more than double for the pressure-compacted and microwave-cured sample (CPMW). The heat curing by microwave energy together with the very low amount of water and restriction of the available space for hydration products, favour the formation of the nanocomposite (C–S–H/CHnm) in the CPMW sample.

Uncertainty of Quantitative X-ray Fluorescence Micro-Analysis of Metallic Artifacts Caused by Their Curved Shapes.

This paper summarizes the effects of irregular shape on the results of a quantitative X-ray fluorescence (XRF) micro-analysis. These effects become relevant when an XRF analysis is performed directly on an investigated material. A typical example is XRF analyses of valuable and historical objects whose measurements should be performed non-destructively and non-invasively, without taking samples. Several measurements and computer simulations were performed for selected metallic materials and shapes to evaluate the accuracy and precision of XRF. The described experiments and the corresponding Monte Carlo simulations were related to the XRF device designed and utilized at the Czech Technical University. It was found that the relative uncertainty was typically about 5-10% or even higher in quantitative analyses of minor elements due to irregular shapes of surfaces. This must be considered in cases of the interpretation of XRF results, especially in the cultural heritage sciences. The conclusions also contain several recommendations on how to measure objects under hard-to-define geometric conditions with respect to reduction in the surface effect in quantitative or semi-quantitative XRF analyses.

Simulating Knee-Stress Distribution Using a Computed Tomography-Based Finite Element Model: A Case Study

This study aimed to evaluate the mechanism of progression involved in knee osteoarthritis (OA). We used the computed tomography-based finite element method (CT-FEM) of quantitative X-ray CT imaging to calculate and create a model of the load response phase, wherein the greatest burden is placed on the knee joint while walking. Weight gain was simulated by asking a male individual with a normal gait to carry sandbags on both shoulders. We developed a CT-FEM model that incorporated walking characteristics of individuals. Upon simulating changes owing to a weight gain of approximately 20%, the equivalent stress increased extensively in both medial and lower leg aspects of the femur and increased medio-posteriorly by approximately 230%. As the varus angle increased, stress on the surface of the femoral cartilage did not change significantly. However, the equivalent stress on the surface of the subchondral femur was distributed over a wider area, increasing by approximately 170% in the medio-posterior direction. The range of equivalent stress affecting the lower-leg end of the knee joint widened, and stress on the posterior medial side also increased significantly. It was reconfirmed that weight gain and varus enhancement increase knee-joint stress and cause the progression of OA.

Thermally controlled structural strain reduction in core shell magnetoelectric nanocomposite

In this research, we have presented detailed studies of the effect of temperature-controlled hydrothermal fabrication techniques on the morphology and structural strain in magnetoelectric core-shell nanocomposite having magnetic CoFe2O4 core coated with a piezoelectric BaTiO3 shell. We have presented the effect of controlled cooling rate during annealing process of synthesis on the structural integrity and structural strain of the core-shell hetero-nanostructure. Using temperature controlled hydrothermal method, it has been observed that controlling the cooling rate to 20 °C/min while annealing process leads to low structural strain on the deposited BaTiO3 shell. This also leads to high structural integrity of the fabricated heterostructure nanocomposite. To measure the strain distribution in the coated shell, geometric phase analysis was performed on the high-resolution transmission electron microscopic image of the fabricated core-shell nanostructure. Semi quantitative Energy-dispersive X-ray spectroscopy line scan elemental mapping have confirmed the elemental distribution throughout the nanostructure and formation of the core–shell structure. Moreover, through the geometric phase analysis, the core and the shell can be distinctively visualized which confirms the homogeneity of the coating of single crystalline BaTiO3 shell on the CoFe2O4 core.