Energy-dispersive X-ray Spectroscopy Images Research Articles

Image enhancement and microstructure characterization of energy dispersive X-ray spectroscopy images of blended cement pastes

Energy dispersive X-ray spectroscopy (EDS) image analysis has been widely used to study the microstructure of cementitious materials, whereas in some cases the efficiency of the characterization suffered from the extremely long time for image acquisition. In this study, we proposed an EDS image analysis methodology including image enhancement, phase extraction, and characterization of reaction products. The guided filter and Logarithm correction were combined and employed to improve the resolvability of low-quality EDS images. Gaussian Mixture Model (GMM) algorithm was applied to segment the unreacted phases and two different groups of reaction products from the enhanced EDS images. Moreover, the spatial distribution and chemical composition of reaction products were characterized using the lineal-path function and simple lineal iterative clustering (SLIC) algorithm. Results showed that low-quality EDS images after enhancing could achieve the comparable performance with high-quality EDS images in terms of the phase proportions. This study offers a practical and effective methodology for enhancing and analyzing the low-quality EDS images, giving insights into the phase assemblage and microstructure evolution of cementitious materials.

Assessment of dissimilar friction stir welded AA6061/SS316 for sustainable industry

Energy and environmental issues have played an important role in developing sustainable industries. The incorporation of lightweight materials into various structures enables a reduction in both weight and fuel consumption, resulting in saving energy. So, the selection of material and joining techniques have contributed significantly in these problems. This paper focused on the assessment of dissimilar lap-joint between AA6061 to SS316 using green technology as friction stir welding. The effect of welding parameters on the properties of joints was assessed. The test results showed that the welding interface is sensitive to rotational speed. The joint with the highest strength is approximately 6200 N at 700 rpm. In this case, the joint was fractured in heat effected zone on the aluminum side. The welding interface was revealed by using scanning electron microscope and energy-dispersive X-ray spectroscopy images to analyze the joint quality.

Cutting fluid role in the machinability of AZ91/SiC composite: Tool wear and surface roughness

Metal matrix composites (MMC) introduced special features such as resistance to wear and high strength to weight ratio and these characteristics categorized them as difficult-to-cut materials in the field of machining. In the current paper, a novel study on the cutting fluid emulsion 5% role in the machinability of a magnesium-based metal matrix composite reinforced by silicon carbide (SiC) particles is presented. AZ91 magnesium alloy, with nominal composition Mg-9Al-1Zn, composites were made using stir casting method. Then, the composite samples were machined and the cutting parameters such as cutting speed, feed rate and side cutting edge angle were varied to assess their effects on the wear and surface roughness. To measure and analyze the wear, optical and scanning electron microscope (SEM) were used. Also, elemental analysis through energy-dispersive X-ray spectroscopy (EDS) was accomplished. Surface roughness of machined samples were measured by a profilometer and 3D surface topography. Results of SEM and EDS images indicated that SiC particles included in the composites act as grinders and remove the surface of tool even in a short time because of the severe abrasion. Additionally, surface of machined MMCs contains some defects such as cracks, broken SiC, and unwanted deformations. Using cutting fluid emulsion 5% enhanced the tool life as well as the surface quality remarkably for different cutting speeds, feed rates and cutting edge angles although finished surface of the samples were oxidized. Also, the cutting fluid considerably reduced the amount of adhered materials on the flank face.

A comprehensive intelligent framework for interpreting and quantifying the microstructure of waste-derived alkali-activated materials: A case study of fly ash/slag pastes

The alkali-activated fly ash/slag (AAFS) pastes exhibit complex compositions and heterogeneous spatial distributions of phases, necessitating a comprehensive tool capable of quantifying phase assemblage, characterizing ion diffusion, and unveiling microstructure evolution. However, existing techniques have limitations in providing interpretability and visual analyses. This study introduces a versatile analysis methodology for energy dispersive X-ray spectroscopy (EDS) images, encompassing data preprocessing, data interpretation, and four downstream applications: phase inference, phase quantification, ion diffusion characterization, and quantification of phase spatial distributions. Through the analysis of five representative elements, this study successfully identifies and quantifies three components in precursors (slag, quartz, mullite) and four reaction products (slag-products, quartz-products, mullite-products, mixture products) in the AAFS pastes. Moreover, by characterizing ion diffusion and quantifying spatial distributions, insights into the interactions among various precursors and reaction products are elucidated. The proposed EDS image analysis methodology is expected to yield valuable understandings of the reaction mechanisms and phase evolution involved in utilizing solid waste as cementitious materials.

Quantifying the phase assemblage in the hydrated cement paste by an interpretable and automatic EDS image analysis framework

The Energy dispersive X-ray spectroscopy (EDS) data, characterized by high dimensionality, low resolution, and large scale, necessitates a robust characterization method that is both easy to understand and delicate to reveal the underlying information. Here, we present a practical and interpretable framework for quantitative EDS (QEDS) image analysis. To improve the quality of data, we employ sequential processing techniques including guided filter, linear enhancement, and super-pixel segmentation. For phase identification and classification, the dimensionality reduction algorithm Potential of heat-diffusion for affinity-based transition embedding (Phate) was integrated with cluster analysis algorithm Gaussian Mixture Model (GMM). This integration cleanly and clearly reveals typical data patterns such as linear progressions and local clusters, indicating the presence of phase evolution and representative phases. We expect that this QEDS image analysis offers an intuitive and visual way to quantify the phase assemblage in cementitious systems, thereby shifting the quantification process from expert knowledge-dominated “black boxes” into data structure-dominated “glass boxes”.

Three-dimensional reconstruction of Y-IrNi rhombic dodecahedron nanoframe by STEM/EDS tomography

The structural analysis of nanocrystals via transmission electron microscopy (TEM) is a valuable technique for the material science field. Recently, two-dimensional images by scanning TEM (STEM) and energy-dispersive X-ray spectroscopy (EDS) have successfully extended to three-dimensional (3D) imaging by tomography. However, despite improving TEM instruments and measurement techniques, detector shadowing, the missing-wedge problem, X-ray absorption effects, etc., significant challenges still remain; therefore, the various required corrections should be considered and applied when performing quantitative tomography. Nonetheless, this 3D reconstruction technique can facilitate active site analysis and the development of nanocatalyst systems, such as water electrolysis and fuel cell. Herein, we present a 3D reconstruction technique to obtain tomograms of IrNi rhombic dodecahedral nanoframes (IrNi-RFs) from STEM and EDS images by applying simultaneous iterative reconstruction technique and total variation minimization algorithms. From characterizing the morphology and spatial chemical composition of the Ir and Ni atoms in the nanoframes, we were able to infer the origin of the physical and catalytic durability of IrNi-RFs. Also, by calculating the surface area and volume of the 3D reconstructed model, we were able to quantify the Ir-to-Ni composition ratio and compare it to the EDS measurement result.

Preparation of platinum-free manganese oxide (MnOx) catalyst film for H2O2 decomposition in contact-lens cleaning

A platinum (Pt)-free manganese oxide (MnOx) catalyst film for H2O2 decomposition was prepared on an aluminum (Al) substrate (MnOx/Al) by a hydrothermal impregnation method to decrease the cost of a container used in contact lens cleaning and effectively using Pt materials as other several catalysts. Scanning electron microscopy with energy dispersive X-ray spectroscopy images confirmed that the Al substrate was covered with MnOx. The thickness of the MnOx film was about 300 nm. X-ray diffraction spectra showed that the MnOx film consisted of MnO2 and Mn2O3. The catalytic activity for H2O2 decomposition was estimated by measuring the residual H2O2 concentration, and the target value was ≦100 ppm. The MnOx/Al catalyst was immersed in 35,000 ppm H2O2 solution for 360 min, then the H2O2 concentration decreased to 737 ppm. This result indicated that the MnOx catalyst had a high catalytic activity for H2O2 decomposition but it was not enough for practical use. To improve the catalytic activity, an Al substrate was roughened to increase the specific surface area before preparing an MnOx film. A method with the highest effect of increase in surface roughness was a combination of sandblasting and chemical etching. An MnOx catalyst film was prepared on the roughened Al substrate (MnOx/roughened-Al). When the MnOx/roughened-Al catalyst was immersed in 35,000 ppm H2O2 solution for 360 min, the H2O2 concentration decreased to 38 ppm. When the catalyst was used repeatedly for 10 times, the residual H2O2 concentration was 66 ppm, which indicated that the Pt-free catalyst also had high catalytic durability. These results demonstrated that a roughening was extremely effective in improving both the catalyst activity and durability of a MnOx film catalyst, and a conventional catalyst of a Pt plating film can be replaced with the developed catalyst of the MnOx film on the roughened Al substrate.

Structural, morphological, and photoluminescence properties of RE (RE = Dy3+ , Eu3+ , Sm3+ )-doped CaAlBO4 phosphor synthesized by combustion method.

The CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor were prepared via combustion synthesis and studied by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectra and CIE coordinates. The phase formation of the obtained phosphor was analyzed by XRD and the result was confirmed by standard PDF Card No. 1539083. XRD data successfully indicated pure phase of CaAlBO4 phosphor. The crystal structure of CaAlBO4 phosphor is orthorhombic with space group Ccc2 (37). The SEM image of CaAlBO4 phosphor reveals an agglomerated morphology and non-uniform particle size. The EDS image provides evidence of the elements present and the chemical makeup of the materials. Under the 350 nm excitation, the emission spectrum of Dy3+ activated CaAlBO4 phosphor consists of two main groups of characteristic peaks located at 484 and 577 nm which are ascribed to 4 F9/2 → 6 H15/2 and 4 F9/2 → 6 H13/2 transition of Dy3+ respectively. The PL emission spectra of CaAlBO4 :Eu3+ phosphor shows characteristics bands observed around 591 and 613 nm, which corresponds to 5 D0 → 7 F1 and 5 D0 → 7 F2 transition of Eu3+ respectively, upon 395 nm excitation wavelength. The emission spectra of Sm3+ activated CaAlBO4 phosphor shows three characteristic bands observed at 565, 601 and 648 nm which emits yellow, orange and red color. The prominent emission peak at the wavelength 601 nm, which is attributed to 4 G5/2 → 6 H7/2 transition, displays an orange emission. The CIE color coordinates of CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor are calculated to be (0.631, 0.368), (0.674, 0.325) and (0.073, 0.185). As per the obtained results, CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor may be applicable in eco-friendly lightning technology.

Soft X-ray microspectroscopic imaging studies of exfoliated surface between fluoropolymer and Cu plate directly bonded by plasma irradiation with ammonia gas

The F, C, O, and N elemental distribution maps at the exfoliated surfaces of Cu plate after peeling the fluoropolymers from Fluorinated ethylene propylene (FEP)/Cu and Perfluoroalkoxyalkane (PFA)/Cu pieces which were bonded by plasma treatment including amino acid were performed by microscopic synchrotron radiation (SR) spectroscopic imaging measurements. The spatial elemental distribution pattern of exfoliated Cu after peeling PFA/Cu piece was not detectable by scanning electron microscopy with energy dispersive X-ray spectroscopy imaging alone, was revealed by SR-based soft X-ray microspectroscopy. We also obtained the microprobe X-ray fluorescence spectra and microprobe near-edge X-ray absorption fine structure spectra. Based on these measurement results, it is considered that the delamination of FEP/Cu piece mainly caused by resin failure, while the delamination of PFA/Cu is caused by interfacial delamination in addition to resin failure. The Hard X-ray photoelectron spectroscopy was also performed to confirm that the bonding via nitrogen is formed. Our SR-based analyses provided confirmation that fluoropolymers and Cu plates are bonded by N-mediated chemical bonding. The present study insists that the technique and plasma bonding process reported are expected to contribute to the development of new devices and systems consisting of fluoropolymers and metals.

Quantifying the microstructure evolution and phase assemblage of solid waste as construction materials by EDS image analysis: A case study of carbonated basic oxygen furnace slag aggregates

The diversities of raw materials and manufacturing techniques lead to large fluctuations in the upcycling potential of solid waste as construction materials. A quantitative energy dispersive X-ray spectroscopy (EDS) image analysis methodology was developed to measure the microstructure evolution and phase assemblage of solid waste. Based on the proposed EDS image enhancement algorithm, the component complexity and structural heterogeneity of basic oxygen furnace slag (BOFS) can be fully revealed by the EDS images. Thereafter, the proportions of major phases (i.e., pores, reaction products, and unreacted components) and the specific composition information of involved phases can be determined. The spatial distributions of reaction products and unreacted components could be studied by the lineal-path distribution function and the phase assemblage of reaction products could be studied by the elemental ratios. The results showed that the effects of subsequent hydration on the microstructural and mineralogical alterations of carbonation products were more prominent than the consumption of unreacted components. The continuous dissolution of the Ca and Si ions upon the hydration significantly promoted the transformation of carbonation products and microstructure densification of BOFS aggregates, which was the main contributor to the development of mechanical performance.

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Roll-to-roll solvent-free manufactured electrodes for fast-charging batteries

Preparation, Characterization, and Wound Healing Assessment of Curcumin-Loaded M-MOF (M = Cu, Zn)@Polycaprolactone Nanocomposite Sponges.

The fabrication of multifunctional scaffolds has attracted much attention in biological fields. In this research, some novel composites of Cu(II) or Zn(II) metal-organic framework (M-MOF) and polycaprolactone (PCL), M-MOF@PCL, have been fabricated as multifunctional scaffolds for application in the tissue engineering (TE) field. The porous three-dimensional sponges were prepared by the salt leaching method. Then, the M-MOF@PCL composite sponges have been prepared by in situ synthesis of M-MOF in the presence of the as-obtained PCL sponge to gain a new compound with proper features for biological applications. Finally, curcumin was attached to the M-MOF@PCL as a bioactive compound that can act as a wound-healing agent, anti-oxidant, and anti-inflammatory. The presence of the M-MOF in final composites was investigated by different methods such as FTIR (Fourier-transform infrared), XRD (X-ray diffraction), SEM (scanning electron microscope), EDS (energy-dispersive X-ray spectroscopy), and TEM (transmission electron microscope). SEM images confirmed the porous structure of the as-obtained composites. According to the EDS and TEM images, M-MOFs were uniformly incorporated throughout the PCL sponges. The water sorption capacities of the blank PCL, Cu-MOF@PCL, and Zn-MOF@PCL were determined as 56%, 155%, and 119%, respectively. In vivo investigation on a third-degree burn model in adult male Wistar rats exhibited an accelerated wound healing for Cu-MOF@PCL compared to with Zn-MOF@PCL and the control group.

Cytotoxicity effect of nanoparticles of Euphorbia antiquorum on breast cancer cell line

Euphorbia antiquorum was known for its various therapeutic values like anti-inflammatory, anti-diabetic activity etc. Preliminary phytochemicals screening of plant extract disclosed the existence of various important bioactive constituents in hexane, ethanol and aqueous extract of the plant. Aqueous extract of Euphorbia antiquorum was used for silver and copper nanoparticle synthesis. Synthesized silver and copper nanoparticle showed the absorbance line at 422 and 367 nm respectively. Fourier-transform infrared spectroscopy analysis of synthesized nanoparticles reported the presence of phenol groups, amines and esters. Shape and morphology of the synthesized nanoparticles were characterized through Field Emission Scanning Electron Microscopy which showed the spherical shaped nanoparticles. Energy dispersive X-ray spectroscopy images showed the composition of analysed nanoparticles. The antioxidant activity of synthesized silver and copper nanoparticles of Euphorbia antiquorum by hydrogen peroxide scavenging activity method using ascorbic acid as the standard showed effective scavenging activity and indicated the potentiality of the plant as a source of natural antioxidant. Cytotoxicity study of silver nanoparticles showed 73.22% of inhibition at the concentration of 1000 µg/ml whereas copper nanoparticles at the same concentration showed 68.85% of inhibition against breast cancer cell line.

Physico-chemical properties of chitosan extracted from Whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka

The present study investigated the potential of whiteleg shrimp shell waste to use as a source of chitosan which has a limited focus on previous Sri Lankan studies. Comparatively higher amount of chitosan yield (33.53%) was obtained in the study with 91.78 ± 0.66 (%) of dry matter content, 8.22 ± 0.66 (%) of moisture content, 1.08 ± 0.24 (%) of ash content, 80.43% of the degree of deacetylation, 435.87 ± 1.03 cP dynamic viscosity and a good thermal stability up to 312 °C. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the structure of chitin and chitosan by the presence of their characteristic IR bands and X-ray diffraction analysis further verified the crystalline structure of the extracted chitin and chitosan. Scanning electron microscopic (SEM) images of the extracted chitosan recognized the layers of flakes with porous and fibril structures. According to the energy-dispersive X-ray spectroscopy image, carbon, oxygen and nitrogen were observed as the major elements in the extracted chitosan and no calcium peaks were detected confirming effective demineralization in the extraction process. Further, DPPH (2,2-diphenyl-1-picryl hydrazy) assay revealed that the chitosan solution with the concentration of 10 mg/mL was having 66.45% of free radical scavenging activity. Thus, the present study reveals that the chitosan with high quantity and quality can be extracted from whiteleg shrimp (Litopenaeus vannamei) processing shell waste in Sri Lanka suggesting a solution to the waste accumulation in processing factories while proposing an alternative income generation strategy from waste.

Measuring the hydration product proportion in composite cement paste by using quantitative BSE-EDS image analysis: A comparative study

Composite cement has attracted increasing interest in the construction material field from the view of environmental and economic benefits. However, the measurement of hydration product proportion in the composite cementitious system remains challenging due to the heterogeneity of components and the existence of amorphous phases. In this study, three grey value histogram-based Backscattered Electron (BSE) image analysis approaches were compared mutually at first. Then, two color clustering-based Energy Dispersive X-ray Spectroscopy (EDS) image analysis approaches are comparatively developed for intuitively quantifying the hydration product proportion. In the BSE image analysis, results indicate that Overflow Method and Gaussian Mixture Model (GMM) show more reliable and accurate results than Frequency Histogram Method. In the EDS image analysis, GMM is better than K-means in terms of accuracy and reproducibility, and the cluster number of three sufficiently meets the requirement of grain extraction. Finally, the BSE-EDS image analysis, which integrates the merits of above approaches was proposed, achieving the best measurement performance. The hydration product proportions determined by BSE, EDS, and BSE-EDS image analysis approaches in the current research are 73.5%, 74.7%, and 68.1%, respectively. The proposed BSE-EDS image analysis offers a way to identify the hydration products practically, reliably, and visually in the cementitious system.

Rechargeable alkaline Zn–Cu batteries enabled by carbon coated Cu/Bi particles

In this work, we demonstrate using Cu as the cathode active material in alkaline Zn batteries by forming nanoscale carbon coated Cu/Bi particles through the carbonization of dopamine coated CuO/Bi2O3. The resulting particles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental analysis (EA), and Raman spectroscopy. The carbon coating was found to be roughly 20 nm thick with a mass loading of ∼8 wt%. When cycled versus pasted Zn anodes, the Cu/Bi@C cathodes provided 200 cycles at ∼300 mAh/g and ∼100 Wh/L. SEM, EDS, XRD, and optical images were used to track changes in the electrode structure and morphology over the first 50 cycles. Solubility of Cu and Bi species was found to decrease the capacity during the first 10 cycles, followed by minimal losses thereafter. The carbon coating enables consistent cycling performance and prevents the formation of detrimental Cu2O structures found in passivated Zn/CuO batteries. This work exemplifies the benefits of nanoscale carbon coatings for Cu particles providing further insight into methods for realizing a Cu based cathode for rechargeable alkaline Zn batteries.

Insights on chemical and physical chloride binding in blended cement pastes

This study investigates chloride binding in blended cement pastes exposed to 0.5 M NaCl solutions (with and without pH adjustment) using X-ray diffraction and energy-dispersive X-ray spectroscopy image analysis (edxia). The aim is to better understand the effects of the binder type, the water-to-binder ratio and the pH on the chemical binding in AFm phases and the physical binding on C-A-S-H. Results show that the binding cannot be predicted from AFm and C-A-S-H contents alone because competing ions in the system affect both the Friedel's salt solid solution chemistry and the C-A-S-H binding capacity. Notably, the high content of aluminous hydrates in LC3 systems leads to a high chemical binding even if Friedel's salt solid solutions have relatively low chloride contents (particularly at a higher pH). On the contrary, the CEMIII/A paste showed low binding because of relatively high sulfate and magnesium contents which compete for incorporation/adsorption in aluminous hydrates (AFm, ettringite and hydrotalcite).

Effectiveness of a Nanohydroxyapatite-Based Hydrogel on Alveolar Bone Regeneration in Post-Extraction Sockets of Dogs with Naturally Occurring Periodontitis.

Pathological mandibular fracture after dental extraction usually occurs in dogs with moderate to severe periodontitis. A nanohydroxyapatite-based hydrogel (HAP hydrogel) was developed to diminish the limitations of hydroxyapatite for post-extraction socket preservation (PSP). However, the effect of the HAP hydrogel in dogs has still not been widely investigated. Moreover, there are few studies on PSP in dogs suffering from clinical periodontitis. The purpose of this study was to evaluate the effectiveness of the HAP hydrogel for PSP in dogs with periodontitis. In five dogs with periodontitis, the first molar (309 and 409) of each hemimandible was extracted. Consequently, all the ten sockets were filled with HAP-hydrogel. Intraoral radiography was performed on the day of operation and 2, 4, 8 and 12 weeks post operation. The Kruskal–Wallis test and paired t-test were adopted for alveolar bone regeneration analysis. The results demonstrated that the radiographic grading, bone height measurement, and bone regeneration analysis were positively significant at all follow-up times compared to the day of operation. Moreover, the scanning electron microscopy with energy-dispersive X-ray spectroscopy imaging after immersion showed a homogeneous distribution of apatite formation on the hydrogel surface. Our investigation suggested that the HAP hydrogel effectively enhances socket regeneration in dogs with periodontitis and can be applied as a bone substitute for PSP in veterinary dentistry.

Atomic-resolution STEM-EDS studies of cation ordering in Ti-Nb oxide crystals

Ternary metal oxide compounds, such as Ti-Nb and Nb-W oxides, have renewed research interest in energy storage materials because these oxides contain multivalent metal ions that may be able to control the ion transport in solid lithium batteries. One of these oxides is Ti2Nb10O29, which is composed of metal–oxygen octahedra connected through corner-sharing and edge-sharing to form “block structures”. In the early 1970s Von Dreele and Cheetham proposed a metal-atoms ordering in this oxide crystal using Rietveld refined neutron powder diffraction method. Most recent studies on these oxides, however, have not considered cation ordering in evaluating the battery electrode materials. In this paper, by utilizing the latest scanning transmission electron microscopy combined with energy dispersive X-ray spectroscopy imaging technology, the cation chemical ordering in those oxide crystals was directly revealed at atomic resolution.

Ambient energy dispersion and long-term stabilisation of large graphene sheets from graphite using a surface energy matched ionic liquid†

Liquid phase exfoliation (LPE) is the most promising method for scalable graphene production, but conventionally requires significant energy input to break apart layers in the bulk material, introducing defects and limiting production of large, few-layer sheets. In this work, we exfoliated graphene under ambient conditions with minimal external energy input using the surface energy matched ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EMIm Ac), then isolated and characterised the exfoliated material. This method produced large and thin, graphene sheets with size up to 3 μm. Monolayer sheets were identified in samples that had been left undisturbed for 6 months prior to sampling, meaning the graphene sheets suspended in the ionic liquid are stabilized against restacking; to our knowledge, this is the longest period of time large (non-oxidised) graphene monolayers have been suspended in any liquid. Molecular dynamics simulations show the IL cation is enriched at the graphene surface. We postulate this leads to a positive charge on the graphene sheets in EMIM Ac leading to an electrostatic repulsion which contributes to colloidal stability. Strong adsorption of the EMIM cation to graphene is confirmed by energy dispersive X-ray spectroscopy images that show ionic liquid adsorbed to graphene sheets even after washing. Ambient energy exfoliation using ionic liquids offers simple, energy efficient method for producing large, high quality graphene sheets, with long-term stability in the ionic liquid. [Display omitted]