X-ray Absorption Near-edge Spectroscopy Analysis Research Articles

Local structural and sensing properties of TiO2 thin film using the PVD method

This paper studied the structural, morphological, optical, and X-ray absorption near-edge spectroscopy (XANES) and sensing properties of titanium dioxide (TiO2) thin film. The TiO2 thin film is prepared in the thin film laboratory on a clean glass plate using a physical vapor deposition (PVD) method. The structural, morphological, Optical, and electronic properties of the fabricated samples are presented by X-ray diffraction (XRD), atomic force microscope (AFM), UV-visible, and XANES. It is found from XRD the crystallite size was ∼25.66 nm with microstrain ∼0.0064 using the Williamson-Hall (W-H) plot. The fractal terms such as grain size, roughness, kurtosis, and skewness were estimated using AFM. The grain size lies in the nanometric range and found that ∼77.21 nm. The band gap of the fabricated film is ∼3.23 eV. The XANES analysis is well supported by XRD measurement and the result found that the fabricated TiO2 thin film was anatase phase. The sensing properties of TiO2 are studied for the detection of Liquified Petroleum Gas (LPG) concentration (0-5000 ppm) at room temperature. Results found that the TiO2 film is highly sensitive and is the fast response for LPG gas sensors with a maximum sensitivity of ∼198 %.

Toward Understanding the Environmental Risks of Combined Microplastics/Nanomaterials Exposures: Unveiling ZnO Transformations after Adsorption onto Polystyrene Microplastics in Environmental Solutions.

Over recent decades, there has been a dramatic increase in the manufacture of engineered nanomaterials, which has inevitably led to their environmental release. Zinc oxide (ZnO) is among the more abundant nanomaterial manufactured due to its advantageous properties, used for piezoelectric, semiconducting, and antibacterial purposes. Plastic waste is ubiquitous and may break down or delaminate into smaller microplastics, leaving open the question of whether these small polymers may alter the fate of ZnO through adsorption within aquatic media (tap-water and seawater). Here, scanning electron microscopy analysis confirms the effective Zn nano/microstructures adsorption onto polystyrene surfaces after only 24-h incubation in the aquatic media. After pre-aging the nanomaterials for 7-days in different environmental media, nanoprobe X-ray absorption near-edge spectroscopy analysis reveals significant ZnO transformation toward Zn-sulfide and Zn-phosphate. The interaction between a commercial ZnO-based sunscreen with polystyrene and a cleanser consumer containing microbeads with ZnO nanomaterials is also studied, revealing the adsorption of transformed Zn-species in the microplastics surfaces, highlighting the environmental relevancy of this work. Understanding the structural and functional impacts of the microplastics/ZnO complexes, and how they evolve, will provide insights into their chemical nature, stability, transformations, and fate, which is key to predicting their bioreactivity in the environment.

Neurotoxicity study of lead-based perovskite nanoparticles

Lead-based halide perovskite nanoparticles (Pb-PNPs) are promising alternatives for the next-generation of optoelectronic materials, while their nonnegligible biological behavior after exposure are still an enigma. Here, we clarify the translocation, biotransformation, and biodistribution related neurotoxicity of representative CsPbBr3 PNPs in C57BL/6J mice after intranasal administration through a combination of the feat of advanced synchrotron radiation (SR) and traditional analytical techniques. SR-based microscopic X-ray fluorescence scanning, inductively coupled plasma mass spectrometry and behavioral data demonstrate that CsPbBr3 PNPs can be transported and accumulated in the hippocampus, easily triggering Ca overload, causing severe damage of hippocampus-dependent learning, memory, and cognition behavior. Meanwhile, SR–based X-ray absorption near-edge spectroscopy analysis also reveals that CsPbBr3 PNPs can transform into soluble and insoluble lead compounds in different physiological environments. The toxicity of CsPbBr3 PNPs is higher than that of soluble Pb(Ac)2 due to the sustained release of Pb ions. The CsPbBr3 PNPs cause nerve cell apoptosis through triggering intracellular Ca2+ overload, upregulating reactive oxygen species production, while disordering the mitochondrial membrane potential. Our work provides significant insights into the neurological effects and mechanism of Pb-PNPs.

Cu and As containing pigments in Zhejiang architecture polychrome paintings: a case study of degradation products of emerald green

The discoloration of pigments caused by deterioration may significantly alter an artifact's original pattern and design, which could have an impact on its intended meaning. The green pigments containing copper (Cu) and arsenate (As) in paintings are usually recognized as Emerald green or Scheele’s green and are also infrequently reported as cornwallite and lavendulan. Recent studies point out that lavendulan may be the degradation product of Emerald green but not a natural mineral. Overall, there are still relatively few cases of current studies on green pigment with Cu and As. The elemental composition and molecular structure of green minerals containing Cu and As are similar, so it is difficult to identify by Raman spectroscopy. The green pigment samples used in this investigation were taken from architectural paintings in the Wenchang palace and traditional Ziweishan dwellings. The composition of the paint samples was investigated comprehensively by Raman spectroscopy, scanning electron microscope observation, micro-X-ray diffraction (μ-XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) analysis. From the results of elemental distribution, the pigments mainly contain Cu, As, and Cl. The morphological results illustrated that the particles in these three pigments are rounded and granular, indicating the synthetic pigment is possibly emerald green. The characteristic vibrational peaks of the As–O, Cu–O and Cu–Cl bond were detected by Raman spectroscopy, and infrared spectroscopy found the presence of oxalate salt. The XPS and XANES analysis results show that As valence is + 5. This study found that the green pigment samples are a degradation product of emerald green. The formation of this product is related to the preservation environment. The results of this work will provide information to understand the degradation processes of emerald green and be a reference for the identification of pigments containing Cu and As elements.

Engineering adjacent N, P and S active sites on hierarchical porous carbon nanoshells for superior oxygen reduction reaction and rechargeable Zn-air batteries

Heteroatom-doped carbon materials have been regarded as sustainable alternatives to the noble-metal catalysts for oxygen reduction reaction (ORR), while the catalytic performances still remain unsatisfactory. Herein, we develop a metal-free adjacent N, P and S-codoped hierarchical porous carbon nanoshells (NPS-HPCNs) through a novel layer-by-layer template coating method. The NPS-HPCNs is rationally fabricated by crosslinking of polyethyenemine (PEI) and phytic acid (PA) on nano-SiO2 template surface and subsequently coating of viscous sulfur-bearing petroleum pitch, followed by pyrolysis and alkaline etching. Soft X-ray absorption near-edge spectroscopy (XANES) analysis and density functional theory (DFT) calculations prove the engineering of adjacent N, P and S atoms to generate synergistic and reinforced active sites for oxygen electrocatalysis. The NPS-HPCNs manifests excellent ORR activity with a half-wave potential (E1/2) of 0.86 V, as well as promoted durability and methanol tolerance in alkaline medium. Remarkably, the NPS-HPCNs-based Zn-air battery delivers an open-circuit voltage of 1.479 V, a considerable peak power density of 206 mW cm−2 and robust cycling stability (over 200 h), even exceeding the commercial Pt/C catalyst. This study offers fundamental insights into the construction and synergistic mechanism of adjacent heteroatoms on carbon substrate, providing advanced metal-free electrocatalysts for Zn-air batteries and other energy conversion and storage devices.

Microbially influenced tungsten mobilization and formation of secondary minerals in wolframite tailings

Wolframite [(Fe,Mn)WO4] tailings represent a hazardous waste that can pose a threat to the environment, humans, animals and plants. The present study aims to conduct a high-resolution depth profile characterization of wolframite tailings from Wolfram Camp, North Queensland, Australia, to understand the biogeochemical influences on W mobilization. Several indigenous Fe- and S-oxidizing bacteria (e.g., Streptococcus pneumoniae and Thiomonas delicata) in wolframite tailings were found highly associated with W, As, and rare earth elements. Biooxidation of metal sulfides, i.e., pyrite, molybdenite and bismuthinite, produced sulfuric acid, which accelerated the weathering of wolframite, mobilizing tungstate (WO42-). Using synchrotron-based X-ray fluorescence microscopy (XFM) and W L-edge X-ray absorption near-edge spectroscopy (µ-XANES) analysis, wolframite was initially transformed into Na- and Bi- tungstate as well as tungstic acid (partial weathering) followed by the formation of Ga- and Zn- tungstate after extensive weathering, i.e., the wolframite had disappeared. While W (VI) was the major W species in wolframite tailings, minor W(0) and W(II), and trace W(IV) were also detected. The major contaminant in the Wolfram Camp tailings was As. Though wolframite tailings are hazardous waste, the toxicity of W was unclear. Tungsten waste still has industrial value; apart from using them as substitution material for cement and glass production, there is interest in reprocessing W waste for valuable metal recovery. If the environmental benefits are taken into consideration, i.e., preventing the release of toxic metals into surrounding waterways, reprocessing may be economic.

Mercury Reduction, Uptake, and Species Transformation by Freshwater Alga Chlorella vulgaris under Sunlit and Dark Conditions.

As a major entry point of mercury (Hg) to aquatic food webs, algae play an important role in taking up and transforming Hg species in aquatic ecosystems. However, little is known how and to what extent Hg reduction, uptake, and species transformations are mediated by algal cells and their exudates, algal organic matter (AOM), under either sunlit or dark conditions. Here, using Chlorella vulgaris (CV) as one of the most prevalent freshwater model algal species, we show that solar irradiation could enhance the reduction of mercuric Hg(II) to elemental Hg(0) by both CV cells and AOM. AOM reduced more Hg(II) than algal cells themselves due to cell surface adsorption and uptake of Hg(II) inside the cells under solar irradiation. Synchrotron radiation X-ray absorption near-edge spectroscopy (SR-XANES) analyses indicate that sunlight facilitated the transformation of Hg to less bioavailable species, such as β-HgS and Hg-phytochelatins, compared to Hg(Cysteine)2-like species formed in algal cells in the dark. These findings highlight important functional roles and potential mechanisms of algae in Hg reduction and immobilization under varying lighting conditions and how these processes may modulate Hg cycling and bioavailability in the aquatic environment.

X-ray Absorption Near-Edge Spectroscopy Analysis of Indomethacin in Crystalline Forms and in Amorphous Solid Dispersions.

Chlorine K-edge X-ray absorption near-edge spectroscopy (XANES) measurements were performed to characterize the crystal polymorphs of identical active pharmaceutical ingredients (APIs) containing chloride atoms and their amorphous solid dispersions (ASDs). Indomethacin (IMC), of which three crystal forms (α, β, and γ) have been reported, was used as a model API. The shape of XANES spectra was unique to each IMC crystal. The analysis of the crystal structures of IMC revealed that chlorine atoms of the IMCα form had unique intermolecular interactions and halogen bonds with oxygen atoms, while those of the IMCγ form do not have any notable interactions. This result showed that XANES measurements can detect weak interatomic interactions. The shapes of the ASD spectra were clearly different from those of the crystals, suggesting that the environment around the Cl atom of IMC was different from that of the crystals. A thermal stress test was then performed to study the transformation from the amorphous form to the crystalline form of IMC in the ASD. The powder X-ray diffraction (PXRD) patterns indicated that amorphous IMC transformed into crystals during the thermal stress test. In accordance with the PXRD results, the XANES spectra also transformed from ASD to crystalline form. These results indicate that the IMC transformation could be monitored by XANES measurement. Our findings led us to conclude that XANES measurement is a novel approach for the evaluation of crystal polymorphs of APIs and the crystalline state of APIs in ASDs.

Two Types of Single-Atom FeN4 and FeN5 Electrocatalytic Active Centers on N-Doped Carbon Driving High Performance of the SA-Fe-NC Oxygen Reduction Reaction Catalyst

A novel SA-Fe-NC single-atom catalyst is prepared via a spatial isolation strategy. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis indicates that Fe atomically disperses on SA-Fe-NC. Both X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) analyses show that the Fe3+/Fe2+ ratio is 0.3/0.7. Extended X-ray absorption fine structure (EXAFS) fitting presents that the isolated Fe is coordinated with 4.4 N atoms on average, corresponding to the coexistence of Fe–N4 (60%) and Fe–N5 (40%). The SA-Fe-NC electrochemical catalyst presents high ORR activity (Eonset/E1/2 = 1.04/0.88 V vs reversible hydrogen electrode (RHE) and JL = 5.62 mA cm–2), superhigh durability (no obvious loss after 30 000 cycles), and absolute tolerance to methanol in alkaline media. The SA-Fe-NC-based primary Zn–air battery (ZAB) shows a high specific capacity of 806 mAh gZn–1, a high energy density of 1048 Wh kgZn–1, and a high power density of 164 mW cm–2 due to the high electrocatalytic activity of SA-Fe-NC. The ZAB shows a superlong lifetime of 320 h at 10 mA cm–2 resulting from the superhigh stability of the SA-Fe-NC catalyst.

Local Structure and Magnetism of LiFeSi0.01P0.99O4/C as a Cathode Material on Lithium-Ion Battery

The oxidation state and local structure of LiFeSi0.01P0.99O4/C composites as a cathode on lithium-ion battery were investigated by Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The LiFeSi0.01P0.99O4/C sample was prepared by solid-state reaction process. Based on the XANES analysis, the absorption of edge energy (E0) of the sample was 7124.92 eV. In addition, linear combination fitting (LCF) analysis of XANES confirmed the oxidation state of iron mixture of 2+ and 3+ as the effect of silicon doped in LiFePO4. The Fourier Transform (FT) of the Fe K-edge EXAFS fitting analysis showed that the nearest neighbors surrounding atom Fe were the main peak with high intensity that confirmed Fe-O bond; the second and third peak with lower intensity confirmed Fe-P and Fe-Fe bonds, respectively. In addition, the SQUID magnetometer result of LiFeSi0.01P0.99O4/C indicated the antiferromagnetic order temperature of LiFeSi0.01P0.99O4/C at ~51 K with the indication of the presence of impurity and structural distortion.

XANES Study of Tribofilm Formation With Low Phosphorus Additive Mixtures of Phosphonium Ionic Liquid and Borate Ester

The development of low phosphorus engine oils is important to minimize phosphorus-induced exhaust catalyst poisoning and resulting in harmful emissions. In this study, low phosphorus oil formulations were prepared by using an ashless additive mixture of borate ester (SB) with ionic liquid composed of a phosphonium cation and phosphate anion (P_DEHP) at 350 and 700 ppm phosphorus. Tribological properties of this binary additive system were evaluated using a reciprocating cylinder on a flat test configuration. Favorable interaction between P_DEHP and SB resulted in a significant reduction in friction coefficient and wear volume, in particular for P_DEHP(700P) + SB oil blend. Time-scale analysis of tribofilm formation was determined by running the tribological experiments for 5, 15, and 60 min duration. Electrical contact resistance (ECR) results revealed that the addition of P_DEHP at 350 ppm of phosphorus to SB at 500 ppm of boron can reduce the incubation time from 300 to 100 s for stable tribofilm formation. X-ray absorption near-edge spectroscopy (XANES) analysis of tribofilms indicates that the tribofilm mechanism for additive mixtures of P_DEHP and SB initially involves the formation of boron oxide-based films, which later interact with phosphorus to form boron phosphates in addition to iron phosphates. Incorporation of the high amount of boron phosphates in addition to boron oxide/acid and iron phosphates in the tribofilms contributed to the improved tribological performance of P_DEHP(700P) + SB oil. XANES results reveal that tribofilms formed due to the interaction of SB and P_DEHP evolve to a cross-linked structure, wherein the chain length of polyphosphates is increased with the increase in rubbing time.

Fe K-Edge X-ray absorption Near-Edge spectroscopy and morphology analyses of LiFePO4 powders

Two LiFePO 4 powders have been synthesized, i.e. using a natural ironstone and a commercial FeCl 2 ·4H 2 O product as the Fe sources, and their characteristics were compared. The x-ray absorption near-edge spectroscopy (XANES) data, Transmission Electron Microscope (TEM) images and Scanning Electron Microscope (SEM) micrographs were used to examine the value of E 0 and the oxidation number, determine the crystallite sizes, and determine their morphology, respectively. Results showed that the ironstone- and commercial-based LFP powders exhibited E 0 values of 7120.2 and 7119.6 eV respectively which are both almost equal to FeO and indicates that they have an oxidation number of 2 + as expected. In addition, the crystallite size of the ironstone-based LFP was smaller than that of the commercial one. Moreover, the SEM images showed that the natural LFP was more homogeneous than the commercial LFP.

Morphological and electronic properties of titanium dioxide thin film

This paper describes the morphological and X-ray absorption near-edge spectroscopy (XANES) analysis of the titanium dioxide (TiO2) thin film. We fabricated a TiO2 thin film in the laboratory on a clean glass plate using a Physical vapour deposition technique (thermal evaporation method) and characterized. The structural, morphological, and electronic properties of the fabricated samples are presented by X-ray diffraction (XRD), atomic force microscope (AFM), and XANES. It observed from XRD the crystallite size was ∼ 25.66 nm with microstrain ∼ 0.0064 using the W-H plot. The fractal term such as grain size, roughness, kurtosis, and skewness was estimated using AFM. The grain size lies in the nanometric range and found that ∼ 177.21 nm. The electronic properties are studied using XANES. The XANES analysis well supported to XRD measurement and the result found that the fabricated TiO2 thin film was anatase phase.

Abundance of Fe(III) during cultivation affects the microbiologically influenced corrosion (MIC) behaviour of iron reducing bacteria Shewanella putrefaciens

The effect of the presence of Fe(III) during the cultivation on the electrochemical activity and corrosion behaviour of dissimilatory iron reducing bacteria Shewanella putrefaciens was studied by means of ex situ and in situ X-ray absorption near-edge spectroscopy (XANES). Stainless steel AISI 304 and thin iron films were studied as substrates. XANES analysis indicated an accelerated iron dissolution and growth of an oxide/hydroxide film for the culture grown with Fe(III) in comparison to the culture grown in absence of Fe(III). Electrochemical analysis indicated that the biofilm resulted in acceleration of the general corrosion but provides protection against local corrosion.

Ca2+ and SO42− accelerate the reduction of Cr(VI) by Penicillium oxalicum SL2

Some ions in soils may affect the growth and metabolism of microorganisms and subsequently alter the remediation efficiency of Cr(VI). Here, the effects of different Ca2+ and SO42− levels on the reduction of Cr(VI) by Penicillium oxalicum SL2 were investigated. The results showed that Cr(VI) reduction by P. oxalicum SL2 in potato dextrose liquid (PDL) medium was accelerated by the presence of exogenous Ca2+ and SO42−. The Cr(VI) reduction rates were increased by 52.5% (200 mg L−1 Ca2+ treated) and 55.9% (2000 mg L−1 SO42− treated), respectively. High concentration of Ca2+ in medium resulted in the production of calcium oxalate crystals, which was contributed to the adsorption of chromium. In addition, X-ray absorption near-edge spectroscopy (XANES) analysis showed that P. oxalicum SL2 could reduce the toxicity of Cr(VI) by synthesizing cysteine (Cys) and reduced glutathione (GSH). The decrease of thiol compounds (Cys and GSH) in P. oxalicum SL2 mycelia treated with SO42− proved the alleviation of oxidative stress. In conclusion, exogenous Ca2+ could reduce the damage of Cr(VI) to P. oxalicum SL2 by maintaining the integrity of cell wall, and the addition of SO42− alleviated the Cr(VI) toxicity to P. oxalicum SL2, thus accelerating the reduction of Cr(VI).

XANES analysis and structural properties of CdS-doped TiO2

The present paper reports on fabrication of the undoped and cadmium sulphide (CdS) doped titanium dioxide (TiO2) samples (1 wt% CdS-TiO2 and 2 wt% CdS-TiO2) and their characterization. Effect of the dopant on microstructural, optical and electronic properties of the fabricated samples are presented by X-ray diffraction (XRD), atomic force microscope (AFM), Raman spectra, UV–visible absorption spectra and X-ray absorption near edge spectroscopy (XANES). XANES spectra of the Ti L edges and O K edges of the CdS-TiO2 films revealed that with 2 wt% CdS doping in theTiO2, crystal structure changes from the anatase type to the rutile type. Ti L edges as well as O K edges both exhibits that 2 wt% CdS doping in TiO2 has modified the electronic structure of TiO2. Results of XRD and AFM show that crystallite size and roughness of the TiO2 significantly reduces with the CdS doping. It is observed from Raman spectra that the peaks shift towards higher wave number with increasing CdS contents indicating decrease in bond lengths. Optical band-gap for the undoped TiO2 is 3.33 eV and 2.71eV with 2 wt% CdS doped and it is found that absorption band-gap of TiO2 is red shifted to visible region.

Molybdenum isotope fractionation between Mo4+ and Mo6+ in silicate liquid and metallic Mo

Previous work has shown that Mo isotopes measurably fractionate between metal and silicate liquids, even at temperatures appropriate for core formation. However, the effect of variations in the structural environment of Mo in the silicate liquid, especially as a function of valence state, on Mo isotope fractionation remained poorly explored. We have investigated the role of valence state in metal-silicate experiments in a gas-controlled furnace at 1400 °C and at oxygen fugacities between 10−12.7 and 10–9.9, i.e. between three and 0.2 log units below the iron-wüstite buffer. Two sets of experiments were performed, both with a silicate liquid in the CaO-Al2O3-SiO2 system. One set used molybdenum metal wire loops as the metal source, the other liquid gold alloyed with 2.5 wt% Mo contained in silica glass tubes. X-ray absorption near-edge spectroscopy analysis indicates that Mo6+/ΣMo in the silicate glasses varies between 0.24 and 0.77 at oxygen fugacities of 10–12.0 and 10–9.9 in the wire loop experiments and between 0.15 and 0.48 at 10–11.4 and 10–9.9 in the experiments with Au-Mo alloys. Double-spiked analysis of Mo isotope compositions furthermore shows that Mo isotope fractionation between metal and silicate is a linear function of Mo6+/ΣMo in the silicate glasses, with a difference of 0.51‰ in 98Mo/95Mo between purely Mo4+-bearing and purely Mo6+-bearing silicate liquid. The former is octahedrally and the latter tetrahedrally coordinated. Our study implies that previous experimental work contained a mixture of Mo4+ and Mo6+ species in the silicate liquid. Our refined parameterisation for Mo isotope fractionation between metal and silicate can be described asΔ98/95Mometal–silicate=−1.43±0.14×106Mo6+/ΣMo+8±6×104T2Molybdenum isotope ratios therefore have potential as a proxy to constrain the oxygen fugacity during core formation on planetary bodies if the parameterisation of Mo6+/ΣMo variation with oxygen fugacity is expanded, for instance to include iron-bearing systems. On Earth literature data indicate that the upper mantle is depleted in heavy Mo isotopes relative to the bulk Earth, as represented by chondrites. As previously highlighted, this difference is most likely not caused by core formation, which either enriches the mantle in heavy Mo isotopes or causes no significant fractionation, depending on temperature and, as we determined here, Mo6+ content. We reaffirm that core formation does not account for the Mo isotope composition of the modern upper mantle, which may instead reflect the effect of fractionation during subduction as part of global plate recycling.

Operando Studies Reveal Structural Evolution with Electrochemical Cycling in Li–CoS2

The drive toward high energy density alternatives to Li-ion batteries has led to great interest in energy storage materials not inherently constrained by the capacity limits of the currently employed intercalation electrode materials. Among the alternatives under consideration are electrode materials with theoretical capacities many times greater than intercalation electrodes that store charge through so-called conversion reactions. However, the significant structural changes that enable the high theoretical capacity of conversion systems contribute to issues of poor efficiency and short cycle life. To better understand cycling issues in conversion systems, we study the local structure evolution of CoS2 during Li storage. Being metallic and potentially capable of redox on both anion and cation sites, CoS2 would be expected to display promise as a cathode material. Through combined ex situ X-ray absorption near-edge spectroscopy and pair distribution function analysis from operando X-ray total scattering, ...

Investigating the local structure of B-site cations in (1-x)BaTiO3–xBiScO3 and (1-x)PbTiO3–xBiScO3 using X-ray absorption spectroscopy

The structural properties of (1-x)BaTiO3–xBiScO3 and (1-x)PbTiO3–xBiScO3 were investigated using powder X-ray diffraction and X-ray absorption spectroscopy. Diffraction measurements confirmed that substituting small amounts of BiScO3 into BaTiO3 initially stabilizes a cubic phase at x = 0.2 before impurity phases begin to form at x = 0.5. BiScO3 substitution also resulted in noticeable changes in the local coordination environment of Ti4+. X-ray absorption near-edge spectroscopy (XANES) analysis showed that replacing Ti4+ with Sc3+ results in an increase in the off-centre displacement of Ti4+ cations. Surprisingly, BiScO3 substitution has no effect on the displacement of the Ti4+ cation in the (1-x)PbTiO3–xBiScO3 solid solution.

Fe K-Edge X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) analyses of LiFePO4 and its base materials

XANES analysis has been performed with the aim of knowing the Fe oxidation state in a synthesized LiFePO4 and its base materials. XANES measurements were performed at SLRI on energy around Fe K-edge. An XRD analysis has also been performed with the aim of knowing the phase composition, lattice parameters and crystallite size of the LiFePO4 as well as the base materials. From the XRD analysis, it was found that the dominating phase in the iron sand sample was Fe3O4 and the only phase found after calcination was LiFePO4. The latter phase exhibited crystallite size of 100 nm and lattice parameters a = 10.169916 Å, b = 5.919674 Å, c = 4.627893 Å. Qualitative analysis of XANES data revealed that the oxidation number of Fe in the sample before calcination was greater than that after calcination and Fe in the natural iron sand, indicated by the E0 values of 7129.2 eV, 7120.6 eV and 7124.4 eV respectively.