The application of synchrotron X-ray techniques to the study of rechargeable batteries

The increased use of rechargeable batteries in portable electronic devices and the continuous development of novel applications(e.g. transportation and large scale energy storage), have raised a strong demand for high performance batteries with increased energy density, cycle and calendar life, safety and lower costs. This triggers significant efforts to reveal the fundamental mechanism determining battery performance with the use of advanced analytical techniques. However, the inherently complex characteristics of battery systems make the mechanism analysis sophisticated and difficult. Synchrotron radiation is an advanced collimated light source with high intensity and tunable energies. It has particular advantages in electronic structure and geometric structure(both the short-range and long-range structure)analysis of materials on different length and time scales. In the past decades, synchrotron X-ray techniques have been widely used to understand the fundamental mechanism and guide the technological optimization of batteries. In particular, in situ and operando techniques with high spatial and temporal resolution, enable the nondestructive, real time dynamic investigation of the electrochemical reaction,and lead to significant deep insights into the battery operation mechanism.This review gives a brief introduction of the application of synchrotron X-ray techniques to the investigation of battery systems. The five widely implicated techniques, including X-ray diffraction(XRD), Pair Distribution Function(PDF), Hard and Soft X-ray absorption spectroscopy(XAS) and X-ray photoelectron spectroscopy(XPS) will be reviewed, with the emphasis on their in situ studies of battery systems during cycling.     

A comparative study of EDTA-gel derived BSCCO and Pb-BSCCO systems by thermoanalytical and X-ray diffraction techniques

Summary This paper deals with the first investigation concerning the thermal behaviour of Ni(II) complexes with ligands having biguanide moieties. The new complex [NiL(1)](ClO₄)₂·2.5H₂O (1) with the Schiff base resulted in [2+1] condensation of N,N-dimethylbiguanide with pentane-2,4-dione (L(1)) and the complex [Ni₂L(2)](ClO₄)₄ (2), with the Schiff base, L(2), resulted through the oxidative condensation of L(1) have been synthesized and characterised. The bonding and stereochemistry of the complexes have been characterized by IR and electronic spectra. The cyclic voltammograms show the characteristic waves for mononuclear and respectively binuclear Ni(II) complexes and indicate that both complexes exhibit catalytic effects on the CO₂ electrochemical reduction. The thermal behaviour provided confirmation of the complexes composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands generates a different thermal behaviour for complexes.     

Characterization of snake skin by thermoanalytical techniques

Snake skin is a viable and readily available material as a model for human skin. Pharmaceutical applications use shed snake skin to study the effects of sunscreens on exposure to UV radiation (e.g. benzophenone on Boa integument). In order to understand the effects of radiation or drug transport through this model skin, one must determine its basic physical properties. This preliminary study evaluated two types of snake skin, namely Cuban Boa a 'dark' skin (Epicrates angulifer) and Green tree python a 'light' skin (Morelia viridis). Previous studies by other investigators have used pig, rabbit and snake skin as a human skin substitute. The structure of both snake skins was comparable based on IR spectroscopy and were functionally amino acids and moisture. Photomicrography by light and scanning electron microscopy revealed strong anatomic similarities. Morphologically there were two structures visible, namely a cellular and hinge-fibrous area. The thermal techniques indicated a phase transition at 35-75°C, which is associated with lipid melting. There was an 8 and 12% mass loss for the light skin and dark skin, respectively, which is interpreted, in part, as moisture loss at <100°C. The physical and analytical properties establish a base line that will be used in the future to differentiate various sunscreen types, such as benzophenone and octyl salicylate. Study was also done to determine the effect of an application of a commercially available sunscreen using SEM.This revised version was published online in November 2005 with corrections to the Cover Date.     

Analytical and mineralogical studies of ore and impurities from a chromite mineral using X-ray analysis, electrochemical and microscopy techniques

A wide analytical study of South African chromite ore, material with high interest in ceramic industry, has been carried out. With this purpose, an accurate chemical identification and mineralogical characterization of the mineral and the gangue have been performed using X-ray fluorescence (XRF), voltammetry, X-ray diffraction (XRD), light microscopy (LM), and scanning electron microscopy (SEM/EDX). The elemental composition of the sample (ore and gangue) has been obtained by XRF. The voltammetric analysis has allowed to demonstrate that iron in the sample was as Fe(II). The main compound of the chromite ore was a spinel (magnesiochromite ferroan), identified by XRD from the sample, which constitutes the chromite ore. This technique has also been useful to characterize some silicates as impurities in the chromite ore sample. Light microscopy has allowed the detection of the spinel and the identification of a silicate impurity (chrome chlorite), by means of their colouration. On the other hand, the other silicate impurity was identified as labradorite by means of X-ray microscopy by SEM/EDX. Finally, a strategy was developed to calculate the composition of each mineral in the unknown sample. The obtained results were: chromite spinel 82.89%, chlorite 12.79% and labradorite 4.32%.     

The application of thermoanalytical methods in the investigation of biological substances

The equilibria and thermodynamics of a number of naturally occuring isolated compounds (e.g. proteins, amino acids, carbohydrates) have recently been studied in several laboraties in different temperature ranges, and thermoanalytical methods have been used to study structural changes of biological materials, among them human tissues.In our investigations we succeeded in appling the derivatograph for the assay of glycosaminoglycans and for the characterization of the stability of crosslinked proteins in intact human and animal tissues. By means of this method age-related and pathological changes and repair reactions were studied in various connective and vascular tissues.Other temperature-dependent techniques (DSC, polarizing microscopy) were used successfully in another series of experiments. Alterations in the characteristic order-disorder transition temperatures of human serum lipoproteins could be demonstrated in pathological conditions; the altered physical structure of lipoproteins might give an additional explanation to the assumed mechanism of different metabolic disorders.

---

Zusammenfassung Die Gleichgewichte und die Thermodynamik einer Reihe von natürlich vorkommenden isolierten Verbindungen (z. B. Proteine, Aminosäuren, Kohlenhydrate) wurden in verschiedenen Laboratorien in verschiedenen Temperaturbereichen untersucht. Hierbei wurden thermoanalytische Methoden zum Studium der Strukturänderungen von biologischem Material, u. a. von menschlichem Gewebe, eingesetzt.In unseren Untersuchungen gelang es den Derivatographen zur Prüfung von Glycosaminoglycanen und zur Charakterisierung der Stabilität quervernetzter Proteine in intakten menschlichen und tierischen Geweben einzusetzen. Durch diese Methode wurden altersbedingte und pathologische Änderungen sowie Reaktionen zur Wiederherstellung in verschiedenen Binde und Vasculärgeweben studiert.Andere temperaturabhängige Techniken (DSC, Polarisationsmikroskopie) wurden in anderen Versuchsserien mit Erfolg eingesetzt.

---

, . , , , , . . , . .

---

---

Plenary lecture     

The application of thermoanalytical methods for the characterization of zeolite catalysts

Through the coupling of a DSC 111 (Setaram) with a gas dosing valve and a catharometer detector, equipment was developed for the investigation of adsorbents and catalysts. This equipment was applied for the determination of differential and integral heats of adsorption of C₂ to C₄ hydrocarbons on zeolites of the pentasile family. The proposed method has sufficient accuracy for the determination of adsorption heats for technical products. The advantages and the problems of the presented method are discussed.

---

Zusammenfassung Durch Kombination eines DSC-Geräts (Setaram Typ 111) mit einem Gasdosierventil und einem Wärmeleitfähigkeitsdetektor wurde ein Gerät für die Untersuchung von Adsorbentien und Katalysatoren geschaffen. Dieses Gerät wurde zur Bestimmung difierentieller und integraler Adsorptionswärmen von C₂- bis C₄-Kohlenwasserstoffen an Zeolithen der Pentasil-Familie eingesetzt. Die vorgeschlagene Methode ist ausreichend genau, um Adsorptionswärmen technischer Produkte zu bestimmen. Vorzüge und Probleme der Methode werden diskutiert.

---

111 () - - , . C₂ C₄ . . .

     

Characterisation of aerosol particles using combined thermoanalytical techniques

Four different artificial aerosol particles as well as one standard environmental aerosol particle (NIST SRM 1649a) were investigated. While the mass loss of the aerosol particles varies from 1.5 to 32% of the entire mass, only a small part of each volatile fraction consists of organic compounds. Due to the construction of the combined thermoanalytical system, only a small part of the evolved gases is used for the mass spectrometric investigation. This results in a restricted sensitivity which does not allow an identification of individual organic components. Additional investigations like thermal desorption GC-MS reveal up to 1600 individual components (SRM 1649a). This revised version was published online in July 2006 with corrections to the Cover Date.     

The application of artificial neural networks for the selection of key thermoanalytical parameters in medicinal plants analysis

In the present study three thermoanalytical methods: differential thermal analysis (DTA), thermogravimetric analysis (TGA), and derivative thermogravimetric analysis (DTG) were used to investigate the thermal behavior of medicinal plant raw materials. In order to describe DTA curve, designation of the onset T(i), and peak T(p), temperatures was required. In TGA the mass losses Delta(m), and in DTG the temperature range of peak DeltaT, peak temperature T(p), and peak height h, were recorded. All parameters were read for three stages of the thermal decomposition of plant samples which resulted in obtaining eighteen thermal variables for each sample. Some similarities in the course of thermal decomposition of the same plant organs were recognized, but complexity of the obtained data made it very difficult to determine if they could differentiate between medicinal plant materials and which of them encode the most valuable information about the studied herbals. In order to confirm the existence of any relations between the chemical composition of medicinal plants and their thermal decomposition and to find out which thermoanalytical variables or decomposition stages can be considered as the most significant in terms of their evaluation, it was decided to apply fully connected feed-forward artificial neural networks (ANN). Two different training algorithms were used to address the problem: back-propagation of error and conjugate gradient descent. To verify the results two-dimensional (2-D) Kohonen self-organizing feature maps (SOFMs) were employed. Two alternative datasets of thirteen key variables discriminating plant samples have been proposed.     

Studies on crosslinking of EPDM-PE blends by thermoanalytical techniques

The effect of blend ratio and peroxide concentration on crosslinking characteristics of EPDM-PE blends were studied by Differential Scanning Calorimetry, Brabender plasticorder and Rheometer. Crosslinking of EPDM-PE blends follows first order reaction kinetics. The curing exotherm increases but activation energy decreases with increase in EPDM content in the blends. The same however increases with the increase in concentration of DCP upto a certain level, while the activation energy is almost independent of peroxide concentration. The cure rate increases whereas optimum cure time and energy consumption for curing decrease with increase in the EPDM-PE ratio. A method for determination of crosslinking efficiency in the case of blend systems was developed from high temperature modulus to predict the properties and the curing behaviour of the blends.

---

Zusammenfassung Mittels DSC, Brabender Plasticorder und Rheometer wurde der Einfluß von Mischungsverhältnis und Peroxidkonzentration auf den Vernetzungsverlauf von EPDM-PE-Gemischen untersucht. Die Vernetzung von EPDM-PE-Gemischen verläuft nach einer Reaktion erster Ordnung. Je höher der Anteil von EPDM im Gemisch, um so exothermer ist die Vernetzung und um so kleiner ist die dazugehörige Aktivierungsenergie. Mit dem Anwachsen der DCP-Konzentration bis zu einem gewissen Niveau wächst der exotherme Charakter, während die Aktivierungsenergie fast unabhängig von der Peroxidkonzentration ist. Mit dem Anstieg des EPDM/PE-Verhältnisses wächst die vernetzungsgeschwindigkeit, während die optimale Vernetzungszeit und der Energieverbrauch für die Vernetzung sinken. Es wurde ein Verfahren zur Bestimmung der Vernetzungseffizienz bei Mischsystemen entwickelt, um Eigenschaften und Vernetzungsverhalten von Gemischen voraussagen zu können.

     

The application of thermoanalytical methods in studies on the pathomechanism of human diseases

This mini-review attempts to give a short summary of the application of temperature-dependent techniques in bio-medical research. Results obtained by thermal analysis provide valuable support to scientific theories on various human pathophysiological processes as well as to several therapeutic approaches. Special attention is focussed on cardiovascular disease, since of approx. 11 million deaths occurring per annum in developed countries more than 3.9 million were due to this disease, as recorded by WHO. Recent research on the pathogenesis of atherosclerosis has concentrated on the physico-chemical nature of the arteries and on the roles of serum lipoproteins and defects in cellular metabolism of cholesterol. An understanding of the physical and chemical nature of lipids accumulated in the arterial wall may help explain how it gets into the artery and how it can be removed. Smectic cholesteryl-ester phases had been observed in a number of fatty streaks and advanced atherosclerotic lesions within the arteries. These phases have physical characteristics that can be identified with the polarizing or electron microscope, by calorimetry, by NMR spectrometry or by X-ray diffraction.

---

Zusammenfassung Es wird versucht, einen kurzen überblick über die Anwendung temperaturabhängiger Techniken in der biomedizinischen Forschung zu geben. Thermoanalyti-sche Ergebnisse bieten eine wertvollen Beitrag für wissenschaftliche Theorien zu verschiedenen pathophysiologischen Vorgängen beim Menschen als auch für verschiedene therapeutische Methoden. Besondere Aufmerksamkeit wird Herzkreislaufkrankheiten geschenkt, da laut WHO-Berichten von den jährlich etwa 11 Millionen Todesfällen in den hochentwickelten Ländern mehr als 3,9 Millionen auf diese Krankheiten zurückzuführen sind. Die jüngste Forschung auf dem Gebiete der Pathogenese von Atherosklerose konzentrierte sich auf die physikalisch-chemische Natur der Arterien sowie auf die Rolle von Serumlipoproteinen und Defekte im Zellmetabolismus von Cholesterol. Eine eingehende Untersuchung der physikalischen und chemischen Natur von den in der Arterienwand angehäuften Lipiden kann helfen zu erklären, wie diese in die Arterie gelangen und wie sie von dort entfernt werden können. In einer Anzahl von fettigen Bändern und krankhaften atherosklerotischen Veränderungen im fortgeschrittenen Stadium in den Arterien wurden smektische Cholesterylesterphasen beobachtet. Diese Phasen besitzen physikalische Eigenschaften, die mittels Polarisations- oder Elektronenmikroskop, Kalorimetrie, NMR-Spektroskopie und Röntgendiffraktion identifiziert werden können.

     

Stability and compatibility study on enalapril maleate using thermoanalytical techniques

This paper demonstrates the application of thermal analysis in compatibility and stability studies between an ACE inhibitor (enalapril maleate) and excipients. The results have helped to elucidate the reason of a stability problem observed during the storage of enalapril maleate tablets. Incompatibility between enalapril maleate and colloidal silicon dioxide was detected. Besides, it was confirmed that the reaction between enalapril maleate and NaHCO₃ increases the thermal stability of the drug. This study supports the importance of using thermoanalytical methods in the development of pharmaceuticals.     

Study of urea intercalation into halloysite by thermoanalytical and spectroscopic techniques

Intercalation of a kaolinite-containing halloysite from Biela Hora (Slovakia) with urea was investigated by simultaneous TG–DTA, XRD, FTIR (DRIFT), and Raman spectroscopy. The process of intercalation and thermal deintercalation was followed for the as-prepared and the washed (with isopropanol) samples. The proposed structural model was supported by molecular mechanical calculations. Incorporation of the intercalate (in 5 wt%) in molten polypropylene at 200 °C resulted in the complete delamination of the mineral. It is supposed that gas formation as a result of urea decomposition between the layers prevents reorientation and restructuring of the layers.     

A thermoanalytical assessment of an organoclay

High resolution thermogravimetric analysis (TG) has attracted much attention in the synthesis of organoclays and its applications. In this study, organoclays were synthesised through ion exchange of a single cationic surfactant for sodium ions, and characterised by methods including X-ray diffraction (XRD) and TG. The changes of surface properties in montmorillonite (MMT) and organoclays intercalated with surfactant were determined using XRD through the changes in the basal spacing. The TG was applied in this study to investigate more information of the configuration and structural changes in the organoclays with thermal decomposition. There are four different decompositions steps in differential thermogravimetric curves. The obtained TG steps are relevant to the arrangement of the surfactant molecules intercalated in MMT and the thermal analysis indicates the thermal stability of surfactant modified clays. This investigation provides new insights into the properties of organoclays and is important in the synthesis and processing of organoclays for environmental applications.     

Application of combined thermoanalytical techniques in the investigation of cyclodextrin inclusion complexes

Citronellol and citronellyl acetate have been entrapped with α-, β- and γ-cyclodextrin (CD). Evolved gas detection and TG-MS coupling was applied to prove the actual inclusion complex formation between monoterpens and CDs. The terpene content was determined by UV-VIS specrophotometry and RP-HPLC and the effect of storage time on the terpene content was also investigated. The α- and γ-cyclodextrin inclusion complexes showed higher thermal stabilities vs. dynamic heating compared to the β-CD complexes. On the contray, the retention of guest using β-cyclodextrin even after 10 years of storage was much more pronounced. Experimental data other than 1:1 complex compositions are assumed. Molecular modeling experiments also suggested multiple complex compositions.     

Statistical analysis of thermoanalytical experimental data

A statistical technique based on the Wilcockson criterion is suggested for estimation of the reproducibility of thermoanalytical experiments. Reduction of the whole physicochemical process to a quasi-one-stage process is described.This work was carried out partially with the aid of International Science Foundation (Programme Students and Post-Graduate Students).     

The application of long wavelength radiation in X-ray analysis

The authors used long wavelength X-ray radiation excited by low energy electrons for analytical purposes. Low energy electron excitation was achieved with an open window tube. The authors used a type that was developed in Philips laboratories. The electron source was a glow discharge from which the electrons ( 15 keV) are extracted and directed towards the anode. A photon spectrum of “Bremsstrahlung” and characteristic peaks is generated at a gold anode. In addition about half of the impinging electrons is reflected and may, thanks to the open window, be used to irradiate a specimen in spite of a partial loss of energy due to the collisions.The authors mention the following attractive characteristics: the tube is simple to operate and may easily be exchanged for a closed tube; no high vacuum is needed, a feature which, however, at the same time inhibits the determination of traces of O, N, C; about 7 cm² of the specimen, which may be an insulator, is irradiated. A discussion of applications illustrates the usefulness of the tube.     

Study of purification process of single-walled carbon nanotubes by thermoanalytical techniques

The thermal behaviour of commercial Carbolex single-walled carbon nanotubes (SWCNTs) both as-received and after purification by a novel method has been studied by thermogravimetric/derivative thermogravimetric/difference thermal analysis (TG/DTG/DTA). Purification from metal catalysts (Ni and Y) has been successfully obtained using 0.1 M I₂ in iso-propanol instead of the usual concentrated HNO₃. The final residues of thermal analysis have been characterised by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The gathered results showed that the as-received SWCNTs burns out in a one-step between 573 and 923 K, whereas the SWCNTs treated with HNO₃ become highly hygroscopic. The I₂-iso-propanol-treated SWCNTs showed three overlapped exothermic peaks between 500 and 973 K in the DTA curve, which allowed separating amorphous carbon from SWCNTs by air-thermal treatment at 573 K. The graphite-like compounds, which are present in both untreated and treated SWCNTs, does not burn up to 1173 K.     

The determination of Eu and Sm by application of X-ray spectrometry to isotope-source activation analysis

The use, for analysis, of K X-rays proceeding from metastable and beta-emitting radionuclides—produced by neutron activation—is an undeveloped aspect of activation analysis. Consequently, this study examines the feasibility of applying X-ray spectrometry to isotope source activation analysis and in particular the determination of Sm and Eu at low levels is described. Generally speaking, the sensitivity is seriously restricted by the thermal neutron flux of the source but in certain specific cases the analysis is favoured by the nuclear properties of the elements concerned. Therefore, the selection of elements was based largely on their demand for analysis and their ability to produce a practicable yield. Optimum signalto-noise ratios were attained by employing a detector that was particularly sensitive at energies below 150 keV. Analytical conditions are demonstrated for the elements of interest over a wide range of concentrations in small samples, and ultimately the applicability of the method was tested by the analysis of a typical monazite sample. The analytical potential of the method is thoroughly appraised and possible practical applications are discussed.     

Characterization of Lippia sidoides oil extract-b-cyclodextrin complexes using combined thermoanalytical techniques

Thermoanalytical techniques, being rapid and un-expensive have been used for the investigation of the cyclodextrin inclusion complexes for three decades. The conventional thermoanalytical techniques (TG and DTA/DSC) follow the thermal properties of the uncomplexed compounds. Consequently, the inclusion complex formation as well as the liberation of the entrapped guest cannot be followed. Monitoring the products of the thermal fragmentation of parent cyclodextrin and the included molecule(s), applying TG-MS combined technique provides evidence concerning the inclusion complex formation, and besides, gives selective signal to follow the decomposition of the cyclodextrin inclusion complexes. b-cyclodextrin inclusion complexes of Thymol and Lippia sidoides Cham essential oil extract have been prepared and investigated using conventional and combined (TG-MS) thermoanalytical techniques. The evolved gas analysis proved the inclusion complex formation between the host and guests. By the evaluation of the experimental results the elaboration of the entrapped guests from the cyclodextrin cavity could be followed. This revised version was published online in July 2006 with corrections to the Cover Date.