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The dynamics of a C60 fullerene located near the axis of rotation of a fullerite fragment of consisting of 63 fullerenes forming a face-centered cubic lattice has been studied numerically. The achiral molecule C60 under consideration has the highest symmetry in the fullerene family and is mathematically modeled as a discrete covalent molecule or as a spherical particle. This molecule rotates around its center of mass in a fullerite crystal with a frequency of about 100 GHz. Numerical study of C60 molecular rotators located in rotating reference frames was carried out using molecular dynamics methods, a hybrid discrete–continuous mathematical model, the Euler approach and the fourth order Runge–Kutta method for numerical solution of differential equations. A parametric study of the influence of the direction and frequency of rotation of a molecular cluster (up to 1 GHz) on the reorientation time and rotational dynamics of the fullerene molecule was carried out in the picosecond range (up to 10 ps). Chiral phenomena in the C60 molecular crystal and the logarithmic dependence of the reorientation time of C60 fullerene on the rotation period of the fullerite were discovered based on the results of numerical calculations. [ABSTRACT FROM AUTHOR]

The surface morphology, elemental and phase compositions, and local electrical properties of fullerite films containing various atomic fractions of tin and bismuth have been studied using scanning probe microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and Fourier transform IR spectroscopy. The films were grown on oxidized single-crystal silicon substrates by deposition from a combined atomic–molecular flow using resistive evaporation in vacuum. Their thickness was 1 μm. The as-grown films consisted of grains ranging in size from 30 to 200 nm. Their X-ray diffraction patterns showed reflections from C60 fullerite with a face-centered cubic lattice, which was in a stressed state due to the incorporation of dopant atoms, and reflections from pure tin and bismuth. Optical spectroscopy results indicated the formation of complexes of fullerenes with Sn and Bi atoms. According to electric force microscopy results, the tin- and bismuth-doped fullerite films have a considerably lower surface potential and a nonuniform surface capacitance gradient distribution. [ABSTRACT FROM AUTHOR]

The effect of the action of temperature on the structure and phase composition of an Fe3C/Fe7C3/P-phase/Cam composite obtained by mechanosynthesis of Fe–75 at % C has been studied by the methods of X‑ray diffraction, Mössbauer spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. It is shown that the structural and phase changes at heating have a multistage character. In the temperature range 315–400°C crystallization of the paramagnetic P-phase with generation of Fe3C and/or Fe7C3 occur. In the course of heating to higher temperatures, complete decomposition of carbide Fe7C3 (in the range 450–550°C) and partial decomposition of Fe3C (at 600°C and above) are observed. After cooling from 800–1000°C the mechanocomposite consists of α-Fe, cementite Fe3C, and graphite. The phase transformations are accompanied by the processes of composite oxidation with the formation of Fe3O4 oxide and its subsequent reduction. The P-phase is a disorded amorphous carbide Fe1 – xCx, which is characterized by magnetic ordering at the temperature of liquid nitrogen. [ABSTRACT FROM AUTHOR]

The fullerene family, whose most popular members are the spherical C 60 and C 70 molecules, has recently added a new member, the cube-shaped carbon molecule C 8 called a cubene. A molecular crystal based on fullerenes is called fullerite. In this work, based on relaxational molecular dynamics, two fullerites based on cubenes are described for the first time, one of which belongs to the cubic system, and the other to the triclinic system. Potential energy per atom, elastic constants, and mechanical stress components are calculated as functions of lattice strain. It has been established that the cubic cubene crystal is metastable, while the triclinic crystal is presumably the crystalline phase in the ground state (the potential energies per atom for these two structures are −0.0452 and −0.0480 eV, respectively).The cubic phase has a lower density than the monoclinic one (volumes per cubene are 101 and 97.7 Å 3 ). The elastic constants for the monoclinic phase are approximately 4% higher than those for the cubic phase. The presented results are the first step in studying the physical and mechanical properties of C 8 fullerite, which may have potential for hydrogen storage and other applications. In the future, the influence of temperature on the properties of cubenes will be analyzed. [ABSTRACT FROM AUTHOR]

In this work, through the technology of producing endohedral metallofullerene in macroscopic quantities, the process of pressure polymerization of Sc 2 C 2 @C 82 and their mechanical properties have been investigated in detail using a set of experimental and theoretical methods. The crucial role of endohedral atoms is demonstrated by comparison with pristine fullerenes. It is shown that the embedding of Sc 2 C 2 complex inside a fullerene significantly facilitates the polymerization process which finally leads to the highly rigid material at high pressures. [Display omitted] [ABSTRACT FROM AUTHOR]

Comparative studies of contact interactions of Fe, Ni, Cu melts with graphite and fullerite were performed using a sessile drop method, X-ray analysis and metallographic analysis. It was shown that the contact interaction of Fe with fullerite and graphite substrates caused changes in the structure of iron. Namely, perlite, cementite and graphite precipitates in different proportions were formed. In comparison with Fe, in case of Ni total soaking of the fullerite substrate by the metal (and only partial in case of graphite) was observed while metal structure remained unchanged. No contact interaction of Cu with fullerite and graphite occurred. The differences in wetting of carbon materials by metal melts were stated to be caused by the structural changes in fullerite at heating higher than 1000оC (its amorphization) and further increase of carbon substrate porosity. A scheme was presented illustrating the difference in contact interactions of metal melts with fullerite and graphite.

3Ti–Si–2C composite materials are obtained by self-propagating high-temperature synthesis using various structural forms of carbon (carbon black, carbon nanotubes, fullerite). The phase composition of the samples is studied by X-ray diffraction. The amount of the MAX phase Ti3SiC2 (Mn+ 1AXn phase where n = 1, 2, 3, ...; M is a transition d metal; A is a p element; and X is carbon) in the obtained materials depends on the form of carbon. The formation of TiC carbide is found in the sample with carbon black, and TiC and Ti5Si3Cx are found in the samples with carbon nanotubes and fullerite. All samples contained traces of the TiSi2 phase. Scanning electron microscopy shows that the structure of the samples with fullerite and nanotubes is inhomogeneous and contains regions simultaneously composed of several phases. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigating the thermal destruction of fullerite and subsequent carbon ordering with the formation of graphite (graphitation) upon heating the samples to 1700°C. We study C60/70 fullerite powders with a predominant C60 content (C60—82.18%, C70—14.08%) obtained by the electric-arc evaporation of graphite rods with subsequent fullerene extraction from fullerene-containing soot by boiling toluene. Heating is performed in a CO environment. We investigate the changes in the fullerite crystal structure after thermal impact by means of X-ray diffraction, analyze the change in the spatial orientation in the carbon-carbon bonds by Raman spectroscopy, and estimated the particle dispersion by scanning electron microscopy. We show that the structural changes in the C60/70 fullerite upon heating above 950°C are caused by the destruction of its crystal structure with amorphous fullerite-like phase formation. Amorphization is accompanied by an increase in the dispersion of the carbon powders. Subsequent structural ordering is observed upon heating to temperatures above 1500°C and is accompanied by the formation of a graphite-like amorphous phase. Detailed analysis of the fullerite structure after its amorphization is performed on the samples annealed at 1600°C for 0.5–16 h. We find that after heating to 1600°C, the sample consists of, predominantly, turbostratic carbon; we also record α graphite and β graphite with the low degree of ordering. Ordering with graphite formation is shown to be accompanied by carbon-particle coarsening. [ABSTRACT FROM AUTHOR]

Comparative studies of the iron–75fullerite and iron–75graphite composites obtained by the mechanosynthesis method have been performed by X-ray diffraction and Mössbauer spectroscopy. It has been shown that a carbon polymorph and its deformation stability predetermine the kinetics of formation for the phase composition of composites. In the case of disordering in the crystal structure of fullerite with the further destruction of fullerene molecules, iron–75fullerite powders are characterized by the same phase composition as for the iron–75graphite composite: amorphous carbon, Fe3C, Fe7C3, and the P-phase. [ABSTRACT FROM AUTHOR]

In the present paper, an attempt has been made for the comparative study of different equations of state and investigated the thermodynamic and thermoelastic properties for C60 crystalline solid. We have fitted the experimental compression curve to the modified Tait's equation of state. Using the best fit values of B0 and B0′, we have computed the compression behavior of C60 crystalline solid in the face-centered-cubic structure in the pressure range of 0–11 GPa at room temperature. Tait's EOS has further extended to analyze the temperature dependence of thermal expansivity and bulk modulus for C60 crystalline solid. We have attempted for theoretical prediction of pressure-dependent Grüneisen parameter and isothermal bulk modulus for C60 crystalline solid at reference temperature. The calculated values of thermal expansion are in good agreement with the available theoretical and experimental results, which reveals the validity of present work. The results of the coefficient of thermal expansion achieved in the present study are found to display good agreement with other available results. The present relationship of thermal expansivity may be used to understand the temperature behavior of nanomaterials. [ABSTRACT FROM AUTHOR]

A hybrid discrete-continuous physical and mathematical model is used to study what deformation characteristics cause the rolling effect of C60 fullerene in a fullerite crystal. The interaction of fullerene atoms with surrounding molecules is described using a centrally symmetric interaction potential, in which the surrounding molecules are considered as a spherical surface of uniformly distributed carbon atoms. The rotational motion of fullerene is described by the Euler dynamic equations. The results of a numerical study of the influence of the rate, magnitude, and direction of strain on the dynamic characteristics of the rotational and translational motion of C60 fullerene in a crystalline fragment are presented.

Dynamics of charged fullerene in a surface layer of fullerite is studied under the influence of neutral or charged particles of the gas phase surrounding the fullerite material. The translational displacements of the nodes of the crystal lattice structure are determined by the equations of motion of the centers of mass of fullerenes. Central fullerene, which is described as a discrete set of sixty carbon atoms, plays a special role in the presented mathematical model. Angular oscillations and rotations of the central fullerene are described by the dynamic Euler equations. All other fullerenes have a centrally symmetric field of the potential of interaction with the surrounding atoms and molecules. In this regard, we use the hybrid discrete–continuous mathematical model with four potentials that describe the interactions between the surrounding fullerenes, smoothed fullerene and an atom, a pair of atoms, and electric charges. The results of a numerical study of influence of the Coulomb interaction on the rotational and translational motion of the C60 fullerene are presented.

In dynamic experiments using a highly sensitive torsion technique, the magnetic properties of the doped Rb3C60 single crystal are studied over a wide temperature range. The critical temperature of the superconducting transition Tc, the critical magnetic field Hc1, the pinning forces of both the Abrikosov vortices and the magnetic moments of dipoles at T >> Tc, at which relaxation processes are important, are determined and investigated. It was shown that the structural transition Fm3m-Pa3 at T = 260 K is accompanied by a reformation of the magnetic structure. Both the usual peaks at T ∼ 160–250 K and the not quite ordinary peaks of gigantic absorption of the energy of the oscillations, which shift to room temperature over time, were observed. The phenomenon is discussed in the framework of the cooperative Jahn-Teller effect, taking into account possible orbital and spin ordering. The relaxation processes at room temperatures (T ∼ 300 K) were studied. After many days of exposure (annealing) of fullerene at T ≥ 40 °C, in experiments with cooling from room temperatures, phenomena typical for a superconducting transition with giant pinning and damped oscillations were observed at T ∼ 200 K. The results of studies of magnetic phase transitions at T = 180–200 K in pure fullerite C60 (99.98% Term. Sublimed), which are related to the detected unusual magnetic phenomena in fullerene Rb3C60, are presented. [ABSTRACT FROM AUTHOR]

Abstract—X-ray diffraction, Mössbauer and Raman spectroscopy have been used to study structural phase transformations during mechanosynthesis of Fe–С60/70 in toluene with 20 and 25 at % С60/70 fullerite. The quantitative carbon content determines the phase composition of mechanocomposites. (Fe3C)D forms at 20 at % С60/70, whereas Fe7C3 and a paramagnetic phase form at 25 at % С60/70 at the initial stage of mechanical alloying. Free carbon is in an amorphous state in the sample. The formation mechanism of carbides and a paramagnetic component is discussed. [ABSTRACT FROM AUTHOR]

Comparative studies of the influence of carbon allotropic form on the formation of the structural-phase composition of copper-based composites have been performed by means of Scanning Electron Microscopy, X-ray and Thermal analysis and Raman spectroscopy. It has been stated that the kinetics of solid state reactions in the systems Cu-C 60/70 and Cu-C g obtained in process of mechanosynthesis depend on deformational stability and oxidation-reduction properties of fullerite and graphite. It has been shown that partial destruction of fullerene molecules in the Cu-C 60/70 sample results in the formation of an amorphous fullerite-like phase, copper oxide Cu 2 O, and supersaturated solid solution Cu(C, O). Total destruction of fullerene molecules in the system Cu-C 60/70 results in the formation of supersaturated solid solution Cu(C), just like in the case of the composite Cu-C g . [ABSTRACT FROM AUTHOR]

The nature of the linear term in the heat capacity of fullerite C60has been investigated. The low-temperature dependence of the sound velocity has been determined from the data of the heat capacity at temperatures below 4 K. A model of the dynamic configuration excitations (DCE) is proposed to describe the contribution of the linear term in heat capacity and calculate the dependence of sound velocity. It is shown that this model, apparently, adequately describes the dynamics of cluster formations of the short-range order in fullerite C60by taking into account excitations of both the atomic and electronic subsystems. In the framework of this model, it is shown that low-energy tunnel states that are located at the boundaries of C60domains make a dominant contribution to the low-temperature effects in the heat capacity and sound velocity of C60. [ABSTRACT FROM AUTHOR]

The mechanisms of thermal decomposition of evaporated material during Physical Vapor Deposition (PVD) process depend on the kind of evaporated material. Such parameters of PVD process as deposition rate, source temperature and deposition time should be carefully selected taking into account the properties of material. Deposited films can span the range of chemical compositions based on the source materials. The nanostructural carbon films in form of palladium nanograins embedded in various carbonaceous matrixes were obtained by thermal evaporation during PVD process from two separated sources containing C60 fullerite and palladium acetate, both in a form of powder. The evaporation was realized by resistive heating of sources under a dynamic vacuum of 10-3 Pa. The influence of decomposition path of evaporated materials on the film structure has been discussed. Prepared C-Pd films were characterized using thermo-gravimetric method, differential thermal analysis, infrared spectroscopy and X-ray diffraction. The influence of decomposition of Pd acetate and fullerite on the final film structure was also shown. [ABSTRACT FROM AUTHOR]

The results of the comparative study of deformation-induced structural changes in fullerite C 60/70 and graphite during their mechanical activation (MA) have been presented in the paper. It was shown that intensive deformation resulted in the destruction of the crystalline structure of fullerite C 60/70, with the formation of a fullerite-like phase at the initial stage and an amorphous graphite-like phase at long periods of MA, with time values determined by the energy density of the process. It was stated that the process of the destruction of fullerite crystalline structure was accompanied by deformation-induced destruction of fullerene molecules. It was also found that during MA the crystalline structure of graphite C g had essentially lower deformation stability than the crystalline structure of fullerite C 60/70 . [ABSTRACT FROM AUTHOR]

Special features of the solid-phase transformations of the composites Cu–fullerite and Cu–graphite in process of their mechanoactivation (MA) and further heating have been studied. It was stated that the form of carbon (fullerite, C 60/70 ; graphite, C g ) and its structural state in the composition of mechanocomposites Cu–С 60/70 and Cu–C g cause a dramatic effect on the oxidation of Cu. At the initial stage of mechanosynthesis (MS) (up to 2 h) copper oxide Cu 2 O was formed in the Cu–С 60/70 mixture. The reduction of this oxide was only possible upon the destruction of fullerene molecules, the necessary condition for which was the increase of mechanosynthesis time (more than 4 h) and heating in the range of 230–330 °С. No copper oxide was formed in the case of Cu–C g . [ABSTRACT FROM AUTHOR]

Structures of fullerites formed from fullerene-containing soots have been examined by electron-microscopy methods. The principle of identification of fullerene-containing materials has been proposed. The authors assume that one of the found morphostructures can be the initial step of formation of nanoindividuals of varying composition. [ABSTRACT FROM AUTHOR]

The paper overviews a historical evolution of the technology, knowledge, and application of various forms and allotropic modifications of carbon as a component and base for graphitized-carbon, vapor-phase, nanostructured, and composite materials and describes the development and implementation of the synthesis of high-pressure phases and diamond-based superhard materials. The chronology of the most important developments, discoveries, and applications of carbon and associated materials is presented. [ABSTRACT FROM AUTHOR]

Carbon fullerenes are well-known spherical clusters of carbon atoms. Due to their extraordinary chemical, physical and structural properties, these nanomaterials have already proved their significant potential for use in, almost, every technological field. Based on the success behind these hollow carbon molecules, a comprehensive theoretical attempt is made here to provide the fundamentals and describe the basic structural characteristics of a new family of fullerene-like nanomaterials called hereafter α-fullerynes. The proposed nanomaterials are derived from inserting acetylenic (C C C C) and butatrienic (C C C C) bonds in place of single and double carbon bonds in standard fullerenes. To ensure the chemical stability of the arisen molecules, i.e. α-fullerynes, an appropriate combination of bond order is utilized. Each three-bond structure may be either of the acetylenic (C C C C) or of the butatrienic (C C C C) type. To explore, develop, and optimize the geometry of these new spherical carbon molecules, the reactive force-field (ReaxFF) interatomic potential is adopted. In order to investigate the chemical stability of the developed α-fullerynes, their potential energies are computed and compared with those of the original generator fullerenes, while their structural and geometrical characteristics are discussed in detail. Then, molecular dynamics (MD) simulations are performed to study the structural properties, density, and stiffness constants of periodic crystal structures made by these nanomaterials called henceforward α-fullerytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Classical MD computer simulations are used as a tool for the theoretical investigation of the processes initiated in carbon-based materials by the irradiation with C60 and Ar n clusters. This paper shows the comparison of data regarding the chemical reactions occurring in polystyrene and fullerite bombarded by C60 and Ar n projectiles with the initial energy of 2.5 and 10 keV. Its main focus is to elucidate the influence of material type on the bond breaking as new bond formation processes induced by impinging cluster projectiles. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The fullerite films with texture (110) were prepared by the condensation of C60 molecules on KCl, LiF, and Si substrates. The hardness (? = 0,42 GPa) and Young's modulus (? = 14,1 GPa) of the fullerite films were determined by nanoindentation method at continuous scanning in depth. The results were compared with theoretical estimates of elastic modules and previous works on measurements of elastic characteristics and hardness of crystalline C60. [ABSTRACT FROM AUTHOR]

Refined mixed fullerenes were used as a reagent in known organic reactions instead of the pure fullerene C60with aim to find an alternative, low-cost method for the synthesis of fullerene derivatives potentially exhibiting photoconductive properties. The isolation of C60or C70in clean form without admixtures requires the use of large quantities of toluene or other nonpolar solvents, polluting the environment and multiplying the production cost. 1,3-Dipolar cycloaddition of azomethine ylide to fullerite was chosen because this reaction is one of the most widely used for fullerene functionalization, producing material possibly presenting photoinducing behavior. The data showed that the use of the cheaper mixed fullerenes instead of pure C60leads to the isolation of the same expected products with similar yields. The photoelectric properties of mixed fullerenes and their organic derivatives were also examined. A slightly semiconductive behavior was confirmed as well as a noticeable photoresponse. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications®to view the free supplemental file. [ABSTRACT FROM AUTHOR]

The structural investigations of fullerite films were performed using high-resolution electron microscopy, electron diffraction and electron energy loss spectroscopy and X-ray photoelectron spectroscopy. In particular defects such as dislocations, stacking faults and twins were studied in details. It was shown that fullerite films could be characterized by a face-centered cubic (f.c.c.) structure with lattice parameter a = 1.416 nm. They are distinguished for their rich polytypic structure that is caused by breaking of alteration of closely packed planes of (111) type. The quantitative method based on information theory using the 'run-length encoding' algorithm was suggested to evaluate the degree of disorder in the f.c.c structure of thin fullerite films. [ABSTRACT FROM AUTHOR]

The thermal behavior of a mixture of fullerites C was studied by X-ray diffraction and IR and UV spectroscopy. The temperature range in which the molecular and crystal states degrade was determined (825-875°C in a CO medium). In the C mixture, fullerenes decomposed at lower temperatures than in pure C and C; the decomposition temperature depended on the impurity (oxygen and solvent) content. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation of the C60-fullerite film irradiation by 5 keV electron beam at normal incidence has been performed. Average transverse coordinates of the primary and secondary electrons as well as the density of collisions of several types were drawn in dependence on the penetration depth. It was shown that a swarm of low energy secondary electrons provides efficient excitation of valence electrons and gives the main contribution to polymerization of C60-fullerite. [ABSTRACT FROM AUTHOR]

Abstract: Three C60 fragmentation regimes in fullerite bombarded by Cs+ are identified as a function of its energy. C2 is the major species sputtered at all energies. For E(Cs+)<1keV C2 emissions dominate. C2 and C1 have highest intensities between 1 and 3keV with increasing contributions from C3 and C4. Intensities of all fragments maximize around 2keV. Above 3keV, fragments’ densities stabilize. The roles of and the contributions from direct recoils and collision cascades are determined. Maximum direct recoil energy delivered to the fullerite''s C60 cage is ∼210eV at which only C2 emissions occur is identified and an explanation provided. The three fragmentation regimes under continued Cs+ bombardment eventually lead to complete destruction of the C60''s cages transforming fullerite into amorphous carbon. [Copyright &y& Elsevier]

Abstract: Diamond-like carbon films have been deposited from a fullerite target by ultra-short pulsed laser deposition technique. The results indicate that the films morphology and structure, determined by scanning electron microscopy, atomic force microscopy and energy dispersive X-ray diffraction, depend strongly on the substrate temperature. X-ray photoelectron, X-ray Auger electron, Raman and surface enhanced Raman scattering spectra indicate that the fs-DLC films composition involves a mixed sp, sp2 and sp3 carbon network consisting of aromatic rings and sp3 diamond-like structures linked by chains of different lengths and composition. The films deposited at room temperature, presenting the higher content of sp3 carbon (48%), also contain C60 crystalline phase and show a very high hardness of 49GPa. [Copyright &y& Elsevier]

Abstract: The fullerene is the fourth allotropic modification of carbon and its properties, as volume, gravimetric and electrochemical capacities, are in excess of many similar properties of metal hydrides and hydrocarbons. The solution of the problem of the reversible hydrogenation of each carbon atom in the frame of fullerene molecule will allow to create the hydrogen storage with the capacity up to 7.7 wt.% H. A series of experiments have been conducted to evaluate the full hydrogenation of fullerite C60; hydrofullerenes have been produced experimentally with the variable content of hydrogen. The optimum regime of C60 hydrogenation has been determined resulting in the full hydrogenation of fullerene molecule C60. As was apparent after the tests, the sequence of formation of hydrogenated fullerene molecule C60H60 in fullerite has been going in the following order: the molecular hydrogen dissolution in octahedral interstices of fcc lattice of fullerite, the dissociation of hydrogen molecules in going from octa- to tetrahedral interstices, the interaction of hydrogen atoms with fullerene molecule. It has been demonstrated that chemisorption process of hydrogen by molecule C60 is limited by diffusive processes in fullerite after hydrogen concentration conformed to C60H36. The spectral analysis have shown that the second stage process of chemisorption follows the compressive shell model. The suggestion of the model of processes going on at the interaction between H2 and fullerite C60 has been made. The mechanism for the definition of hydrogenation degree of molecule C60 has been proposed in the present paper. [Copyright &y& Elsevier]

The C60 fullerite has been Ca-intercalated under high pressure up to 240 kbar induced by a pressure shock wave. Magnetometric measurements have revealed superconductivity of the as-prepared sample at 9.9 K. The sample relaxed under normal conditions in the helium atmosphere has exhibited traces of superconductivity with the onset at T = 30 K. [ABSTRACT FROM AUTHOR]

Nanoparticles of iron oxide embedded in C60 matrices are synthesized by co-evaporation of iron and C60-fullerene, and analyzed using X-ray photoelectron spectroscopy, X-ray absorption near-edge structure spectroscopy and MOKE magnetometry. C60 molecules in the neighborhood of the iron oxide nanoclusters transfer charge to the oxide, and the charge deficit fully delocalizes onto the fullerene molecules. The composition of the nanoclusters of iron oxide is similar to both hematite and magnetite, in comparable proportions. One analyzes the amplitude of the pre-edge XANES peak, yielding the average ionization state of absorbing Fe atoms, which is confirmed by the simulations of XANES spectra. [ABSTRACT FROM AUTHOR]

C60 polymerization under high pressure and high temperature was studied in situ by angle-dispersive synchrotron diffraction employing a two-dimensional (2D) image plate detector. Preliminary results of this study show that heating fullerene C60 up to 450 °C at 7 GPa leads essentially to the well-known rhombohedral 2D-polymerized phase. In addition, in situ diffraction measurements show that the texture exhibited by the transformed sample results from the anisotropic polymerization occurring on the sample, which in turn is induced by the uniaxial stress component of the applied pressure. The polymerized lattice planes in the transformed sample are then aligned to the compression (uniaxial) axis. Diffraction analysis of the recovered sample has permitted us to identify the presence of a minor phase, the tetragonal 2D polymer. [ABSTRACT FROM AUTHOR]