Controlled synthesis of fullerenes and endohedral metallofullerenes in high frequency arc discharge

The article presents the high-frequency arc discharge setup operating in helium atmosphere and applicable for the syntheses of carbon condensate with different dispersion and structure, along with fullerenes and endohedral metallofullerenes. It also highlights how the change of helium pressure in chamber can control the amount and composition of products in carbon condensate. The setup can be applied for the purposes of analysis, for instance in order to obtain information about the process of fullerenes and endohedral met-allofullerenes formation. Also, the fact that the yield of higher fullerenes is increasing with the pressure rise, whereas the yield of endohedral metallofullerenes is decreasing suggests different formation mechanisms.     

Radiochemical approaches for formation of endohedral fullerenes and MD simulation

The formation of atom-doped fullerenes has been investigated by using several types of radionuclides produced by nuclear reactions. From the trace of the radioactivities after a high performance liquid chromatography, it was found that formation of endohedral fullerenes (or heterofullerenes) of small atoms (Be, Li), noble-gas atoms (Kr, Xe) and 4B–6B elements (Ge, As, Se, Sb, Te, etc.) is possible by a recoil process following the nuclear reaction. In order to show the possibility of creating endohedral fullerenes with a suitably high kinetic energy of foreign atoms, we have carried out large-scale ab initio molecular dynamics simulations on the basis of the all-electron mixed-basis approach with atomic orbitals and plane waves for several atoms.     

Radiochemical approaches for formation of endohedral fullerenes and MD simulation

The formation of atom-doped fullerenes has been investigated by using several types of radionuclides produced by nuclear reactions. From the trace of the radioactivities after a high performance liquid chromatography, it was found that formation of endohedral fullerenes (or heterofullerenes) of small atoms (Be, Li), noble-gas atoms (Kr, Xe) and 4B–6B elements (Ge, As, Se, Sb, Te, etc.) is possible by a recoil process following the nuclear reaction. In order to show the possibility of creating endohedral fullerenes with a suitably high kinetic energy of foreign atoms, we have carried out large-scale ab initio molecular dynamics simulations on the basis of the all-electron mixed-basis approach with atomic orbitals and plane waves for several atoms.     

Controlled surface ordering of endohedral fullerenes with a SrTiO(3) template

The ability to select the way in which atoms and molecules self-organize on a surface is important for synthesizing nanometre scale devices. Here we show how endohedral fullerenes (Er(3)N@C(80)) can be assembled into four distinctive arrangements on a strontium titanate surface template. Each template pattern correlates to a particular reconstruction on n-doped SrTiO(3)(001), made in whole or in part by self-assembled arrays of non-stoichiometric oxide nanostructures. Close-packed assemblies of Er(3)N@C(80) molecules are formed, as well as one-dimensional chains and two-dimensional grids. This method of template-assisted molecular ordering provides a new platform for the development of experimental schemes of classical and quantum information processing at the molecular level.     

Luminescent metal nanoclusters: controlled synthesis and functional applications

Luminescent metal nanoclusters that consist of only several, to tens of, metal atoms and which possess sizes comparable to the Fermi wavelength of electrons have recently attracted significant attention. This new class of luminescent materials not only provides the missing link between atomic and nanoparticle behaviors in metals but also they present abundant novel information for the development of new applicable material systems to meet urgent needs in many areas (such as ultrasensitive sensors for heavy metals, bioimaging, as well as information technology) mainly because of their attractive characteristics, including ultra-small size, good dispersibility, excellent biocompatibility and photostability. In this review, we summarize recent advances in the controlled synthesis and application of luminescent metal nanoclusters, with a particular emphasis on Pt, Mo, Bi and alloy clusters. We also speculate on their future and discuss potential developments for their use in sensors, bioimaging and energy harvesting and conversion.     

Continuous-flow lithography for high-throughput microparticle synthesis

Precisely shaped polymeric particles and structures are widely used for applications in photonic materials, MEMS, biomaterials and self-assembly. Current approaches for particle synthesis are either batch processes or flow-through microfluidic schemes that are based on two-phase systems, limiting the throughput, shape and functionality of the particles. We report a one-phase method that combines the advantages of microscope projection photolithography and microfluidics to continuously form morphologically complex or multifunctional particles down to the colloidal length scale. Exploiting the inhibition of free-radical polymerization near PDMS surfaces, we are able to repeatedly pattern and flow rows of particles in less than 0.1 s, affording a throughput of near 100 particles per second using the simplest of device designs. Polymerization was also carried out across laminar, co-flowing streams to generate Janus particles containing different chemistries, whose relative proportions could be easily tuned. This new high-throughput technique offers unprecedented control over particle size, shape and anisotropy.     

The apparatus for diamond synthesis

A high-pressure apparatus, whose cavity is formed by openings of two oppositely located calipers surrounded by an angular body, has been considered. Parameters, at which the pressure created in the cavity is kept by the forces of friction without the use of a press, have been defined. A scheme of a plant that allows a group of apparatuses to be driven by one press has been suggested.     

A novel high-throughput fatigue testing method for metallic thin films

Abstract

Thin films are used in a wide variety of computing and communication applications although their fatigue behavior and its dependence on alloying elements are not very well known. In this paper, we present an experimental implementation of a novel high-throughput fatigue testing method for metallic thin films. The methodology uses the fact that the surface strain amplitude of a vibrating cantilever decreases linearly from the fixed end to the free end. Therefore, a thin film attached to a vibrating cantilever will experience a gradient of strain and corresponding stress amplitudes along the cantilever. Each cantilever can be used to extract a lifetime diagram by measuring the fatigue-induced damage front that progresses along the cantilever during up to 10⁸ load cycles.     

A novel high-throughput fatigue testing method for metallic thin films

Thin films are used in a wide variety of computing and communication applications although their fatigue behavior and its dependence on alloying elements are not very well known. In this paper, we present an experimental implementation of a novel high-throughput fatigue testing method for metallic thin films. The methodology uses the fact that the surface strain amplitude of a vibrating cantilever decreases linearly from the fixed end to the free end. Therefore, a thin film attached to a vibrating cantilever will experience a gradient of strain and corresponding stress amplitudes along the cantilever. Each cantilever can be used to extract a lifetime diagram by measuring the fatigue-induced damage front that progresses along the cantilever during up to 10⁸ load cycles.     

The biaxial-compression apparatus for diamond synthesis

A device for diamond synthesis, the pressure cavity of which is formed by radially positioned four step punches enclosed in the body, has been suggested. Each punch is connected with the body by two mutually perpendicular planes, one of which is parallel to the cavity axis and the other is inclined to it.     

Multistep synthesis of metal sulfide clusters: A novel zeolite modification method

A general approach has been proposed for incorporating high concentrations of modifier metals into high-silica zeolites. MFI zeolites have been modified with mono- and polymetallic sulfide clusters of copper, manganese, zinc, cobalt, and nickel. The metal incorporation sequence and the nature of the anion have been shown to influence both the total content and the ratio of the modifiers in the zeolite. Using multistep syntheses, we have prepared zeolites containing superstoichiometric amounts of modifier metals. Using a variety of physicochemical characterization techniques, the zinc-containing sample has been shown to have a uniform modifier distribution. The Cu-MFI-50 and Mn-MFI-50 zeolites have been characterized by electron paramagnetic resonance and shown to contain isolated Cu²⁺ and Mn²⁺ ions stabilized on the aluminum lattice site.     

Lattice and spin bipolarons in metal oxides and doped fullerenes

We extrapolate the BCS theory to the strong electron-phonon and (or) electron-spin fluctuation interaction and show that in the strong-coupling limit the ground state is a charged Bose liquid of lattice and (or) spin bipolarons. Kinetic and thermodynamic properties of charged bosons on a lattice in the normal and superconducting states are discussed, and some evidence for the model is given from NMR, neutron scattering, near-infrared absorption, Hall effect, resistivity, thermal conductivity, isotope effect, heat capacity, and critical magnetic fields of high-T _c oxides. The maximum attainableT _c is estimated to be in the region of the transition from the Fermi liquid to a charged Bose liquid (polaronic superconductivity). The proposed theory is not restricted by low dimensionality and might be applied to cubic oxides such as the old BaPbBiO and to alkali-doped C₆₀ as well.We thank D. Khmelnitskii, W. Liang, J. Loram, M. Pepper, E. Salje, and J. Wheattey for helpful stimulating discussions, and J. Cooper, A. Carrington, and A. Mackenzie for extensive experimental data and discussion. A. Bratkovsky has been instrumental in elaborating the temperature dependence of the infrared absorption and the electrical conductivity. One of us (A.S.A.) appreciates the financial support from the Leverhulme Trust.     

A novel method for the synthesis of perovskite-type mixed metal oxides by the inverse microemulsion technique

Nanoparticles of lanthanum-nickel, lanthanum-copper and barium-lead oxalates with the metal molar ratios of 11, 21 and 11, respectively, have been successfully synthesized in inverse microemulsions. These metal oxalate particles of about 20 nm diameter were readily calcined into single-phase perovskite-type LaNiO₃, La₂CuO₄ and BaPbO₃. The calcination temperatures for these metal oxalates were generally 100–250°C lower than those for the metal oxalates prepared by the conventional aqueous solution precipitation method. The substantial reduction in the calcination temperatures is attributed to the formation of uniform, near-spherical nanoparticles of the metal oxalate precursors obtained by the unique inverse microemulsion technique.     

Interaction control between endohedral metallofullerene and metal substrate by introducing alkanethiol self-assembled monolayer

The interaction control between endohedral metallofullerenes and a metal substrate has been demonstrated by introducing hexanethiol, octanethiol, and decanethiol self-assembled monolayers (SAMs) as the interlayer. We observe the electric properties of terbium endohedral metallofullerenes (Tb@C82) on alkanethiol SAMs with different chain lengths by scanning tunneling microscopy (STM) and spectroscopy (STS). Based on the comparison of the high-resolution STM images of a Tb@C82 molecule on hexanethiol and octanethiol SAMs, the interaction between Tb@C82 and a hexanethiol SAM is found to be larger than that between Tb@C82 and an octanethiol SAM; this is because at 68 K, the rotational states of Tb@C82 terminate only on the hexanethiol SAM. Furthermore, we find that the tunneling current-voltage characteristics of Tb@C82 on the hexanethiol SAM show the rectifying effects that are also caused by the molecular energy level shifts of Tb@C82 molecules due to the large interaction.     

Facile and controlled synthesis of FeCo nanoparticles via a hydrothermal method

Magnetic FeCo alloy nanoparticles have been synthesized by reduction of FeSO₄ and CoCl₂ with hydrazine in concentrated alkaline media via a hydrothermal route. The size could be controlled by synthetic conditions such as reaction time and temperature, respectively. The obtained samples were characterized by XRD, SEM, TEM, and VSM techniques. Magnetic investigations show the ferromagnetic behavior with saturation magnetization higher than 148.2 emu/g and maximum coercivity up to 411.0 Oe at room temperature. The present method is simple, inexpensive, surfactant-free, and may stimulate technological interests. Such FeCo alloy nanoparticles may have potential applications in biomedical field and magnetic storage devices.     

Comparative analysis of two methods for synthesis of fullerenes at different helium pressures

Abstract

The results of the effect of helium pressure in the chamber on the amount and composition of the produced fullerenes (C₆₀, C₇₀, etc.) synthesized in the arc plasma with graphite electrodes are presented. The findings obtained when the arc is powered by a direct (DC) and alternating (AC) currents of low frequency were compared in the same chamber with the electrodes located at the same angle to each other. These two methods are drastically different. The complete conversion of graphite into fullerene soot in AC occurs, but a part of the graphite is converted into a cathode deposit that does not contain fullerenes in DC, the relative amount of which increases when decreasing the helium pressure in the chamber. The highest fullerene content in fullerene soot of 10.2?wt.% is produced at a pressure of 127.5?kPa in AC arc, but in DC arc, the highest content of fullerenes in fullerene soot of 8.3?wt.% is produced at a pressure of 33.3?kPa.