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We created a unique sodium ion battery (NIB, SIB) cathode based on selenium in cellulose-derived carbon nanosheets (CCNs), termed Se-CCN. The elastically compliant two-dimensional CCN host incorporates a high mass loading of amorphous Se (53 wt%), which is primarily impregnated into 1 cm3 g−1 nanopores. The results in facile sodiation kinetics due to short solid-state diffusion distances and a large charge transfer area of the nanosheets were established. The architecture also leads to an intrinsic resistance to polyselenide shuttle and to disintegration/coarsening. As a Na half-cell, the Se-CCN cathode delivers a reversible capacity of 613 mA h g−1 with 88% retention over 500 cycles. The exceptional stability is achieved by using a standard electrolyte (1 M NaClO4 EC-DMC) without secondary additives or high salt concentrations. The rate capability is also superb, achieving 300 mA h g−1 at 10C. Compared to recent state-of-the-art literature, the Se-CCN is the most cyclically stable and offers the highest rate performance. As a Se–Na battery, the system achieves 992 W h kg−1 at 68 W kg−1 and 384 W h kg−1 at 10144 W kg−1 (by active mass in a cathode). We are the first to fabricate and test a Se-based full NIB, which is based on Se-CCN coupled to a Na intercalating pseudographitic carbon (PGC) anode. It is demonstrated that the PGC anode increases its structural order in addition to dilating as a result of Na intercalation at voltages below 0.2 V vs. Na/Na+. The {110} Na reflections are distinctly absent from the XRD patterns of PGC sodiated down to 0.001 V, indicating that the Na metal pore filling is not significant for pseudographitic carbons. The battery delivers highly promising Ragone chart characteristics, for example yielding 203 and 50 W h kg−1 at 70 and 14000 W kg−1 (via total material mass in the anode and cathode).

A key advancement target for oxygen reduction reaction catalysts is to simultaneously improve both the electrochemical activity and durability. To this end, the efficacy of a new highly conductive support that comprises of a 0.5 nm titanium oxynitride film coated by atomic layer deposition onto an array of carbon nanotubes has been investigated. Support effects for pure platinum and for a platinum (50 at %)/nickel alloy have been considered. Oxynitride induces a downshift in the d-band center for pure platinum and fundamentally changes the platinum particle size and spatial distribution. This results in major enhancements in activity and corrosion stability relative to an identically synthesized catalyst without the interlayer. Conversely, oxynitride has a minimal effect on the electronic structure and microstructure, and therefore, on the catalytic performance of platinum-nickel. Calculations based on density functional theory add insight with regard to compositional segregation that occurs at the alloy catalyst-support interface.

Nearly monodispersed 1.6 nm Ir, 2.3 nm Pd nanoparticles, 2.7 nm Pd(core)–Ir(shell) and 2.2 nm Pd–Ir alloys with mixed surface atoms were synthesised in the presence of polyvinylpyrrolidone (PVP) and studied in the atmospheric ring opening of indan. The nanoparticles and supported catalysts were characterised by UV–vis spectroscopy, TGA, TEM, EDX, TPR, XPS, ISS and XANES. The nanoparticle size and structure control allowed insights into the bimetallic catalyst functioning. As soon as two contiguous surface Ir atoms exist on the nanoparticle surface, they display the same catalytic properties, most likely through the dicarbene ring-opening mechanism. Palladium serves only as a dispersing agent in Pd(core)–Ir(shell) structures providing 100% Ir dispersion, or as an inert surface diluting metal in Pd–Ir formulations with mixed nanoparticle surface. The Pd–Ir core–shell structure allows maximum selective ring-opening yield, which is 19% higher than that for the industrial Pt–Ir catalyst.

Selective ring opening of naphthenic molecules in oil upgrading should result in no loss in molecular weight. Benzocyclopentane (indan) ring opening was studied under hydrogen atmospheric pressure at 609 K over poly-(vinylpyrrolidone)-stabilized Ru, Ir and Pd monometallic and Ru–Ir and Ru–Pd bimetallic nanocatalysts prepared by simultaneous reductions. The particle size (mostly within 2 nm) and their monodispersity were confirmed by transmission electron microscopy, while X-ray photoelectron spectroscopy indicated the bimetallics' alloy structure. Pd catalysts displayed the lowest activity in the ring opening; Ru showed the highest formation of undesired o-xylene and lights. Monometallic Ir displayed the highest activity and selectivity toward 2-ethyltoluene and n-propylbenzene. In bimetallic structures, higher Ir content led to improved catalytic performance. Next to the monometallic Ir catalyst, the newly developed Ru1Ir4/γ-Al2O3 catalyst (with 1 : 4 molar ratio of Ru to Ir) displayed superior single cleavage selectivity as well as lower cracking activity compared to industrial Pt–Ir catalysts at a comparable indan conversion. The study can pave the way in the development of Pt-free Ru-containing catalysts with narrow size distributions for selective ring opening, especially taking into consideration a possibility of their higher S-resistance as compared to the Pt catalysts.

We employed a polypyrrole hydrogel precursor to create a carbon framework that possesses both huge heteroatom content (13 wt% nitrogen and 11 wt% oxygen) and high surface area (945 m 2 g −1 ) that is equally divided between micropores and mesopores. A sodium ion capacitor (NIC, HIC) electrode fabricated from this N and O Functionalized Carbon (NOFC) has tremendous reversible capacity and rate capability, e.g. 437 mA h g −1 at 100 mA g −1 , and 185 mA h g −1 at 1600 mA g −1 . This is among the most favorable reported, and is due to copious nanoporosity that enables fast ion sorption at the many N and O moieties and graphene defects. The NOFC imbues a NIC device with energy–power characteristics that are not only state-of-the-art for Na hybrids, but also rival Li systems: Ragone chart placement is 111 W h kg −1 and 38 W h kg −1 at 67 W kg −1 and 14,550 W kg −1 , respectively, with 90% capacity retention at over 5000 charge/discharge cycles.

The adsorption of xanthate on pyrite has been extensively studied. However, the adsorption mechanisms remain a subject of controversy. Formation of both dixanthogen and metal-xanthate complexes has been suggested. In this study, both room temperature X-ray photoelectron spectroscopy (XPS) (RT-XPS) and liquid nitrogen temperature XPS (Cryo-XPS) were used to study interactions between pyrite and xanthate. While dixanthogen was not detected by RT-XPS, it was successfully identified through C1s and S 2p peaks using Cryo-XPS. The impact of pH and copper activation on adsorption of xanthate on pyrite was also investigated. It was found that at low pH, dixanthogen is the dominant species of xanthate adsorption on pyrite. At high pH, metal-xanthate complexes were found to be prevalent on pyrite surfaces, which are responsible for the surface hydrophobicity. Copper activation showed a significant effect on xanthate adsorption on Cu-activated pyrite, resulting in mostly the formation of Cu-xanthate complexes rather than dixanthogen, mainly in the form of Cu(I)-isopropyl xanthate complex (CuIPX). Copyright © 2012 John Wiley & Sons, Ltd.

Depth profiling of NbxO/W multilayered samples was carried out using O2+, Cs+ or Ar+ beams of different energies (2 keV, 1 keV and 0.5 keV). The obtained depth profiles showed that sputtering with O2+ or Ar+ beams can reveal the distribution of light elements, while sputtering with Cs+ cannot show correctly their distribution if lower energy of 0.5 keV is applied. SRIM simulations show that changes in primary energy of sputter ions have much stronger effect on deposited energy incl. vacancy/ion and sputter yields than for oxygen and argon ion beam etching. It is suggested that O2+ or Ar+ sputter sources should be used when both light and heavy species are present in nano-scale multilayered targets. Copyright © 2012 John Wiley & Sons, Ltd.

We created a unique SnO 2 –Graphene Dual Aerogel (SnO 2 /GDA) nanocomposite with exquisite lithium and sodium ion battery anode performance (LIB, NIB NAB SIB). In parallel we employed electrochemical methods to be the first to analyze the transition from kinetic control to diffusion control for the conversion reaction (SnO 2 +4Li + +4e − ↔Sn+2Li 2 O) vs. for the alloying reaction (Sn+ x Li + + x e − ↔Li x Sn, x ≤4.4). The material displays a high reversible capacity (1299 mA h g −1 for Li at 0.1 A g −1 , 448 mA h g −1 for Na at 0.05 A g −1 ), very good cycling life (148% after 450 cycles for Li, 82% from 20 to 200 cycles for Na), and superb rate capacity retention (450 mA h g −1 for Li at 25 A g −1 , 184 mA h g −1 for Na at 1 Ag −1 ). In fact, these rate capabilities are among the most favorable reported in literature for each system.

This is the first report of a hybrid sodium ion capacitor (NIC) with the active materials in both the anode and the cathode being derived entirely from a single precursor: peanut shells, which are a green and highly economical waste globally generated at over 6 million tons per year. The electrodes push the envelope of performance, delivering among the most promising sodiation capacity–rate capability–cycling retention combinations reported in the literature for each materials class. Hence the resultant NIC also offers a state-of-the-art cyclically stable combination of energy and power, not only in respect to previously but also as compared to Li ion capacitors (LICs). The ion adsorption cathode based on Peanut Shell Nanosheet Carbon (PSNC) displays a hierarchically porous architecture, a sheet-like morphology down to 15 nm in thickness, a surface area on par with graphene materials (up to 2396 m2 g−1) and high levels of oxygen doping (up to 13.51 wt%). Scanned from 1.5–4.2 V vs. Na/Na+ PSNC delivers a specific capacity of 161 mA h g−1 at 0.1 A g−1 and 73 mA h g−1 at 25.6 A g−1. A low surface area Peanut Shell Ordered Carbon (PSOC) is employed as an ion intercalation anode. PSOC delivers a total capacity of 315 mA h g−1 with a flat plateau of 181 mA h g−1 occurring below 0.1 V (tested at 0.1 A g−1), and is stable at 10 000 cycles (tested at 3.2 A g−1). The assembled NIC operates within a wide temperature range (0–65 °C), yielding at room temperature (by active mass) 201, 76 and 50 W h kg−1 at 285, 8500 and 16 500 W kg−1, respectively. At 1.5–3.5 V, the hybrid device achieved 72% capacity retention after 10 000 cycles tested at 6.4 A g−1, and 88% after 100 000 cycles at 51.2 A g−1.

Clusters of independently tailored areal density and size distribution were grown on semiconductor surfaces by molecular beam epitaxy and were used subsequently as masks for selective ion beam modification. Field emission scanning electron microscopy shows sharp interfaces between the amorphous area exposed to ion beams and areas of crystalline silicon covered by clusters. Partial etching of the substrate leads to narrow trenches around the initial cluster site, suggesting significantly enhanced etching near the amorphous-crystalline interface. The results are explained on the basis of a slight density variation in the substrate near the cluster periphery due to a break in symmetry of the recoil atom incorporation. Computer simulations were carried out to further characterize these results, using a program based on the well-established TRIM code to model atomic collision cascades in a matrix. The resulting density distributions correlate well with the experimentally observed wet etching patterns, strongly suggesting a relation between cluster-masking related density variations in the amorphized silicon and the etching rate.

The structure of (100) silicon implanted with Zn+ ions at an energy of 50 keV was studied. The ion doses were varied from 1×1015 to 1×1017 cm−2 and the beam current density was 10 μA cm−2. The analytical techniques employed for sample characterization included cross‐sectional transmission electron microscopy and x‐ray energy dispersion analysis. The energy deposition of the ion beam was calculated by using computer simulation codes. For the two lower doses of 1×1015 and 1×1016 a crystalline‐to‐amorphous transformation was observed in the implanted layer and this was correlated with the thermal history of the implants and the attendant changes in morphology. In contrast, an amorphous‐to‐crystalline transition was found to occur at higher doses, namely 5×1016 and 1×1017, where the formation of a complex, structured layer consisting of an amorphous phase mixed with crystalline grains of Zn and partly recrystallized Si was identified together with other specific structural features. Detailed characterization ...

This work is part of a series of investigations started a few years ago to study high fluence ion beam effects. Experimental and computer techniques are applied here to the implantation of 40 keV As + in (111) Si samples at doses ranging from 1 × 10 16 to 2 × 10 17 cm −2 . The experimental evolution of the profile was analyzed by 2 MeV RBS spectroscopy. A special procedure was used to deconvolute the RBS data for highly nonhomogeneous layers. The atomic collision cascades were also simulated by a dynamic computer code, based on sputtering yield values and impurity depth distributions resulting from the well-known static code TRIM.SP. The distributions were used as input data to a procedure which takes into account the modification of the stopping power, the surface erosion by sputtering and the lattice relaxation.

Mesa structures and thin membranes are obtained by means of wet anisotropic etching using the etch-stop effect of nitrogen-implanted silicon. Dynamic Monte Carlo simulation is applied to calculate the implanted nitrogen profile. The use in sensor technology of nitrogen ion implantation in silicon with doses as low as 5×10 16 cm −2 is described.

Depth profiling of 200 A Al thin films on Si substrates is performed experimentally using oxygen in the ion beam source or in the analysis chamber. These depth profiles are also obtained by dynamic Monte Carlo simulation. In addition to the simulation of the ballistic cascade development, the computer code also includes additional chemically guided atomic relocation mechanisms. The comparison between experiment and simulation on the one hand, and between the two profiling methods on the other yields information about the target modification induced by the use of reactive species.

Depth distributions of displaced atoms for boron and arsenic implanted (111) silicon have been studied both by RBS channeling measurements and by a Monte Carlo simulation technique. The experiments and calculations are compared for ion energies of 80 and 160 keV and different doses. The computer code based on TRIM depth distributions takes into account the accumulation, diffusion and migration of the implantation-induced defects.

structures implanted with 50-keV boron ions is studied by deep-level transient spectroscopy (DLTS) measurements. The DLTS spectra of ion-implanted samples exhibit one peak which corresponds to a deep level located in the forbidden gap of the silicon matrix at Ec-0.40 eV below the conducting band edge. New additional shallower levels are found in the spectra following bombardment by high-energy electrons, the peak intensity being dependent on the irradiation dose. The corresponding activation energy of the created defects, the density of the traps, and the electron-capture cross sections are evaluated.

A method based on a thermocouple detector measuring simultaneously the total flux of energetic particles and the portion of the charged particles is proposed and studied. These data allow the neutral fraction of the ion beam to be easily calculated and the fraction is determined for different values of the working gas pressure in Ar and SF 6 . The results obtained are in good agreement with the theoretical model, for an ion beam accelerating bias of 500 V.

(1 0 0)-oriented silicon substrates were implanted with 50 keV Te + or Pb + ions at room temperature with doses varied in the range 1×10 15 to 1×10 18 cm −2 . Formation of ion beam-assisted Te and Pb nanocrystals in the layer amorphised by the implantation has been established. The accumulation of impurities, sputtering and formation of high-dose implantation profile was modelled by a dynamic computer simulation code. The calculated concentration profiles at various ion fluences were compared with the measured RBS profiles and the depth distribution of ion beam-induced nanoclusters obtained by cross-sectional transmission electron microscopy (XTEM), in an attempt to clarify the role of these effects in the formation of precipitates at high-dose irradiation conditions.

It has been shown [Todorov and Fossum, J Vac Sci Technol , B6 , 466 (1988)] that ultra-thin ( d ≈ 50 A) oxide films can be grown on silicon surfaces at reduced substrate temperatures using oxygen-containing low energy ion beams ( E

A secondary ion mass spectrometer with high energy, angle and mass resolution is used to study the energy and angular distributions of ions sputtered from molybdenum (110) surface under 4 keV argon beam bombardment. The sputtering at different beam orientations is also simulated by the MARLOWE computer code. The sputtering yields, in addition to the angular distribution of sputtered particles are assessed as a function of a given angle and energy.

Transmission sputtering of thin (up to 300 A) gold films bombarded by 10 to 20 keV Ar ions is simulated by using the MARLOWE computer code. The energy spectra, angle of ejection and depth of origin distributions of ejected particles are presented. The results indicate that even for a thin film the cascading of the recoils is sufficient to produce an E−2 energy spectrum and a cosine angular distribution. The evaluated transmission-sputtering yields for various film thicknesses are compared with the amount of gold retained in a silicon substrate in dynamic recoil mixing experiments.

Thin 15 nm bilayers of antimony on silicon, or a thin 10 A antimony marker layer buried in a matrix of silicon, were irradiated with 10 keV Ar+ at room temperature with fluences in the range from 5 × 1014 to 3 × 1016 ions cm-2 Sputtering of the antimony film during ion irradiation was compensated for by simultaneous controlled deposition (dynamic mixing). 2 MeV helium backscattering was used to study the resulting films and to examine the interfacial changes occuring as a result of ion beam mixing. The amount of mixing was found to be proportional to ϕ12. The mixing efficiency was found to be in reasonable agreement with previously reported data using 200–300 keV bombarding ions but it was an order of magnitude higher than that obtained using the linear cascade mixing conditions of Sigmund and Gras-Marti. The effect of film thickness on mixing was investigated by varying the antimony film thickness in the range 50–200 A and the results were compared with those obtained using a computer simulation model based on the MARLOWE code and using a Thomas-Fermi potential with a screening length suggested by Firsov. There appears to be good agreement between the simulated and the experimentally obtained data.

Thin polyimide films deposited on silicon or metal covered glass-ceramic substrates were exposed to ion bombardment at different fluences ranging from 1 × 1012 to 1.5 × 1016 cm−2. The XPS technique was used to study the polymer stoichiometry of the near surface layers (∼ 75 A) before and after the bombardment. The results show that the stoichiometric ratio of O, N and C-groups remains approximately constant with depth for unirradiated samples. A relative enrichment of C (probably in phenyl or CHx groups) occurred in the implanted samples. Scission of CN and C=O bonds was observed, the latter being complete at doses above 1014 cm−2. Desorption of O and N was also found.

Sputtering of copper, nickel and alumium polycrystalline targets by 40 keV Ar + ions is simulated by a NIARLOWE-based computer code. Angle-of-incidence dependence of sputtering yields and depth-of-origin distributions are calculated. The angular distributions and energy spectra of sputtered particles are similar to those found earlier for low-energy sputtering.

The reflection of argon ions with an energy of 50 to 500 eV from a copper single crystal is simulated on a digital computer. Three models are used to describe the interaction of the projectiles with the crystal: 1. the ion interacts in each moment only with the nearest crystal atom, 2. the ion interacts with all atoms of some microcrystallite whose atoms are assumed to be free, 3. the ion interacts with a microcrystallite of bound lattice atoms. For the Ar+–Cu and Cu–Cu interaction we use the Born-Mayer potential. A comparison of the results on the spatial and energy distributions of the ions in the different models is made. [Russian Text Ignored].

The scattering of Ar, Ne, and He ions from the Cu {100} face has been investigated by a digital computer technique; only binary elastic collisions of ions with the lattice atoms have been considered; the angular and energy distribution at various directions of incidence are discussed. The scattering by surface atomic chains and its contribution to the general picture of ion reflection were also studied.

Lattice disordering has been studied both experimentally by RBS-channelling measurements and theoretically by a Monte Carlo calculation technique. Single-crystal (100) silicon has been phosphorus implanted with an energy of 60 keV at room temperature in a 7° off-axis direction. The implanted doses varied between 5 x 10 14 and 4 x 10 15 cm −2 . Channelling measured distribution of displaced atoms is compared with damage profiles in phosphorus implanted silicon calculated by the computer code TRIM.