Mass analyser optics for wide-beam ion sources in ion implantation systems

Ion implantation systems, used for producing high-current ion beams, employ wide-beam ion sources which are rotated through 90 degrees . These sources need mass analyser optics which are different from the conventional design. The authors present results of calculation of the image distance as a function of entrance and exit angles of a sector magnet mass analyser having such a source. These computations have been performed for the magnetic deflection angles 45 degrees , 60 degrees and 90 degrees . The details of the computations carried out using the computer program MODBEAM, developed for this purpose, are also discussed.

Effect of grain size and texture on the mechanical properties of warm worked cadmium-1.5 Pct zinc alloy

The structural changes occurring during warm working of Cd-1.5 pct Zn alloy and their effect on the subsequent mechanical properties are studied. It is observed that changes in grain size and preferred orientation are important to a large extent in controlling the mechanical strength. The Hall-Petch slope,R decreases in the warm worked material while the friction stress, σo increases. The lowerR values are attributed to the development of a (101l) texture and the higher σo values are interpreted on the basis of changes in the basal texture.

Optimization of ion energy spread in inductively coupled plasma source designed for focused ion beam applications

The ion energy distribution of inductively coupled plasma ion source for focused ion beam application is measured using a four grid retarding field energy analyzer. Without using any Faraday shield, ion energy spread is found to be 50 eV or more. Moreover, the ion energy distribution is found to have double peaks showing that the power coupling to the plasma is not purely inductive, but a strong parasitic capacitive coupling is also present. By optimizing the various source parameters and Faraday shield, ion energy distribution having a single peak, well separated from zero energy and with ion energy spread of 4 eV is achieved. A novel plasma chamber, with proper Faraday shield is designed to ignite the plasma at low RF powers which otherwise would require 300-400 W of RF power. Optimization of various parameters of the ion source to achieve ions with very low energy spread and the experimental results are presented in this article. (C) 2010 Elsevier Ltd. All rights reserved.

Microwave driven hydrothermal synthesis of LiMn2O4 nanoparticles as cathode material for Li-ion batteries

Among the various cathode materials studied for Li-ion batteries over the past many years, spinet LiMn2O4 is found to be one of the most attractive materials. Nanoparticles of the electrode materials sustain high rate capability due to large surface to volume ratio and small diffusion path length. Nanoparticles of spinel LiMn2O4 have been synthesized by microwave hydrothermal technique using prior synthesized amorphous MnO2 and LiOH. The phase and purity of spinel LiMn2O4 are confirmed by powder X-ray diffraction. The morphological studies have been investigated using field emission scanning electron microscopy and high-resolution transmission electron microscopy. The electrochemical performances of the material for Li insertion/extraction are evaluated by cyclic voltammetry, galvanostatic charge-discharge cycling and AC impedance studies. The initial discharge capacity is found to be about 89 mAh g(-1) at current density of 21 mA g(-1). (C) 2010 Elsevier B.V. All rights reserved.

Direct current electrical resistivity of zinc borate glasses containing transition metal oxides

The resistivities of zinc borate glasses containing Fe2O3, V2O5, and Fe2O3 + V2O5 have been measured as a function of composition and temperature. The values of resistivity and activation energy decrease as the transition metal oxide content is increased. The conductivities of the glasses containing Fe2O3 + V2O5 are more than the sum of those of the glasses containing only Fe2O3 or V2O5 (i.e. the activation energies are less than the sum of those in the glasses containing only Fe2O3 or V2O5). The results are discussed in terms of existing theories.

Discharge studies in a triode ion plating system

A triode ion plating system with a hot cathode has been described. The performance of the system is studied, by studying the discharge behaviour from the bias voltage and bias current point of view, at the substrate, for different anode currents, filament voltages and pressures. The observed substrate bias current for different operating parameters is not found to be normal. The behaviour is explained on the bias of ionisation at the respective electrodes. The studies have revealed the importance of inter-electrode spacing in the enhancement of ionisation, in ion plating systems, at lower pressures.

Relaxation dominated by inertia: Solvation dynamics of a small ion in a dipolar solvent

It is shown from an analytical theory that the solvation dynamics of a small ion can be controlled largely by the inertial response of the dipolar solvent when the liquid is in the underdamped limit. It is also shown that this inertial response arises primarily from the long wavelength (with wavevector k≃0) processes which have a collective excitation-like behaviour. The long time decay is dominated by the processes occurring at molecular lengthscales. The theoretical results are in good agreement with recent computer simulation results.

Selective sorption of ferric ion onto a crosslinked resin bearing triphenylphosphinimine residues

A polymeric sorbent containing triphenylphosphinimine residues has been obtained from crosslinked chloromethylated polystyrene by azidation, using phase-transfer catalysis, followed by reaction with triphenylphosphine at room temperature. The sorbent exhibits 100 % sorption selectivity for Fe(III) in the presence of Cu(II), Fe(II), Ni(II), Co(II), Mn(II), and Zn(II) in aqueous media. In the absence of Fe(III), however, Fe(II) is selectively sorbed over the other metal ions, and in the absence of both Fe(II) and Fe(III), Cu(II) has the highest selectivity of sorption on the resin. The sorption of Fe(III) is sensitive to pH, being maximum at pH not, vert, similar 2 and falling sharply at both higher and lower pH values. The sorbed Fe(III) is easily stripped with dilute HCl and the resulting protonated resin is regenerated to its original sorption capacity by treatment with dilute NaOH at room temperature.

Terminal solid solubilities at 900–1000°C in the magnesium oxide-zinc oxide system measured using a magnesium fluoride solid-electrolyte galvanic cell

The terminal solid solubilities of the periclase (MgO-rich) and zincite (ZnO-rich) solid solutions in the MgO---ZnO system have been determined by measuring the activity of MgO using a solid-state galvanic cell of the type 02(g), Pt/MgO, MgF2//MgF2//{χMgO+(1-χ)ZnO}(s, sln), MgF2/Pt, O2(g) in the temperature range 900–1050°C. The ZnO activity was calculated by graphical Gibbs-Duhem integration. The activity-composition plots of both components exhibit a strong positive deviation from ideality and are characterised by a miscibility gap. The terminal solid solubilities of the periclase and zincite solid solutions obtained from the activity-composition plots are found to be in reasonable agreement with those reported in the literature.

Sensitive high-resolution ion microprobe U-Pb dating of prograde and retrograde ultrahigh-temperature metamorphism as exemplified by Sri Lankan granulites

Ultrahigh-temperature (UHT) granulites of the central Highland Complex, Sri Lanka, underwent some of the highest known peak temperatures of crustal metamorphism. Zircon and monazite U-Pb systems in granulites near Kandy, the highest grade region (similar to 1050 degrees C; 0.9 GPa), preserve both a record of the timing of prograde and retrograde phases of UHT metamorphism and evidence for the ages of older protolith components. Zircon grains from a quartz-saturated granulite containing relics of the peak UHT assemblage have remnant detrital cores with dates of ca. 2.5-0.83 Ga. Date clusters of ca. 1.7 and 1.04-0.83 Ga record episodes of zircon growth in the source region of the protolith sediment. Two generations of overgrowths with contrasting Th/U record metamorphic zircon growth at 569 +/- 5 and 551 +/- 7 Ma, probably in the absence and presence of monazite, respectively. The age of coexisting metamorphic monazite (547 +/- 7 Ma) is indistinguishable from that of the younger, low-Th/U zircon overgrowths. Zircon from a quartz-undersaturated monazite-absent UHT granulite with a mainly retrograde assemblage is mostly metamorphic (551 +/- 5 Ma). The ca. 570 Ma zircon overgrowths in the quartz-saturated granulite probably record partial melting just before or at the metamorphic peak. The ca. 550 Ma zircon in both rocks, and the ca. 550 Ma monazite in the quartz-saturated sample, record post-peak isothermal decompression. A possible model for this pressure-temperature-time evolution is ultrahot collisional orogeny during the assembly of Gondwana, locally superheated by basaltic underplating, followed by fast extensional exhumation.

Ion-acoustic solutions and shock waves in multicomponent plasmas

The present investigation of ion-acoustic waves is based on the study of the nonlinearity of plasma waves in a dispersive medium. Here the authors study ion-acoustic solitary waves in a warm ion plasma with non-isothermal electrons and then the results for solitary waves in a plasma with isothermal electrons are obtained. Incorporating the previous results obtained from the solitary wave solutions, the authors generalize the effect of negative ions on ion-acoustic waves in plasmas consisting of either a warm or cold ion species. A reflection phenomenon of ions in these waves is also studied. These results can be generalized, but the discussion is limited to a particular model of the plasma.

Impedance parameters and the state-of-charge. III. Zinc-manganese dioxide and magnesium-manganese dioxide dry batteries

The problem of non-destructive determination of the state-of-charge of zinc- and magnesium-manganese dioxide dry batteries is examined experimentally from the viewpoint of internal impedance and open-circuit voltage at equilibrium. It is shown that the impedance is mainly charge-transfer controlled at relatively high states-of-charge and progressively changes over to diffusion control as the state-of-charge decreases in the case of zinc-manganese dioxide dry batteries. On the other hand, the impedance is mainly diffusion controlled for undischarged batteries but becomes charge-transfer controlled as soon as there is some discharge in the case of magnesium-manganese dioxide batteries. It is concluded that the determination of state-of-charge is not possible for both types of batteries by the measurement of impedance parameters due to film-induced fluctuations of these parameters. The measurement of open-circuit voltage at equilibrium can be used as a state-of-charge indicator for Zn-MnO2 batteries but not for Mg-MnO2 batteries.