Retarding Electrode Research Articles

Designing High-Donicity Anions for Rechargeable Potassium Superoxide/Peroxide Batteries.

A battery cathode based on the superoxide/peroxide redox not only inherits the advantage of oxygen (O2 ) batteries in high capacities and low costs but also overcomes the disadvantages in O2 storage, electrolyte evaporation, and anode deactivation due to O2 crossover. Herein, we report an enhanced potassium superoxide (KO2 )/peroxide (K2 O2 ) conversion by adopting a high-donicity anion additive in the ether-based electrolyte. Such an anion was synthesized via a "Solvent-in-Anion" strategy and validated to enhance the electron donicity of the electrolyte. The use of high-donicity anion could lead to enhanced KO2 utilization (≈90.2 %) by retarding electrode passivation and allow the full charging back of K2 O2 through the solution-mediated pathway without electrocatalysts. No apparent cell degradation is observed during the first 120 cycles by controlling the reversible depth-of-discharge capacity at 292 mAh g-1 within an O2 -free region. The K-KO2 cell delivers a high energy efficiency (>84.4 %) and a lifespan of over 1440 hours.

Designing High‐Donicity Anions for Rechargeable Potassium Superoxide/Peroxide Batteries

AbstractA battery cathode based on the superoxide/peroxide redox not only inherits the advantage of oxygen (O2) batteries in high capacities and low costs but also overcomes the disadvantages in O2 storage, electrolyte evaporation, and anode deactivation due to O2 crossover. Herein, we report an enhanced potassium superoxide (KO2)/peroxide (K2O2) conversion by adopting a high‐donicity anion additive in the ether‐based electrolyte. Such an anion was synthesized via a “Solvent‐in‐Anion” strategy and validated to enhance the electron donicity of the electrolyte. The use of high‐donicity anion could lead to enhanced KO2 utilization (≈90.2 %) by retarding electrode passivation and allow the full charging back of K2O2 through the solution‐mediated pathway without electrocatalysts. No apparent cell degradation is observed during the first 120 cycles by controlling the reversible depth‐of‐discharge capacity at 292 mAh g−1 within an O2‐free region. The K−KO2 cell delivers a high energy efficiency (>84.4 %) and a lifespan of over 1440 hours.

High-Performance Compact Pre-Lens Retarding Field Energy Analyzer for Energy Distribution Measurements of an Electron Gun.

The energy distribution of an electron gun is one of the most important characteristics determining the performance of electron beam-based instruments, such as electron microscopes and electron energy loss spectroscopes. For accurate measurements of the energy distribution, this study presents a novel retarding field energy analyzer (RFEA) with the feature of an additional integrated pre-lens, which enables an adjustment of beam trajectory into the analyzer. The advantages of this analyzer are its compact size and simple electrode configuration. According to trajectory simulation theories, the optimum condition arises when the incident electron beam inside the RFEA is focused on the center of a retarding electrode. Comparing I–V curves depending on whether the pre-lens working or not, it is confirmed that the use of the pre-lens dramatically improves the energy resolution and efficiency of the signal acquisition process. The pre-lens RFEA was applied to characterize a Schottky electron gun under various temperatures and extraction voltages as operational conditions. When the tip temperature was increased by 50 K, we were able to measure an energy distribution broadening of 13.8 meV with the proposed pre-lens RFEA. The relative standard deviation of energy distribution was 0.7% for each working condition.

Study and design of a lens-type retarding field energy analyzer without a grid electrode

A retarding field energy analyzer (RFEA) for measuring the energy distribution of charged particles offers the advantages of a simple structure and suitability for simultaneous observations of beam patterns in two dimensions. In this study, lens-based RFEAs without a grid electrode were theoretically investigated with regard to the geometry and lens condition to achieve high performance. The simulation results show that the proposed RFEA can achieve a resolution of 2.6 meV at an energy level of 500 eV. In addition, performance, which is the ratio of the resolution to the beam energy, reached 5.2×10−6. These results indicate that the RFEA designed in this study is capable of high-performance outcomes. The findings here demonstrate that the most important factors when attempting to realize a high-resolution RFEA design are to reduce the sagging effect of the electron beam through the focusing lens and ensure that V″(z) in the retarding electrode is close to zero. The design of the lens-based RFEAs is described in detail.

Design and experimental testing of a gas cluster ion accelerator**Supported by International Cooperation Program of the Ministry of Science and Technology of China (2015DFR00720), Wuhan Municipal Science and Technology Bureau (2016030409020219), Suzhou Scientific Development Project (ZXG201448) and Hubei Province Technological Innovation Project (2016AHB004)

A gas cluster ion beam (GCIB) system with cluster energy up to 12 keV has been designed. To facilitate pumping of the nozzle chamber and increased pressure of the gas source up to 10 atm, pulse mode was used for the gas feeding. Argon was employed as the working gas. To separate monomers from clusters, both electromagnet and retarding electrode were utilized. A maximal pulsed cluster current of 90 nA has been achieved. The shape of pulsed ion beam currents has been analyzed in detail at different applied magnetic and retarding electric fields.

A Low-Temperature External Electron Retarding Electrode for Improving Vertical Green LED Performance

To alleviate the mismatch between electron/hole velocities and improve the quantum efficiencies, the cobalt-doped ZnO (CZO) dilute magnetic films grown by pulsed-laser deposition at a low temperature of 100 °C were served as the external electron retarding n-electrodes for vertical InGaN light-emitting diodes (LEDs). The retardation of the electron mobility is owing to the scatter of electrons via the spin-orbit interaction of Co2+ ions and their corresponding ferromagnetic properties. A 150-nm-thick CZO film was chosen as the n-electrode for the vertical green LED (530 nm). In comparison to conventional lateral LED, the vertical LEDs without and with the CZO n-electrode had 21.3% and 39.6% improvements in the output power (at 350 mA), respectively. The vertical LED with the CZO n-electrode showed an increment in the light output power (at 350 mA) by 15.1% as compared with the vertical LED without the CZO n-electrode. Obviously, after inserting the CZO n-electrode, the excessively large mobility difference between the electron and hole carriers in the conventional vertical LED is reduced significantly, which can decrease the nonradiative recombination rate and improve the emission characteristic. The results also reveal the CZO film served as an external electron retarding electrode is highly potential for vertical LED applications.

Protection of Low-Carbon Steel from Carbon Dioxide Corrosion with Volatile Inhibitors. I. Liquid Phase

It was shown that many of the known basic inhibitors of atmospheric and hydrogen sulfide corrosion (D-4-3, N,N-diethylamino-2-methylbutan-3-one, and N,N-diethylaminoethanol) fail in CO2-containing electrolytes. Carbon dioxide corrosion in solution can be suppressed only in the presence of more hydrophobic octylamine and its higher homolog, namely, amine A. The new highly passivating inhibitors IFKhAN-72 and IFKhAN-74 are even more effective. IFKhAN-72 is superior to amine A (the best amine-based inhibitor among those studied) in protection effect and suppresses CO2 corrosion of steel over a wide temperature range by substantially retarding both electrode reactions. Because of its high penetrating ability, IFKhAN-72 can protect steel already covered with corrosion products. In addition, this inhibitor has a prolonged aftereffect.

Field ion appearance energy spectroscopy of CO + originated from Rh(111) and Au(111) surface step sites

Field ionization of CO at step sites of Rh(111) and Au(111) was studied with field ion microscopy and mass-to-charge resolved field ion energy spectroscopy. Using a newly developed retarding potential technique, absolute values for CO + field ion appearance energies were derived from measurements of the high energy onset of ion retardation curves and from in situ measurements of the work function of the retarding electrode. From analyses of the CO + field ion appearance energies, field ionization of CO on Rh and Au surfaces was found to proceed by field desorption. Applying a thermionic cycle, field-dependent values of the binding energy for CO on Rh(111) and Au(111) were derived. For comparison, CO field ionization was also studied at a passivated Rh surface. The mechanism of field ion imaging of metal surfaces with CO + ions and the field-dependent chemisorption of CO on different metal surfaces is discussed on the basis of experimental results and theoretical calculations.

An overview of the slow-positron beam facility at the photon factory, KEK

The KEK slow-positron source is in the final stage of construction. The beam line comprises a 31 m long vacuum duct within an axial magnetic field and a following electrostatic guided section. In order to vary the energy of a positron beam dedicated to depth-profile measurements, a high voltage station capable of applying 60 kV has been installed in the beam transport system. The target assembly (a water-cooled tantalum rod of 5 radiation lengths and a moderator with multiple tungsten vanes) and the following straight section (8 m; used for positron storage) are under high voltage. The beam duct located downstream is at ground potential. Positron beams passing through this region have a high kinetic energy. A focusing triplet quadrupole lens and a moderator on the retarding electrode are located at the end of the magnetic transport. This beam line has 9 right-angle-curved ducts, comprising a radius of curvature of 40 cm. Positrons with a maximum energy of 60 keV are guided by bending magnets attached to the beam-transport ducts. A transport system to switch from magnetically guided to electrostatically guided has been installed. The design of the brightness-enhancement stage of the positron beam for positron re-emission microscopy is in progress. In a preliminary experiments at 2.0 GeV with a 2 kW primary beam, 4×10 6e +/s of slow positrons were observed by detecting annihilation γ-rays at the end of the magnetic beam-transport line. Further improvements are expected by careful surface and thermal treatments of the moderator.

Minimum feature sizes and ion beam profile for a focused ion beam system with post-objective lens retarding and acceleration mode

The beam characteristics of a focused Ga+-ion beam (FIB) at ion energies between 10 and 150 keV have been investigated by using a 100 keV focused ion beam system with an additional post-objective lens retarding and acceleration electrode. Line structures with minimum feature sizes down to 20 nm almost independent of the landing energy of the ions could be realized by sputtering line patterns in a gold-coated GaAs substrate. The current density profile was determined over six orders of magnitude by measuring the radii of FIB-exposed dot structures as a function of the ion dose. The beam diameters have been found to be in the range between 30 and 45 nm, nearly independent of the available ion energies. The photoluminescence signal of locally intermixed AlGaAs/GaAs quantum well structures was used to study the spatial resolution of FIB-implanted line patterns. The results were compared with the lateral resolution, which can be calculated from the current density distribution of the beam profile.

High resolution focussed ion beam implantation with post objective lens retarding and acceleration

Abstract The focussing properties of a focussed ion beam system with a post objective lens retarding and acceleration electrode was investigated. Ga+ ions exposed PMMA samples show linewidths of 30 nm at 70 keV implantation energy. Using post objective lens retarding a minimum beam diameter of 20 nm (width of sputtered lines on a Au coated sample) was obtained for 10 keV Ga+ ions. In PMMA linewidths of 70 nm have been realized by using 10 keV Ga+ ions. Only a slight reduction of the resolution was observed with post objective lens acceleration up to 150 keVtotal ion energy.

Measurement of Surface Vacuum Potential from the Energy Spectrum of the Secondary Electron in the Scanning Electron Microscope

A measurement method for determining the contact potential between the specimen and the analyzer from an S-curve (an integrated curve of secondary electron energy distribution) in the scanning electron microscope is described. The measured S-curve is best-fitted to the calculated S-curve assuming the secondary electron energy distribution and the instrumental function of the analyzer. The work function of the retarding electrode in the analyzer was calibrated by the use of thermionic emission from a heated W filament. The work function of acid-cleaned Cu was 4.71 V, while that of untreated Al was 3.64 V. It is shown that the previously reported charging characteristics of an electrically floating gate in the MOS structure under electron beam irradiation are well explained by taking account of the surface vacuum potentials. The work function of insulator SiO2 was estimated to be on the order of 7 V.

Electron Trajectories Calculations of an Energy - Filtering Field-Emission Gun

In many cases, the contribution of beam energy spread to the limitation of the performances of an electron microscope is strong. In the case of the field emission gun (FEG) , Troyon has experimentally shown it is possible to reduce considerably the energy spread by energy filtering at the gun level. The system developed consists basically of a magnetic FEG with a retarding electrode working as the retarding electrode of an energy filter. The principle is recalled in Fig. 1 and the cross section of the accelerator is given in Fig. 2. In this paper, the results of electron trajectories calculations inside the energy filtering field emission gun (EFFEG) are given.Fig. 3 shows that electrons of same energy, but entering the retarding field with different angles, can have exit angles very different. Due to the work function of approximately 4.5 eV the electrons, for an extracting potential Vo = 2 kV, enter in the field of the retarding electrode with an energy smaller than 2 keV. In Fig. 3 trajectories are computed for an electron of 1996 eV. Electrons passing by the nodal points have the same entering and exit angles. Trajectory 1 in Fig. 3 corresponds to an entering radius re = 17.5 μm and an entering semi angle αe = 1.2 mrad. For these re and αe values, at Vr =6 V, the exit semi angle αs = αe . Fig. 3 shows that an electron entering parallely to the axis, even very close to the axis (re = 10 μm) has a larger exit angle than electrons passing by the nodal points.

Optical system for a low-energy focused ion beam

A low-energy focused ion beam (FIB) would be a very useful tool for shallow doping with low damage density to the substrate. For a low-energy FIB, an optical system using a retarding field is advantageous because of a low chromatic aberration coefficient which could not be reduced with a conventional column. Some evaluations were made for an optical column with a retarding electrode for practical use. The secondary electron trajectories within the equipotential space were calculated by the surface-charge method, and some secondary-electron images were observed with an experimental column having a retarding electrode.

Pulsed field emission electron or ion gun with energy filter

A field emission gun consisting of a preaccelerating lens, a retarding electrode and a post accelerating anode is described and proposed to generate a pulsed beam with monochromator effect. The working principle is such that the preaccelerating lens focuses a magnified image of the source at the optical center of the accelerating stage so as to work in the constant angular magnification mode.

The Retarding-Field Tube as a Detector for Any Carrier Frequency

The rectifying effect of the retarding-field detector even at extremely high frequencies is due to the nonlinear retarding-field characteristic curve. The more detailed discussion of the retarding-field circuit as a "resistance transformer" shows the advantage of loading on the grid side. The extremely sensitive regulation of the retarding-field potential is avoided by high-resistance shunting of the retarding-field electrode. As excitation and rectification cannot be superposed in a retarding-field tube without interference, a receiver has been developed with two separate tubes, and this in turn led to the twin receiver. In the effort to apply the high-frequency voltages in a closed parallel wire system to the retarding electrode alone, a push-pull arrangement with a special tube was developed. In this tube the retarding electrode is divided into two segments. From this there was developed an exceedingly simple decimeter-wave receiver that is tuned only by means of the grid voltage. The high sensitivity of the retarding-field detector suggests its use for the rectification of any carrier frequencies, in which, nevertheless, the internal retarding resistance creates difficulties. By capacitative short-circuiting of the high-frequency current transfer perfect no-power control of the retarding-field detector, and consequently a sensitivity greater than that of all the other rectifiers, is obtained. At the same time the retarding-field detector can deliver a regulating voltage in a suitable phase for fading compensation.