Ti Grid Research Articles

Evaluation of 3D printed buckyball-shaped cathodes of titanium and stainless-steel for IEC fusion system

An inertial electrostatic confinement (IEC) fusion device accelerates ions, such as deuterium (D) or tritium (T), to produce nuclear fusion and generate neutrons. The IEC's straightforward configuration consists of a concentric spherical transparent cathode at a negative bias surrounded by a grounded spherical anode. The effects of cathode properties on the neutron production rate (NPR) remain, to date, inadequately studied. This study aims to determine the impact of the cathode material on the NPR by investigating fusion reactions on the cathode surface. Two buckyball-shaped cathodes made of stainless steel (SS) and titanium (Ti), both of 5 cm diameter, fabricated by selective laser melting and 3D printing, are used for this investigation. A SS spherical chamber of 25 cm inner diameter is used as an anode in this experiment. A performance evaluation of surface fusion reaction in the IEC using SS and Ti grids is conducted by examining the NPR as a function of the applied voltage and grid currents at different gas pressures. So far, IEC with Ti and SS cathodes achieves NPRs of 2.32 and 1.41 × 107 n/s, respectively, at 5.6 kW (70 kV, 80 mA). The normalized NPRs (NPR/I-cathode) from IEC using SS and Ti cathodes are compared. The results demonstrate that fusion reaction occurs on the cathode surface, and fusion increases with the applied voltage. The measured NPR/I-cathode using the Ti cathode is higher than that of the SS cathode by factors of 1.36–1.64 across the 20–70 kV range. Moreover, fusion on the Ti cathode surface enhances the total NPR significantly compared to the SS cathode under the same conditions. The Ti's considerable ability to accumulate D ions and molecules compared with that of SS explains the difference of measured NPR results.

High‐Temperature PIN Diodes Based on Amorphous Hydrogenated Silicon‐Carbon Alloys and Boron‐Doped Diamond Thin Films

Amorphous SiC:H (a‐SiC:H) diode structures with different ratios of Si:C are deposited on transparent conductive boron‐doped diamond‐coated fused silica substrates by plasma‐enhanced chemical vapor deposition. The boron‐doped diamond thin films have been deposited at temperature 720 °C on the fused silica substrates with a Ti grid used to enhance electrical conductivity. The thin‐film structures based on P‐type, Intrinsic and N‐type a‐SiC:H thin films, shortly a‐SiC:H PIN diodes, are characterized by current–voltage measurements under solar simulator illumination. For comparison, the same PIN structures are deposited on fluorine‐doped tin oxide. Before deposition of the diode structures, the surface morphology is studied by scanning electron microscopy, and undoped layers deposited on the quartz substrates are characterized by temperature‐resolved electrical resistivity, optical absorptance, Raman spectroscopy, and photoluminescence.

Low temperature synthesis of transparent conductive boron doped diamond films for optoelectronic applications: Role of hydrogen on the electrical properties

Transparent conductive electrodes are principal components in various optoelectronic devices and technologies. As such, diamond coatings in the form of electrically conductive thin films are envisioned to provide advantageous chemical and mechanical characteristics/stability in a variety of modern technologies including optoelectronics, biosensing, electrochemical and micromechanical systems. However, deposition of electrically conductive polycrystalline diamond coatings for such applications is currently a challenging task, since temperatures above 600 °C are usually required to ensure good diamond layer quality, which in turn limits the selection of substrates, to materials capable of withstanding exposure to high temperatures. In the present work, we investigate routes toward enhancement of electrical characteristics of nanocrystalline boron-doped diamond (BDD) films fabricated at low temperatures via chemical vapour deposition. We found that post-growth processing of BDD layers enhances their electrical properties, which otherwise are dependent on the employed deposition temperature regime. Finally, we show that integration of an electrically conductive Ti grid opens a route for fabrication of highly transparent and conductive composite nanocrystalline BDD electrodes over large areas at temperatures as low as 250 °C.

Electroluminescence of thin film p-i-n diodes based on a-SiC:H with integrated Ge nanoparticles

Hydrogenated amorphous substoichiometric silicon carbon alloys (a-SiC:H) with and without embedded Ge nanoparticles (NPs) have been prepared by plasma enhanced chemical vapour deposition combined with in-situ Ge evaporation and annealing on semi-transparent boron doped nano-crystalline diamond coated Ti grids. The presence of Ge NPs embedded in the amorphous phase has been confirmed by transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses. Current-voltage (I–V) characteristics and near infrared electroluminescence (EL) spectra were measured to compare performance of diodes. The relatively strong EL appears in diodes with integrated Ge NPs near the direct band-gap transition of Ge at about 0.82 eV with an intensity strongly correlating with current density. However, it has also been found that Ge NPs integrated into a-SiC:H significantly deteriorates diode I–V characteristic.

Enhanced Electrochemical Performance of Electropolymerized Self-Organized TiO2 Nanotubes Fabricated by Anodization of Ti Grid

Self-organized TiO2 nanotubes grown on Ti grid acting as anode for Li-ion microbatteries were prepared via an electrochemical anodization. By tuning the anodization time, the morphology and length of the nanotubes were investigated by scanning electron microscope. When the anodization time reached 1.5 h, the TiO2nts/Ti grid anode showed a well-defined nanotubes, which are stable, well adherent ~90 nm with a length of 1.88 µm. Due to their high surface utilization, surface area and material loading per unit area, TiO2nts /Ti grid anode using polymer electrolyte exhibited a high areal capacity of 376 µAh cm-2 at C/10 rate and a stable discharge plateau at 1.8 V without using a polymer binder and conductive additive. The storage capacity of the TiO2nts/Ti grid after 10 cycles is fifteen times higher compared to previous reports using planar Ti foils.

Optoelectronic Properties of Hydrogenated Amorphous Substoichiometric Silicon Carbide with Low Carbon Content Deposited on Semi‐Transparent Boron‐Doped Diamond

Hydrogenated amorphous substoichiometric silicon carbide (a‐Si1−xCx:H, x < 0,1) thin films and diodes with low carbon content are prepared from a mixture of H2, SiH4, and CH4 by plasma‐enhanced chemical vapor deposition at a relatively high temperature of 400 °C on semi‐transparent boron‐doped nanocrystalline diamond (B‐NCD) electrodes with an underlying Ti grid. Vibration spectra indicate that CH4 prevents Si crystallization at elevated deposition temperatures and confirm an increasing carbon content up to x = 0.1 for samples grown with SiH4/CH4 flows up to 1:3. Dark current–voltage characteristics of B‐NCD/a‐Si1−xCx:H diodes show a rectifying ratio of about four orders at ±1 V. However, under white light illumination, an energy conversion efficiency of 4% is limited by a high serial resistivity of the B‐NCD electrode and S‐shaped photocurrent near the open‐circuit voltage.

Taguchi method for optimization of immobilized Dy2O3/graphite/TiO2/Ti nanocomposite preparation and application in visible light photoelectrocatalysis process

In the first section of work, Taguchi's L9 orthogonal design was applied to investigate the effect of Dy2O3 and graphite masses, calcination temperature and voltage to prepare a new and optimized Dy2O3/graphite/TiO2/Ti electrode through the electrophoretic deposition process. The obtained optimum conditions with considering the visible light photoelectrocatalytic ability in decolorization and electrode stability were as follows: 7 mg Dy2O3, 50 mg graphite, calcination temperature of 400 °C and different voltage of 60 V. The results of SEM, EDX elemental mapping and XRD for the optimized Dy2O3/graphite/TiO2/Ti electrode indicated the uniform immobilization of Dy2O3, graphite and TiO2 particles on the Ti grid sheet. Moreover, the DRS approved the photo-absorption ability of the prepared electrode in the visible light range.In the second part, Taguchi's L16 orthogonal design was used to investigate the effect of pH, the number of Dy2O3/graphite/TiO2/Ti electrode(s), visible light power and applied bias potential on the photoelectrocatalytic ability of the prepared electrodes in the degradation of Maxilon Blue from well water. The obtained results showed that the maximum decolorization efficiency was achieved at the optimum conditions: pH of 10, two Dy2O3/graphite/TiO2/Ti electrodes, visible light power of 72 W and applied bias potential of 0.9 V. The decolorization efficiency of the photoelectrocatalysis process using the optimized electrodes was considerably higher than solo sorption, electrosorption and photolysis processes.

Fabrication of FeOx-Decorated on Ethanol Pretreated Ti Grids for Asymmetric Supercapacitors.

FeOx grown on titanium grids were synthesized by a hydrothermal approach and their electrochemical properties were investigated. Among all FeOx materials, FeOOH-decorated Ti grid with ethanol dried (Ti@FeOOH-1) exhibits a higher specific capacitance (159.7 F g-1 at a current density of 0.5 A g-1) than that of Fe₂O₃-decorated Ti grid with ethanol dried (Ti@Fe₂O₃-1) (51.9 F g-1 at a current density of 0.5 A g-1). However, the capacitance retention of Ti@Fe₂O₃-1 after 1000 cycles is about 83.3% of the initial capacitance while Ti@FeOOH-1 only keeps cycling performance with 67.7% retention. Considering the importance of high specific capacitance for supercapacitor, we chose Ti@FeOOH-1 as the electrode material in our experiment. An asymmetric supercapacitor was successfully fabricated using Ti@MnO₂ as the positive electrode and Ti@FeOOH-1 as the negative electrode. The tests show that the asymmetric supercapacitor has high specific capacitance (77 F g-1 at a current density of 1 A g-1) and excellent cycling ability (97.5% retention after 1000 cycles). The synthesis of FeOx grown on titanium grids brings new probability to design a potential negative electrode material for supercapacitors.

Tailoring ultrathin MnO2 nanosheets on chemically-modified titanium grids

In this work, we have developed a one-pot preparative route to fabricate MnO2 nanosheet arrays on surface modified titanium grids. Well-controlled fabrication pathways of such architecture are addressed. Interestingly, cobweb-like architecture on Ti grid is formed after surface modification, and ultrathin MnO2 nanosheet arrays are homogenously covered on such cobweb-like architecture to enhance contact surface area and close connection between these components to promote ions penetration and electron transport. Such unique method of modifying the surface of the metal substrate to load transition metal oxide nanostructures can be extended to diverse substrates.

Optically transparent composite diamond/Ti electrodes

It is important for electro-optical applications of nanocrystalline diamond (NCD) films to achieve high optical transparency with low electrical resistivity. However, currently fabrication of highly transparent NCD films with reasonable electrical conductivity remains a challenge – any increase in conductivity simultaneously reduces transparency. Here, we report on fabrication of highly conductive and yet highly transparent electrodes based on boron-doped nanocrystalline diamond (B-NCD) films and Ti grids. We studied B-NCD films with variable boron content and thickness to determine preferable electrical and optical characteristics. Composite electrodes with a sheet resistance of 200 Ω/sq and optical transparency of 80% have been obtained by the integration of a thin nanostructured Ti-grid, sandwiched between the glass substrate and B-NCD layer.

One-pot synthesis of pearl-chain-like manganese dioxide-decorated titanium grids as advanced binder-free supercapacitors electrodes

Pearl-chain-like MnO2 arrays on Ti grid have been fabricated by a facile hydrothermal approach and further investigated as the binder-free electrode for high-performance supercapacitors. This unique well-designed binder-free electrode exhibits a high specific capacitance (313.6Fg−1 at a current density of 0.5Ag−1), good rate capability (66.8% retention), and excellent cycling stability (92.4% capacitance retention after 2000 cycles). Moreover, an asymmetric supercapacitor is developed using the as-prepared MnO2 arrays as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode. The optimized asymmetric supercapacitor displays excellent electrochemical performance with an energy density of 24.9Whkg−1 at power density of 224.7Wkg−1. These impressive performances suggest that the pearl-chain-like MnO2 array on Ti grid is a promising electrode material for supercapacitors.

Bifacial quasi-solid-state dye-sensitized solar cells with metal selenide counter electrodes

Bifacial dye-sensitized solar cell (DSSC) is a promising solution to reduce the cost of photovoltaic conversion. We present here the experimental realization of bifacial quasi-solid-state DSSC from a TiO2 photoanode, a semitransparent gel electrolyte, and a Ti grid supported metal selenide (MSe, M=Co, Ni, Ru) counter electrode (CE). In comparison with front efficiency of 4.87% and rear efficiency of 1.19% for Ti grid supported Pt based DSSC, the efficiencies are enhanced to 6.51% and 1.84% on the solar cell with cost-effective Ti grid supported RuSe CE. The preliminary results demonstrate that this architecture is promising in realizing cost-effective bifacial quasi-solid-state DSSCs without sacrificing photovoltaic performances.

Ultraviolet-O2 treatment TiO2/Ti anodes for use in Ti grids-based large-area flexible dye-sensitized solar cells

Large-area flexible dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2/Ti anodes on the Ti foils and platinum/single-wall carbon nanotube (Pt/SWCNT) counter electrodes on the indium-doped tin oxide coated polyethylene naphthalate (ITO/PEN) substrates, were successfully assembled with Ti grids. The resistance of the DSSC could be observably reduced with the Ti grid, which could enhance the fill factor and the efficiency of the DSSC. Ultraviolet-O2 treatment of the TiO2/Ti anode could improve the efficiency of the DSSC, owing to that the passivated Ti foil was enhanced by the ultraviolet-O2 treatment. Based on the optimal preparation conditions, a large-area (40 cm2) flexible DSSC with efficiency of 5.29% was achieved under natural light intensity of 55 mW cm−2 measured outdoors.

Performance comparison of portable direct methanol fuel cell mini-stacks based on a low-cost fluorine-free polymer electrolyte and Nafion membrane

A low-cost fluorine-free proton conducting polymer electrolyte was investigated for application in direct methanol fuel cell (DMFC) mini-stacks. The membrane consisted of a sulfonated polystyrene grafted onto a polyethylene backbone. DMFC operating conditions specifically addressing portable applications, i.e. passive mode, air breathing, high methanol concentration, room temperature, were selected. The device consisted of a passive DMFC monopolar three-cell stack. Two designs for flow-fields/current collectors based on open-flow or grid-like geometry were investigated. An optimization of the mini-stack structure was necessary to improve utilization of the fluorine-free membrane. Titanium-grid current collectors with proper mechanical stiffness allowed a significant increase of the performance by reducing contact resistance even in the case of significant swelling. A single cell maximum power density of about 18 mW cm −2 was achieved with the fluorine-free membrane at room temperature under passive mode. As a comparison, the performance obtained with Nafion 117 membrane and Ti grids was 31 mW cm −2. Despite the lower performance, the fluorine-free membrane showed good characteristics for application in portable DMFCs especially with regard to the perspectives of significant cost reduction.

Efficient dye-sensitized solar cell sub-modules

Two topics with dye-sensitized solar cell (DSC) development were introduced. The one was development of an efficient glass–substrate 10 cm-by-10 cm DSC sub-modules with current-collecting Ag grids using N719 dye ( η ac = 8.0%, J sc = 16.8 mA/cm 2, V oc = 0.71 V, ff = 0.67). Accelerated long-term stability tests were conducted using JIS C-8938 environmental and endurance test methods for amorphous-Si solar cell modules, which included a dry heat cycle test (−40 °C to 90 °C, 200 cycles), a heat–humidity test (−40 °C to 90 °C with 85% humidity, 10 cycles) and a light-soaking test (255 W/m 2 (300–700 nm), 500 h). The results suggested DSC using methoxypropionitrile (MPN) electrolyte solvent has a promising future to commercialization of DSC. The other was development of a new preparation method for highly efficient plastic–substrate DSC. This method consisted of important basic technologies such as press without heat treatment, light-confining effect by light scattering TiO 2 large particles, binder-free water paste of TiO 2 and UV–O 3 treatment of TiO 2 photoelectrode. The plastic–substrate DSC prepared by this new method showed a very high efficiency, 8.1% (0.29 cm 2) under simulated solar light (100 mW/cm 2, AM1.5). Further, an efficient plastic–substrate 10 cm-by-10 cm DSC sub-module with current-collecting Ti grids using N719 dye ( η ac = 4.5%, J sc = 10.9 mA/cm 2, V oc = 0.72 V, ff = 0.57) was successfully prepared.

Facile Synthesis and Tensile Behavior of TiO2 One-Dimensional Nanostructures

High-yield synthesis of TiO2 one-dimensional (1D) nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO2 with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.

Chemometric investigation of the efficiency of different TiO(2)-based catalysts as principal components of TOC photochemical sensors under development.

There is an increasing demand for measurement of organic carbon in solutions both in industry and in environmental research for the purpose of continuous water-quality monitoring. Practically all the methods used are based on a catalytic system in which metal oxides play a major role. The development of a new TOC/DOC measurement system, in our work, uses a mixed anatase-rutile form of TiO(2 )as catalyst of the mineralisation process, and direct measurement of the CO(2) produced, by a gaseous diffusion electrode. The entire research is based on heterogeneous catalysis using an immobilised catalyst, which can offer considerable advantages over other methods of catalysis. Four different catalytic systems were analysed. Three involved thermal immobilisation of TiO(2) on glass supports (glass spheres and glassy particulates) or on an Al metal grid. One further system consisted of direct oxidation of a Ti grid at high temperatures. The system was illuminated using a 350 nm UV source (350 mW cm(-2)) contained in a home-made measurement cell. Five molecules-malic acid, pentachlorophenol, sodium dodecylsulfate, hydroquinone, and citric acid-which were deemed to be representative and had been investigated in several previous studies, were used as photodegradation targets. However, it was not possible to obtain a direct expression of "catalytic efficiency" simply by reading the data obtained, nor any indirect molecular "recalcitrancy" scale. Chemometric analysis, by principal components analysis, allows the five used catalytic systems to be easily compared each other and a single PC component is able to perform classification.

TEM sample preparation of superconducting oxides

The preparation and observation of high Tc superconducting TEM samples deserves a great deal of care since, as when characterizing any new material, mistreatment can bring about extrinsic features leading to erroneous conclusions. In dealing with materials such as these, where the structural origins of the electromagnetic properties are tantamount, this is especially true. The three most common practices of sample preparation are suspending crushed powder, ultramicrotomy, and ion-beam milling. The illustrations will be made with YBa2Cu3O7-x samples.The powder suspension technique requires grinding the material with a suitable mortar and pestle (e g., agate) to a size which will allow electron transparency. Dispersing the particles in a suitable solvent such as water or acetone prevents aggregation. If the sample has large amounts of extraneous phases, the choice of medium is crucial as reactions will occur. Ni or Ti grids (50 to 75 mesh) with carbon films are used to fish out the suspended particles.

In situ Chemical Vapor Deposition of Silicon

An AEI EM6 electron microscope was modified for the in situ chemical vapor deposition (CVD) of Si films by pyrolysis of SiH4 gas. The environmental cell was so constructed that 100 μm dia. apertures placed 1.6 mm apart formed the top and bottom of the CVD microchamber and permitted a gas flow of up to 0.4 cm3 (STP)/min at up to 10 torr. A current of 2 amps through a single 200 mesh Ti grid of 0.003 mm2 net cross sectional area is sufficient to heat the sample to ~1200°C. Some temperature-heater power calibration experiments were performed by observing the melting point of evaporated metal films.