Physico-chemical and electrochemical characterization of Ti/RhOx–IrO2 electrodes using sol–gel technology

Sol–gel technology has been successfully used for the incorporation of RhO_x–IrO₂ on a Ti substrate. RhO_x–IrO₂ was prepared from chloride precursors of Rh and Ir, for surface studies. These metal oxides were then immobilised on solid Ti substrates via dip withdrawal coating methods to form thin films. The Ti/RhO_x–IrO₂ thin films were extensively characterized in terms of surface characterization and chemical composition and used in the oxidation of phenol. Thermo-gravimetric analysis (TGA) determined the calcination temperature at 700 °C where no further structural changes occurred due to mass loss. The rhodium oxide showed two-phase formations, RhO₂ and Rh₂O₃, which were attributed to high calcinated temperatures compare to one phase IrO₂ which was stable at lower temperatures. The scanning electron microscopy (SEM) showed that the morphology of the film was found to be rough with a grain-like appearance in the 150-nm range. The phase composition of these metal oxides was determined by X-ray diffraction (XRD) technique and found to have crystalline structures. The results obtained from Rutherford backscattering spectrometry (RBS) revealed information regarding the chemical composition of the metal oxides and confirmed the diffusion of Rh and Ir into the Ti substrate. Electrochemical characterization of the Ti/RhO_x–IrO₂ electrode, via cyclic voltammetry (CV), showed distinctive redox peaks: anodic and cathodic peaks associated with the oxidation and reduction of the ferricyanide–ferrocyanide couple was seen at 250 and 100 mV respectively; the peak observed at 1000 mV was associated with oxygen evolution and a broad reductive wave at −600 mV can be ascribed to the Ti/RuO_x–IrO₂ reduction, which proved that the Ti/RhO_x–IrO₂ electrode were electroactive and exhibit fast electrochemistry.     

An initial investigation of the microstructure of Ti/Pd/Au ohmic contact structures for gaas microwave devices applications

A preliminary investigation of both as-deposited and annealed titanium (75 nm), palladium (75 nm), gold (400 nm), ohmic contacts to thinp ⁺-GaAs layers, was carried out using a combination of transmission electron microscopy, energy dispersive x-ray analysis, secondary ion mass spectroscopy and electrical measurements. The annealed contacts showed limited interaction between the metallization and the semiconductor with a metal penetration depth of only 2 nm for a 4 minute anneal at 380° C. The contacts were found to remain layered after annealing. The layers consisted of a uniform upper layer of large a Au(Ga) grains, a central, non-uniform layer containing small Pd-rich grains and a lower uniform layer of almost pure Ti. Preliminary SIMS studies suggested Zn dopant outdiffusion from the epilayer into the metal layer and this may have important implications for the electrical properties of these contacts.     

Metal-organic chemical vapor deposition of β-In2S3 thin films using a single-source approach

Dithioimidobisdiisopropylphosphinato indium chloride In[(SPⁱPr₂)₂N]₂Cl has been shown to be an effective single-source precursor for the deposition of indium sulfide films by aerosol-assisted chemical vapor deposition (AACVD). X-ray powder diffraction (XRPD) studies indicated that polycrystalline -In₂S₃ films with the tetragonal phase have been deposited on glass substrates (425–475 °C). The morphology of films was confirmed by scanning electron microscopy (SEM). Energy dispersive X-ray analysis (EDAX) indicates the presence of indium and sulfur.     

New synthetic routes for quantum dots

Various methods for the synthesis of quantum dots of compound semiconductors are discussed. Emphasis is placed on methods involving the decomposition of chalcogenide-containing precursors in tri-n-octylphosphine oxide. The use of simple coordination complexes can avoid the use of pyrophoric precursors. Approaches based on melts or the use of imino-bisdichalcogeno-diphosphinates are also discussed. These routes may be suitable for the production of large quantities of quantum dots.     

Controllability on classical Lie groups

We consider the problem of accessibility and controllability of certain bilinear systems. These evolve on Lie groups whose Lie algebras are the normal real forms of complex simple Lie algebras. Previous results by other authors were obtained under the assumption that the controlled vector field is strongly regular. Our paper is aimed at weakening this requirement, and involves relating the root structure of elements in a Lie algebra as above to the nodal connection graphs obtained from their standard matrix representations. This is in turn related to a standard irreducibility assumption on the uncontrolled vector field. The abstract results on generation of Lie algebras are of some independent interest. The work of this author was supported in part by a Fulbright grant, while she was visiting the Arizona State University, and by the Centro de Matemática da Universidade de Coimbra/INIC. The work of this author was partially supported by AFOSR Contract No. 85-0224A.     

Fatal accidental dibucaine poisoning in children

Dibucaine is a potent amide anesthetic available in over-the-counter preparations. Compared with lidocaine, substantially lower doses of dibucaine may result in seizures, dysrhythmias, and death. We present three fatal cases of accidental dibucaine ingestion in children and discuss the toxicity, treatment, and prevention of such ingestions.     

The effects of precision and small impedance branches on power flowrobustness

Renewed interest at EPRI on improved power flow techniques is due to the recent improvements in the robustness of fast power flow algorithms. In this paper the authors investigate two interacting parameters which affect convergence in power flow algorithms, limited precision and small impedance branches. Analytical methods and experimental results are given for predicting the minimum convergence tolerance achievable by an algorithm as a function of the infimum of the set of branch impedance values, and the number of bits of mantissa precision. Methods are suggested for increasing the virtual precision at minimal computational cost and for scanning power flow input data to determine whether available precision is sufficient