Diagnostics of degradation processes induced by pulsed electric signals at the aluminum-silicon interface

Thermal conditions in an aluminum metallization stripe deposited onto a single crystal silicon substrate have been studied during the passage of single rectangular electric pulse with a current density of j < 8 × 10¹⁰ A/m² and a duration of τ = 100–1000 μs. Based on the results of this analysis, a method of diagnostics of the state of metallization contact systems and determination of the conditions of their safe operation is proposed.     

Degradation processes induced by nonstationary electric signals in metallization systems on silicon

The temperature regimes of operation of an aluminum metallization layer on a silicon plate have been analyzed for the passage of an electric pulse with a current density buildup rate of Δj/Δt ≤ 1.5 × 10¹⁴ A/(m² s). The temperature dynamics in this system has been calculated and compared to the experimental results. Degradation processes in the metallization layer-silicon structure have been observed, which are related to the formation of a liquid phase at the metal-semiconductor interface and the contact melting of a metallization layer under the conditions of nonstationary heating.     

Specific features of ion-initiated processes during pulsed laser deposition of MoSe2 coatings in pulsed electric fields

Experimental data and results of mathematical modeling have been used to determine the energy characteristics of an ion beam used to assist pulsed laser deposition (PLD) of MoSe₂ layers under conditions of positive high-voltage pulses applied to a laser-ablated target. It is shown that PLD assisted by implantation of ions at energies up to 100 keV can be used to obtain MoSe2 coatings on ⁵⁷Fe-containing substrates. Analysis of the concentration-depth profiles of Mo, Se, and ⁵⁷Fe atoms and the phase composition of a near-surface layer in samples shows evidence for mass transfer domination in thermal spikes and a significant influence of ion impact on the structure of this layer at the nanoscale. These features are manifested by the formation of a nanocomposite structure with inclusions of a specific hexagonal FeSe phase. The obtained results demonstrate the existence of principally new possibilities of using the proposed modified PLD method for controlled formation of solid lubricant coatings with improved properties.     

Wurtzite-type ZnS nanoparticles by pulsed electric discharge

The synthesis of wurtzite-type ZnS nanoparticles by an electric discharge submerged in molten sulfur is reported. Using a pulsed plasma between two zinc electrodes of diameter 5 mm in molten sulfur, we have synthesized high-temperature phase (wurtzite-type) ZnS nanocrystals with an average size of about 20 nm. The refined lattice parameters of the synthesized wurtzite-type ZnS nanoparticles were found to be larger than those of the reported ZnS (JCPDS card no 36-1450). Synthesis of ZnMgS (solid solution of ZnS and MgS) was achieved by using ZnMg alloys as both cathode and anode electrodes. UV-visible absorption spectroscopy analysis showed that the absorption peak of the as-prepared ZnS sample (319 nm) displays a blue-shift compared to the bulk ZnS (335 nm). Photoluminescence spectra of the samples revealed peaks at 340, 397, 423, 455 and 471 nm, which were related to excitonic emission and stoichiometric defects.     

Studying electromigration of melted inclusions in aluminum-silicon system

The formation and electromigration of melted aluminum-silicon (Al-Si) inclusions in single-crystalline silicon and polycrystalline aluminum has been studied. It is established that, in a temperature interval of T = 850–920 K, the contact melting in the Al-Si system is accompanied by the formation of melted zones (inclusions) with dimensions within 50–800 μm. These inclusions exhibit electrostimulated migration (j ≤ 4 × 10⁶ A/m²) along the lines of an applied electric field. The dependence of the specific velocity of melted zones on their sizes has been measured for the electromigration of Al-Si inclusions in silicon and aluminum crystals. It is suggested that the mechanism of melted zone migration consists in the melting and crystallization due to thermoelectric phenomena at interphase boundaries and electromigration in the volume of inclusion. Effective charges on Al and Si atoms in Al-Si melts and the Peltier coefficients in the corresponding crystal-melt systems have been experimentally determined     

脉冲钨离子注入导致的空洞效应

采用由金属蒸汽真空弧(metalvaporvacuumarc,简称MEVVA)离子源引出的强束流脉冲钨离子对H13钢进行了离子注入表面改性研究。在注入剂量为1×1017cm-2,温度为200℃以下,观察到强束流脉冲钨离子注入导致的空洞和空洞的硬化及脆化效应,分析了空洞对注入钨元素浓度深度分布的影响,基于热峰效应(spike),讨论了空洞的形成原因及其与材料耐磨性的关系。     

Degradation of DMSO by ozone-based advanced oxidation processes

The present study investigates the oxidation of dimethyl sulfoxide (DMSO) by conventional ozonation and the advanced oxidation processes (AOPs). The major degradation products identified were methanesulfinate, methanesulfonate, formaldehyde, and formic acid in ozonation process. The subsequent degradation of intermediates shows that methanesulfonate is more resistance to ozonation, which reduces the mineralization rate of DMSO. The effect of t-butanol addition and ozone gas flow dosage on the degradation rate was evaluated. The rate constant of the reaction of ozone (k(D)) with DMSO was found to be 0.4162 M(-1)S(-1). In the second part of this study, DMSO degradation and TOC mineralization were investigated using O(3)/UV, O(3)/H(2)O(2) and UV/H(2)O(2) processes. In all theses processes the degradation of target organics is more pronounced than TOC removal. The efficiencies of these processes were evaluated and discussed. The formation of sulfate ion in all AOPs have been identified and compared with other processes. Overall it can be concluded that ozonation and ozone-based AOPs are promising processes for an efficient removal of DMSO in wastewater.     

Degradation of cyanobacteria toxin by advanced oxidation processes

Advanced oxidation processes (AOPs) using O(3), H(2)O(2), O(3)/H(2)O(2), O(3)/Fe(II), and Fenton treatment were investigated for the degradation of aqueous solutions of cyanobacteria. The effects of concentration of reactants, temperature, and pH on toxins degradation were monitored and the reaction kinetics was assessed. O(3) alone or combined with either H(2)O(2) or Fe(II) were efficient treatment for toxins elimination. A higher toxin oxidation tendency was observed with Fenton reaction; total toxins degradation (MC-LR and MC-RR) was achieved in only 60s. The ozonation treatment was successfully described by second-order kinetics model, with a first-order with respect to the concentration of either ozone or toxin. At 20 degrees C, with initial concentration of MC-LR of 1mg/L, the overall second-order reaction rate constant ranged from 6.79 x 10(4) to 3.49 x 10(3)M(-1)s(-1) as the solution pH increased from 2 to 11. The reaction kinetics of the other AOPs (O(3)/H(2)O(2), O(3)/Fe(II), and Fenton), were fitted to pseudo first-order kinetics. A rapid reaction was observed to took place at higher initial concentrations of O(3), H(2)O(2) and Fe(II), and higher temperatures. At pH 3, initial concentration of toxin of 1mg/L, the pseudo first-order rate constant, achieved by Fenton process, was in order of 8.76+/-0.7s(-1).     

Determining the error in reproducing continuous random signals by means of pulsed frequency transducers

Conclusions Owing to the application of the suggested parameters , , _ge, and m which characterize the PFM system, it is possible to approximate the error relationships by means of linear functions convenient for calculations. The suggested technique can be applied for determining modulation and restoration errors of voltage-to-frequency and frequency-to-code transducers for various signal distribution laws and correlation functions.Translated from Izmeritel'naya Tekhnika, Vol. 19, No. 6, pp. 25–26, June, 1976.     

Measuring the period of digital electric signals

The errors of measurement of the period of digital signals approximated by rectangles and trapeziums are considered.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 50–54, January, 1995.     

Influence of direct electric current on the processes of contact fusion in the bismuth-tellurium system

We have investigated contact fusion (CF) in the Bi-Te binary system with a complex state diagram under different programs of heating the contact of specimens in the current and currentless regimes. CF at temperatures below the fusion temperature of the lowest eutectics has been revealed. It has been established that the known state diagram of the Bi-Te system is metastable and, depending on the contact heating rate, the CF processes proceed differently. It has been shown that the values and directions of the direct current passed through the contacts of Bi and Te specimens can control the phase-formation processes and the CF kinetics. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 6, pp. 34–41, November–December, 2005.     

The development of spatial structure in an ionic chemical system induced by applied electric fields

The spatio-temporal structures that can arise in an ionic chemical system with a cubic autocatalytic reaction step (Gray-Scott kinetics) in the presence of an applied electric field are described. A linear stability analysis of the resulting reaction-diffusion-advection system, with different diffusion coefficients and consequently different electrochemical migration rates for the reacting species, suggests the possibility of both convective structures ('DIFICI') and Turing patterns (as well as interaction between them). The detailed linear analysis determines the domain of existence of these features in parameter space, the predictions from which are confirmed by extensive numerical simulations. These reveal that a wide variety of propagating structures can be sustained by the system, depending on the electric field strength and whether the ratio of diffusion coefficients of autocatalyst and substrate is above or below the critical values for Turing bifurcations.     

Degradation of aldrin in adsorbed system using advanced oxidation processes: comparison of the treatment methods

In this study, Fenton, UV/Fenton, UV/H2O2, UV/Fe2+ advanced oxidation processes have been applied for degradation of aldrin adsorbed on Na-montmorillonitte and activated carbon. Aldrin adsorbed on Na-montmorillonitte was degraded more efficiently than that of on activated carbon. For example, in UV/Fenton technique 95% of aldrin was removed from Na-montmorillonitte while 50% degradation was observed on activated carbon. Degradation of aldrin adsorbed on Na-montmorillonitte has also been achieved effectively using UV/Fe2+ technique despite the absence of H2O2. All AOPs but Fenton have been observed nearly equally effective for degradation of aldrin on Na-montmorillonitte sorbent. Fenton reaction exhibited least activity in degradation aldrin adsorbed on Na-montmorillonitte. The experiments with activated carbon sorbent indicated that phenyl groups in activated carbon structure and aldrin molecules exhibited competitive behavior on reaction with OH* radicals. The results of infrared spectroscopy support this assumption. The degradation efficiency of aldrin using activated carbon sorbent was determined in the following order: UV/Fenton > UV/H2O2 > Fenton > UV/Fe2+.     

Degradation and detoxification of formaline wastewater by advanced oxidation processes

In this study, advanced oxidation processes (AOPs) utilizing the combinations of UV/H(2)O(2), Fenton, photo-Fenton and the combination of Fenton/photo-Fenton reactions were investigated in lab-scale experiments for the degradation of formaline wastewater. The studied toxic chemicals were formaldehyde and methanol in mixture solution, so-called formalin, which is the embalming agent in mortuaries. The experimental results showed that the photo-Fenton process was the most effective treatment process among the studied AOPs. Pseudo-first-order degradation rate constants of formaldehyde and methanol were obtained from batch experimental data. In the combination of Fenton/photo-Fenton reactions, the results show that applying UV light at an early stage of the reaction might not be necessary for a speedy oxidation reaction of the Fenton process. With Fenton and photo-Fenton processes, mineralization of formaline wastewater can be achieved, as no residual TOC is detected in the effluent after the reaction period. It is suggested that Fenton and photo-Fenton processes are viable techniques for the formaline wastewater treatment as they were able to provide high degradation of formaldehyde and methanol with relatively low toxicity of the by-products in the effluent.     

Breakage of rocks by pulsed electric discharge at elevated pressures and temperatures

The process of electric-pulse-induced breakage of sandstone, limestone, and granite at elevated pressures (up to 350 atm) and temperatures (up to 110°C) has been studied. The dependences of the material fracture depth, breakage output, and specific energy consumption on the temperature and pressure are determined.     

Suppressing pulsed microwave signals in a nonlinear spin wave interferometer

The suppression of S-band microwave pulses in a nonlinear spin wave interferometer was experimentally studied for the first time. The microwave interferometer employed a nonlinear spin wave phase shifter based on an yttrium iron garnet film. A signal representing a periodic sequence of rectangular pulses with a power of up to 2.5 mW passes through the nonlinear interferometer without distortion, while an increase in the pulse power to 13.8 mW results in virtually complete suppression of the pulsed signal.     

Non-radiation induced signals in TL dosimetry

One source of background signals, which are non-radiation related, is the reader system and it includes dark current, external contaminants and electronic spikes. These factors can induce signals equivalent to several hundredths of mSv. Mostly, the effects are minimised by proper design of the TLD reader, but some effects are dependent on proper operation of the system. The other main group of background signals originates in the TL crystal and is due to tribothermoluminescence, dirt, chemical reactions and stimulation by visible or UV light. These factors can have a significant contribution, equivalent to over several mSv, depending on whether the crystal is bare or protected by PTFE. Working in clean environments, monitoring continuously the glow curves and performing glow curve deconvolution are suggested to minimise non-radiation induced spurious signals.     

Information-measuring system for investigating by pulsed neutron probing

The structure and operating principle of a system for determining the limits of oil-bearing strata by the pulsed neutron-gamma and oxygen activation logging method are considered. A system for automatically stabilizing the yield of a neutron generator is analyzed. An algorithm for estimating the damping decrement of a flux of thermal neutrons in the region of the borehole space is given.Translated from Izmeritel'naya Tekhnika, No. 3, pp. 56–58, March, 1995.     

Nonequilibrium solidification effects induced by a pulsed magnetic field in ionic crystals

A digital DTA study of the process of solidification in KCl pretreated in a weak pulsed magnetic field (PMF) reveals a latent decrease in the enthalpy of solidification, followed by recovery of the initial state 144 h after the treatment. A sharp drop in the enthalpy of solidification observed 72 h after the PMF treatment gives rise to an additional relaxation process (postsolidification effect) revealed by a long-term fluctuational evolution of dissipated heat. According to the X-ray diffraction data, the PMF action upon KCl induces an intracrystalline transformation manifested by a small decrease in the lattice parameter and a sharp increase in the reflection intensity.