Effect of the applied magnetic field on formation of complex polyaniline films

Formation of complex polyaniline (PANI) films with diamagnetic TCNQ and paramagnetic metal ion impurities cast under applied magnetic field was studied. It has been found that the applied magnetic field affects interaction of PANI chains with the impurities and induces formation of magnetically ordered regions in the complex film doped by paramagnetic metal ions in contrast to the reference film of the same composition but prepared under ambient conditions. The magnetically ordered regions have been observed directly by scanning magnetic force microscopy. It was found a correlation in distribution of the magnetically ordered regions and peculiarities of the surface relief of a film. Electronic absorption spectra and conductivity measurements showed that an applied stationary magnetic field can suppress the interaction of PANI chains and paramagnetic metal ions and lowers conductivity of the resulting complex film up to one order of magnitude as compared with the reference film. An alternating magnetic field was found to improve interaction of PANI and diamagnetic TCNQ molecules. The mechanisms of the magnetic field influence on the complex film formation are discussed.Comment: 15 pages, 10 figure

Nano- and micro-scale morghological defects in oxidized a-SiC: H thin films

Amorphous carbon rich a-SiC:H films were deposited on silicon substrates by RF-magnetron sputtering of SiC target in argon/methane gas mixture. The principal focus of this study was investigation of the effect of thermal oxidation on structure and morphology reconstruction in a-SiC:H amorphous network. The density of the films was varied over the range 1.6-2.2 g/cm2 by varying the magnetron discharge power. The local nano- and micro-scale surface morphology and chemical composition distribution were examined by atomic force microscopy, scanning electron microscopy equipped with Auger electron scanning system and optical profilometry. It was found that partial oxidation leads to local structure reconstruction accompanied by transformation of mechanical stresses from compressive to tensile. Formation of carbon-enriched nano- and micro-scale regions was observed after oxidation in low density samples. We attrribute these morphological defects to migration and precipitation of carbon species released in the process of oxidation of the SiC amorphous network. The mechanism of tensile stresses generation is also discussed.Science and Technology Center of Ukraine, project No. 5513, National Academy of Science project No. 2-2-15-28 and Arts et Métiers ParisTech (invited professor

Nano- and micro-scale morghological defects in oxidized a-SiC: H thin films

Amorphous carbon rich a-SiC:H films were deposited on silicon substrates by RF-magnetron sputtering of SiC target in argon/methane gas mixture. The principal focus of this study was investigation of the effect of thermal oxidation on structure and morphology reconstruction in a-SiC:H amorphous network. The density of the films was varied over the range 1.6-2.2 g/cm2 by varying the magnetron discharge power. The local nano- and micro-scale surface morphology and chemical composition distribution were examined by atomic force microscopy, scanning electron microscopy equipped with Auger electron scanning system and optical profilometry. It was found that partial oxidation leads to local structure reconstruction accompanied by transformation of mechanical stresses from compressive to tensile. Formation of carbon-enriched nano- and micro-scale regions was observed after oxidation in low density samples. We attrribute these morphological defects to migration and precipitation of carbon species released in the process of oxidation of the SiC amorphous network. The mechanism of tensile stresses generation is also discussed.Science and Technology Center of Ukraine, project No. 5513, National Academy of Science project No. 2-2-15-28 and Arts et Métiers ParisTech (invited professor

On the Prospects of Using Metallic Glasses for In-vessel Mirrors for Plasma Diagnostics in ITER

This chapter reviews main results obtained on mirror-like samples made of several grades of bulk metallic glasses (BMG). Experiments were carried out under simulated conditions typical for the operation of plasma facing in-vessel mirrors of optical plasma diagnostics in fusion reactor ITER. Bombardment with D0 and T0 atoms radiated from burning plasma was predicted to be the main reason for the degradation of optical properties of such mirrors. Therefore, to simulate the behavior of mirrors in ITER, mirror-like samples were subjected to bombardment by ions of deuterium plasma with fixed or wide energy distribution. The effects of ion bombardment on optical properties, development of roughness, uptake of deuterium, appearance of blisters, and manifestation of some chemical processes are presented and discussed

Method of Functioning of Intelligent Agents, Designed to Solve Action Planning Problems Based on Ontological Approach

The problem of operation of intelligent agents of action planning with the use of ontological approach was studied. Operation of intelligent agents is possible based on the knowledge of the subject-area, in other words, the knowledge base is used. Ontologies became the standard of knowledge base. Therefore, there arises the problem of development of methods and means of operation of intelligent systems based on ontologies, in particular intelligent agents of action planning.The method of functioning of intelligent agents of action planning based on ontologies was developed. For this purpose, weights of importance of concepts and relationships were introduced to the structure of ontology. These weights are used for finding a path in the space of states. The space of states itself is built by using the language of requests to ontology. Optimization problem, which assigns the rational behavior of an intelligent agent, is two-criterial. To solve it, we chose the method of the main component, if objective functions may be evaluated, or the method of complex criterion, if these functions are impossible to evaluate.Dimensionality of the space of states depends on the completeness of the ontology, and behavior effectiveness of an intelligent agent depends on the relevance of ontology. With this aim, in the course of automated development of ontology, we developed a method for evaluation of reliability of information sources that are used for developing ontologies. As a result of the studies, it was found that this approach allows us to increase operational efficiency of intelligent agents, if the process of ontology development is relevant to the needs of a subject domain.The developed approach may serve as a base for constructing a unified methodology for development of intelligent agents of action planning if ontology of a subject domain is the central component of this software comple

Electron Accumulation Tuning by Surface-to-Volume Scaling of Nanostructured InN Grown on GaN(001) for Narrow-Bandgap Optoelectronics

The existence of an uncontrolled electron accumulation layer near the surface of InN thin films is an obstacle for the development of reliable InN-based devices for use in narrow-bandgap optoelectronics. In this article, we show that this can be regulated by modulating the surface of the InN grown on GaN(001). By increasing the surface-to-volume ratio, we can demonstrate a reduction in the surface carrier concentration from ∼1018 to ∼1017 cm–3. These controlled changes are despite the idea that donor-type surface states, which contribute to conduction band electrons are reported to be the main origin of the surface charge density. Additionally, by evaluating the surface carrier concentration through modeling of photoluminescence (PL) spectroscopy, we have found a failure of the Burstein–Moss theory. Conversely, modeling of the longitudinal optical phonon–plasmon coupled modes measured using Raman spectroscopy, simulations of InN structures using the k·p method, and Hall effect measurements, where possible, showed an excellent correlation of the surface electron concentrations. The large inhomogeneous broadening in the PL, which overwhelms any broadening due to the Burstein–Moss effect, is understood to be the result of varying Stark shifts due to varying strain throughout high surface-to-volume nanostructures, which dramatically affects the spatially indirect nature of the electron–hole recombination. Finally, our findings demonstrate how the electron population of 2D and 3D InN nanostructures can be tuned by structural features, such as porosity and/or the surface-to-volume ratio