Papers by Keyword: Complex Formation

Abstract: The study explores the thermo-physical properties of complex binary liquid potassium-lead alloy at temperature 848 K as a function of concentration by considering complex using different model equations. The Quasi Chemical approximation and the R-K equation are used to investigate features such as free energy, heat of mixing, chemical activity, and concentration fluctuation in the long wave limit at temperature of 848 K. However, at 900 K and 1000 K, these are exclusively examined using the R-K equation. The temperature dependent exponential interaction parameters proposed by Kaptay are taken into account in the RK equation. The study goes on to look at the alloy's viscosity and surface tension using the Budai-Benko-Kaptay model and the Kaptay's improved derivation of Butler equation. The mixing nature of the system is investigated in depth, with a focus on the interaction energy parameters between the alloy's surrounding atoms. The work investigates the fact that the liquid alloy has a moderately interacting as well as ordering character throughout a whole concentration range, and the computed theoretical thermodynamic facts are in reasonable agreement with the corresponding experimental data at 848 K. At greater temperatures, the alloy's tendency goes from ordering to segregating. The alloy's viscosity and surface tension decrease as the temperature rises.

Abstract: The influence of fibrous and solid granulated fillers on the rheological and surface properties of the polymer compositions on the basis of polyvinyl alcohol and Na-carboxymethyl cellulose is demonstrated. The polymer complexes with Na-carboxymethyl cellulose and sodium tetraborate additions and the compositions filled with polypropylene, polyethylene terephthalate and quartz sand are obtained and comparative assessment of the properties of studied polymer composites have been made. Polymer compositions with quartz sand, synthetic and plant fibrous fillers increase the effective viscosity, elasticity modulus and decrease the adhesive strength of all compositions based well on carboxymethyl cellulose and polyvinyl alcohol. The sodium tetraborate introduction promotes the formation of the composites surface with the lesser adhesive strength.

Abstract: In the present article the authors make an attempt to survey briefly the main landmarks of the GBD, to set off the most interesting results of the last years, to underline some gaps between expected and observed experimental data and to direct possible ways of their explanation.

Abstract: Thermodynamic and kinetic models are developed for grain boundary segregation and diffusion with regards to the possible complexes formation in grain boundary. The equilibrium state for ideal solutions can be described by the equilibrium constants b and K. The first corresponds to the pure segregation, i.e. the exchange A and B atoms between grain boundary and the bulk. The second represents the equilibrium of the reaction of the complexes formation in grain boundary. The segregation isotherm and diffusion profiles are calculated. It is shown that both b and K equilibrium constants define completely dependence of the total grain boundary concentration of B atoms on the bulk concentration and distribution of B atoms between two states: free (pure exchange) and tied (in the complexes). Segregation in both forms (free B atoms and tied B atoms) decreases grain boundary diffusivity in comparison with the absence of segregation.

Abstract: Electronic grade diamond is usually grown by Microwave Plasma assisted CVD from a hydrogen rich CH4/H2 mixture, hence hydrogen is likely to be incorporated during growth. It may thus affect the properties of the material. In this work, we present the state of the art on the understanding of the diffusion properties of hydrogen and of the hydrogen-dopant interactions in diamond. First, we show the existence of strong interactions between H and boron dopants in diamond. The formation of H-acceptor pairs results in the passivation of the acceptors. Further, we show that an excess of hydrogen in selected boron-doped diamond epitaxial layers can result in the creation of H and boron-containing donors with a ionization energy of 0.36 eV (about half the ionization energy of phosphorus). At 300 K, the n-type conductivity of hydrogenated borondoped diamond is several orders of magnitude higher than the conductivity of phosphorus-doped diamond. The formation process of these new donors is discussed.

Abstract: The n-type doping of diamond with phosphorus suffers from defects reducing the electron mobilities and inducing some degree of compensation. In addition, the relatively high ionization energy (0.6 eV) of phosphorus severely limits the electrical activity of the dopants. Here, we present two recent advances of the n-type doping of diamond. One is based on the significant reduction of the compensation ratio of highly compensated phosphorus-doped diamond by thermal annealings. The second one presents the possibility of converting p-type boron-doped diamond into n-type by deuterium diffusion and formation of deuterium-related shallow donors with ionization energy of 0.33 eV.