Defects and Diffusion in Ceramics IX

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Authors: Khaled Habib, K. Al-Muhanna, F. Al-Sabti, A. Al-Arbeed
Abstract: In the present work, the electrochemical behavior and the oxide barrier-film thickness of anodized aluminum-magnesium (Al-Mg) alloy were determined in the as-received and annealed conditions by using electrochemical techniques. Electrochemical parameters such as the polarization resistance, solution resistance, alternating-current (AC) impedance, and the doublelayer capacitance of the anodized Al-Mg alloy were determined in boric acid solutions, with 0 to 10%H3BO3, by using electrochemical impedance spectroscopic (EIS) methods. The oxide barrierfilm thickness of the anodized Al-Mg alloy was then deduced, from the electrochemical parameters obtained, as a function of the boric acid concentration (0 to 10%H3BO3). The optimum thickness of the oxide barrier-film was detected for as received samples (1.17nm) and for annealed samples (1.22nm) at a boric acid concentration of 4%H3BO3.
Authors: Dao Khac An
Abstract: This paper summarizes some of the main results obtained concerning aspects of anomalous single-dopant diffusion and the simultaneous diffusion of multi-diffusion species in semiconductors. Some important explanations of theoretical/practical aspects have been investigated, such as anomalous phenomena, general diffusivity expressions, general non-linear diffusion equations, modified Arrhenius equations and lowered activation energy have been offered in the case of the anomalous fast diffusion for single-dopant diffusion process. Indeed, a single diffusion process is always a complex system involving many interacting factors; conventional diffusion theory could not be applied to its investigation. The author has also investigated a system of multi-diffusion species with mutual interactions between them. More concretely, irreversible thermodynamics theory was used to investigate the simultaneous diffusion of dopants (As, B) and point defects (V, I) in Si semiconductors. Some attempts at theory development were made, such as setting up a system of general diffusion equations for the simultaneous diffusion of multi-diffusion species involving mutual interactions between them, such as the pair association and disassociation mechanisms which predominated during the simultaneous diffusion of dopants and point defects. The paper then gives some primary results of the numerical solution of distributions of dopants (B, As) and point defects (V, I) in Si semiconductor, using irreversible thermodynamics theory. Finally, several applications of simultaneous diffusion to semiconductor technology devices are also offered.
Authors: J.C. de Lima, L.A. Santos, S.M. Souza, T.A. Grandi, C.E.M. Campos
Authors: L.I. Erokhin
Abstract: A matrix method for description of some thermodynamic properties in multicomponent alloys in explicit form has been proposed. It has been found that the method for determining thermodynamic properties from the cross-section data allows to find the contribution of short-range ordering into the thermodynamic state of an imperfect alloy. Diffusion processes in alloys are formed both from purely kinetic migrations of particles and from the system's thermodynamic properties. A consequence of this fact is that the diffusion coefficients D in all systems except for perfect solid solutions include to factors being D = Lg , the second one is the thermodynamic factor directly related to the system's chemical potential. However direct experimental separation of these factors can easily be performed in binary systems only while in triple systems in is highly difficult let alone multicomponent systems. Experimental evaluation of the factors in multicomponent systems from short-range order's parameters [1] would allow to establish a relation between the system's thermodynamic properties which is highly important for further progress in multicomponent diffusion theory and for practical applications.

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