Diffusion and phase transformations in spark plasma synthesized and sintered CU-V2O5 couples

摘要

Fast diffusion of Cu into V2O5 at 520 degrees C is studied in CU-V2O5 diffusion couples sintered by spark plasma sintering. The impact, on the diffusion profiles, of phase transformations and of variations of the diffusion coefficient with Cu concentration is discussed. From the pure Cu source, two phases are observed to spread, leading to a "two-step-like" shape of the diffusion profiles. In the more concentrated phase (phase epsilon), the diffusion coefficient D of Cu is approximate to 3 x 10(-8) m(2)/s. This is a remarkably high value, of the same order of magnitude as self-diffusion in liquid metals. In the less concentrated phase (phase beta'), D is lower than in epsilon. This is due to the differences in the diffusion mechanisms of Cu in these two phases: two dimensional in e and one dimensional in beta'. In beta', D strongly depends on Cu concentration. This is in good agreement with computer simulations reported in the literature. (C) 2008 Elsevier Inc. All rights reserved.