Study Of Ion Diffusion Research Articles

(Invited) Harnessing the Architectural Power of Ionics: Electrolytically Formed Batteries

Ion diffusion represents the core challenge and a chronic weak link relative to the transport of its parallel counterpart, the electron. As such, decades of ground breaking work has been focused on the study of ion diffusion in various phases and interphases to improve transport properties. The fundamental challenge of ionics relates to the transport of charged mass, and as such, will always be inferior and lowly to that of the electron. In this paper we explore how the anchor of mass transport which limits ion diffusion enables ions to do what electrons cannot, create structure. This paper explores the power of ionics to enable the electrolytic formation of batteries from very simple structures and the feasibility to harness such power in formats that are not easily addressed by batteries of today. We will discuss this concept using various halide chemistries from our initial reports on iodide ion approximately a decade ago to the more challenging fluoride Ion.

Study of ion diffusion in oxidation films grown on a model Fe–15%Cr alloy

Chromium, oxygen and iron ion diffusivities were determined in thermally grown natural chromia layer on a model Fe–15wt.%Cr alloy in the temperature range from 750°C to 900°C, in air atmosphere. The stable isotopes 18O, 54Cr and 57Fe were used as oxygen, chromium and iron tracers, respectively, and the diffusion profiles were established by secondary ion mass spectrometry (SIMS). Oxygen bulk, effective and grain boundary diffusivities are lower than the corresponding chromium or iron diffusivities, while the iron diffusivities are greater than the chromium ones. Grain boundary is a fast path for chromium, iron and oxygen ion diffusions in natural chromia layer grown on the Fe–15%Cr alloy. Therefore, the oxidation rate of the Fe–Cr alloy is mainly controlled by grain boundary ion diffusion. The values of the calculated parabolic oxidation constant, according to Wagner's theory, are close to the experimental ones, assuming that chromium and oxygen ion diffusions in chromia grown on the Fe–15%Cr alloy occur in an extrinsic regime. Moreover, chromium ion diffusion plays the main role on the oxidation of the Fe–15%Cr being sufficiently large to maintain the oxidation rate of the alloy.

Study of Ion Diffusion in Ion-exchange Resins by an Autoradiographic Method

ACCORDING to Boyd1, the progress of exchange processes on ion-exchange resins is determined either by film diffusion or by the rate of grain diffusion; and it can be decided from the characteristic data for the system2,3 which process determines the rate in given experimental conditions. The conditions determining the two mechanisms are given by the relations illustrationillustration where c is the capacity of the resin in g equivalents ml.−1, D is the diffusion constant for the resin phase, cL is the concentration of the solution, DL is the constant for the solution diffusion, α is the selectivity coefficient, r is the radius of the resin grain and δ is the thickness of the adhesion layer. Open image in new window Open image in new window