Potentiostatic versus galvanostatic electrodeposition of nanocrystalline Al–Mg alloy powders

Abstract

Nanocrystalline supersaturated dendritic Al-Mg powders were electrodeposited using potentiostatic and galvanostatic techniques under equal-charge conditions. In potentiostatic deposition morphology depended on applied potential: featherlike at lower and globular at higher potentials. Galvanostatic deposits yielded both morphologies at any current density. Morphological evolution was observed in galvanostatic deposits from featherlike to globular. Independent of deposition technique facecentered cubic Al(+Mg) phase with ∼7 atom% Mg (featherlike) with/without ∼20 atom%Mg (smooth globular) composition formed at lower applied/realized potentials (or deposition rates). Higher applied/realized potentials showed hexagonal close packed Mg(+Al) phase with ∼80 atom% Mg (rough globules) over smooth globules. Potentiostatic and galvanostatic deposits were compared for their morphologies, phases, and compositions.

Electrodeposition Fabrication of Chalcogenide Thin Films for Photovoltaic Applications

“…Galvanostatic deposition can be useful in applications where no control over morphology is necessary. The potentiostatic deposition technique, however, was mainly used to investigate the mechanisms of deposition and morphology formation [34]. The deposition of chalcogenide films for the photovoltaic device applications has been predominantly adopting the potentiostatic mode in view of the need of a morphology control for the films and also for the reason that the potentiostatic mode is more suitable for depositing multiple elements simultaneously, i.e., the so-called co-deposition that will be introduced in the following sections.…”

Evolution of Morphology and Microstructure in Electrodeposited Nanocrystalline Al–Mg Alloy Dendrites

“…The global diffusion layer thickness was estimated for the rotating-cylinder-cell-setup using equation (1) . The estimated value of the diffusion layer thickness is 328 µm which is larger than the average length of the dendrites (~250 µm) [20]. The dendrites were composed of several different morphologies assembled in stacks.…”

“…Similar to local potentials these local current densities are very difficult to measure. However, we could estimate the current density around the tips of the feather-like morphology [20]. The tips of the feather-like morphology experience current densities both at their tips and sides according to Equations (2) and (3) respectively [9]:…”

Nanostructure stabilization in electrodeposited Al–Mg dendrites

“…We electrodeposited nanocrystalline supersaturated metastable Al−Mg dendrites for H2−storage [12]. By thorough analyses we understood the Al-Mg electrodeposition scheme [13]; internal [14], external morphological [12], microstructural [15], compositional [16,17], textural [18], phase [19] features; and the dendritic growth mechanisms [20,21]. [12].…”