Nucleation and Morphology Studies of Aluminum Deposited from an Ambient‐Temperature Chloroaluminate Molten Salt

Aluminum deposition from (1‐methyl‐3‐ethylimidazolium chloride) has been studied employing an inverted optical microscope to perform in situ optical observations during the deposition process at a 250 μm diam tungsten electrode. Thin, continuous aluminum coatings with nuclei (or cluster) sizes below optical microscopic resolution are produced from a 1.1:1.0 molten salt using constant potential deposition at potentials ≤ −0.2 V vs. an Al(III)/Al reference electrode. At less negative potentials, the microscopic structure consists of larger (>0.5 μm), optically resolved nuclei. Analysis of chronoamperograms indicate that the deposition process involves progressive nucleation with diffusion‐controlled growth of the three‐dimensional nuclei. Calculated nuclear site densities and average nuclei sizes are in agreement with optical and electron microscope images.