Smooth crack-free targets for nuclear applications produced by molecular plating

Abstract

The production process of smooth and crack-free targets by means of constant current electrolysis in organic media, commonly known as molecular plating, was optimized. Using a Nd salt, i.e., [Nd(NO3)3·6H2O], as model electrolyte several constant current density electrolysis experiments were carried out to investigate the effects of different parameters, namely the plating solvent (isopropanol and isobutanol mixed together, pyridine, and N,N-dimethylformamide), the electrolyte concentration (0.11, 0.22, 0.44mM), the applied current density (0.17, 0.3, 0.7, and 1.3mA/cm2), and the surface roughness of the deposition substrates (12 and 24nm). Different environments (air and Ar) were used to dry the samples and the effects on the produced layers were investigated. The obtained deposits were characterized using γ-ray spectroscopy for determining Nd deposition yields, X-ray photoelectron spectroscopy for chemical analysis of the produced surfaces, radiographic imaging for surface homogeneity inspection, atomic force microscopy for surface roughness evaluation, and scanning electron microscopy for surface morphology investigation. The results allowed identifying the optimum parameters for the production of smooth and crack-free targets by means of molecular plating. The smoothest layers, which had an average RMS roughness of ca. 20nm and showed no cracks, were obtained using 0.22mM [Nd(NO3)3·6H2O] plated from N,N-dimethylformamide at current densities in the range of 0.3–0.7mA/cm2 on the smoothest deposition substrate available.