Effect of orientation of initially formed grains on the final morphology of electrodeposited lead

Abstract

The processes of Pb electrodeposition under diffusion control were examined by scanning electron microscopy (SEM) of the formed crystals. The orientation of grains of hexagonal shape formed in the initial stage of electrodeposition strongly affected the final morphology of the Pb crystals. The formation of Pb crystals of the different shape from the same initial shape was discussed in terms of the effect of orientation of initially formed grains on the type of diffusion control. A spherical diffusion layer was formed around the tip of the hexagonal-shaped grain oriented with its tip towards the bulk solution that led to the formation of elongated crystals in the growth process. On the other hand, a cylindrical type of diffusion was responsible for the growth of hexagonal-shaped grains oriented with the lateral side towards the bulk solution. Pb crystals with well-defined sides parallel to the surface area of the macroelectrode were formed under this type of diffusion.

Estimation of the exchange current density and comparative analysis of morphology of electrochemically produced lead and zinc deposits

“…The procedure for recording of the polarization curves is described elsewhere. 26,27 For morphological analysis, Zn and Pb were electrodeposited galvanostatically at current densities (j) which corresponded to 0.25j L and 0.50j L . These current densities were 0.15 and 0.30 mA cm -2 (Zn), and 0.065 and 0.13 mA cm -2 (Pb).…”

Fundamental aspects of lead electrodeposition processes: Nucleation and growth

“…Osim formiranja heksagonalnih kristala u početnoj fazi taloženja, na krajnju morfologiju olova utiče i njihova orijentacija ka dubini rastvora [25]. Premda se proces taloženja odvija pod difuzionom kontrolom na makroelektrodi, krajnja morfologija elektrohemijski istaloženog olova je određena lokalnim tipom difuzionog polja koje se formira oko vrhova i bočnih ivica rastućih heksagonalnih kristala [26].…”

“…Međutim, ako je kristal heksagonalnog oblika orijentisan svojim vrhom ka dubini rastvora (slika 6e; deo označen sa B), tada sferični difuzioni sloj se formira oko vrha, dok cilindrični difuzioni sloj oko bočnih ivica. Pošto je brzina rasta u uslovima sferične difuzije veća nego u uslovima cilindrične difuzije, tada izduženi kristali (prekursori dendrita) ili dendriti su formirani u procesu rasta [25,26]. Igličaste forme (slike 7d i e) su još jedna od tipičnih formi koje karakterišu procese elektrohemijskog taloženja olova.…”

The shape of the polarization curve and diagnostic criteria for control of the metal electrodeposition process

“…The experimental procedure for recording the Pb polarization curves is given in the literature. 13,14 For the morphological analysis of deposits, lead, copper and zinc were electrodeposited potentiostatically at overpotentials of 10, 50 and 100 mV (Pb), 90, 210, 650 and 1000 mV (Cu) and 45 and 100 mV (Zn). The times of electrodeposition are indicated in the Figure captions.…”