“Smoothening Mechanism of Thiourea on Silver Electrodeposition. Real time Imaging of the Growth Front Evolution”.

O. AZZARONI; P.L. SCHILARDI; R.C. SALVAREZZA; A.J. ARVIA.

LANGMUIR

Año: 1999 p. 1508 - 1514

0743-7463

Ag electrodeposits were grown on a polycrystalline Ag cathode at either 0.01 or 1mA cm-2 from aqueous 5 10-3 M Ag2SO4 + 10-2 M H2SO4 + 0.5 M Na2SO4, in the absence and presence of different amounts of thiourea (TU). The cathode/solution interface evolution in a quasi-bidimensional electrochemical cell was followed with a video microscope imaging system. From TU-free solution a nodular morphology at 0.01 mA cm-2 and a branched morphology at 1 mA cm-2 were observed. At 0.01 mA cm-2 the presence of TU drove the interface motion to a stable roughness regime by suppressing the nucleation and growth of instabilities. Accordingly, the characteristics of the growth front were consistent with the predictions of the Edwards-Wilkinson equation for the interface motion. At 1 mA cm-2, those electrodeposits grown in the presence of TU showed a decrease in both the nucleation and growth rates of instabilities, although they were not fully suppressed