Electrodeposition of Cu2O coatings on stainless steel substrates -: Control over orientation and morphology

Oriented Cu2O coatings were grown on polycrystalline stainless steel substrates showing that oriented crystallization can be nucleated by processes other than epitaxy. Cu2O, deposited from alkaline Cu(II) lactate bath at pH 9 switches the growth direction from [100] to [110] on varying the bath composition. On decreasing the temperature from 65 to 55 degrees C the orientation switches back to [100]. At pH 12 a distinctive [111] orientation unaffected by the bath composition was observed. This shows the importance of a solution-based chemical approach to directing oriented crystallization through a kinetic pathway. This alternative approach is based on a complex interplay of a number of factors such as the stability constant of the precursor species, solubility of the product species, and degree of supersaturation of the bath as determined by the pH, temperature, and concentration. The distinct orientations depend on the crystal energetics and can be correlated to the observed morphology, thereby establishing a direct relationship between the textural properties at the nanometer level and the morphology at the micrometer level. The coatings were characterized by powder X-ray diffraction and scanning electron microscopy. (C) 2007 The Electrochemical Society.