The stability constants of highly concentrated copper(II)-lactate alkaline aqueous solutions for Cu 2 O electrodeposition were determined by factor analysis of UV-vis absorption spectra. The stability constant is 10 7.05 ± 0.05 for the chemical equilibrium expression CuL 2 + OH-= Cu(H-1 L)L-+ H 2 O, while that for the chemical equilibrium expression Cu(H-1 L)L-+ OH-= Cu(H-1 L) 2 2-+ H 2 O is 10 5.05 ± 0.05 ; here, Lis the lactate ion (CH 3 CH(OH)COO-) and H-1 L 2is the deprotonated lactate ion (CH 3 CH(O-)COO-). By refining the potential-pH and pH speciation diagrams for the Cu-lactate-H 2 O system, it appears that the pH dependence of the preferential orientation of Cu 2 O is due to differences in the dissolved species.

No abstract