The Anodic Oxides of Lead

The anodic oxides formed on lead under varying potential and pH were identified by x- ray and electron diffraction. Pure lead specimens were anodized at selected constant potentials to develop anodic coatings of sufficient hickness to give strong x- ray patterns. The domains of occurrence of: a and / ~ PbO~, yel low and red PbO, and the intermediate oxides, Pb30,, and PbOx were deter-mined for acid and alkal ine electrolytes. The intermediate oxides are not be-l ieved to be direct anodic oxides, but to represent chemical reaction products. The occurrence of certain of the oxides may be attr ibutable to an init ial elec-trochemical oxidation f water. The identifications have been presented in po-tent ia l-pH phase diagrams. Coinc ident w i th a s tudy of the posit ive gr id cor-ros ion of the lead-acid storage cell, the anodic oxides formed on lead at various potentials in H~SO, were identified by x-ray and electron diffraction (1, 2)