Electrochemical Synthesis of Ln2Cr3O12·7H2O (Ln = La, Pr, Nd)

Rare-earth chromates Ln2Cr3O12 · 7H2O (Ln = La, Pr, Nd) have been electrosynthesized by cathodic reduction of acidified aqueous solutions of La(NO3)3 and (NH4)2Cr2O7 under both galvanostatic and potentiostatic conditions. The crystalline products, which have been characterized by X-ray diffraction, IR, and TG, are identical to the products obtained from conventional hydrothermal synthesis. Under galvanostatic conditions, these materials have been stabilized as adherent coatings on stainless steel substrates. These coatings, upon thermal treatment, yield coatings of perovskite oxides of the type LnCrO3. This novel method can be adapted for the fabrication of corrosion protective coatings for high temperature applications.