A sonication step was applied to the solution at 35kHz for 10 min to break apart possible aggregates formed in solution.Finally,colloidal suspentions of pure oxide phases were stabilized in an azeotrope solution composed of 96 vol.% absolute ethanol mixed with ultra-pure water after centrifugation of thebpeptized compounds before dip-coating with a NIMA DC small dip-coater from Lot-Oriel(withdrawal rate of 200mm/min) for thin film preparation.