Strontium hafnate phases by anodic spark conversion

Abstract The preparation of strontium hafnate (SrHfO 3 ) phases by the technique of anodic spark conversion has been demonstrated. This method involves anodic hafnia (HfO 2 ) generated during the pre-spark anodization, and subsequent conversion of hafnia to strontium hafnate in the anodic spark regime. Hafnium, as a valve metal, forms a dense, pore-free, oxide barrier film, up to about 100 nm thickness, in aqueous electrolyte systems during potentiodynamic anodization. The high potential sparking reactions initiate the transformation of the monoclinic hafnia phase to the perovskite-type strontium hafnate phase. The anodic coatings generated and the microcrystalline hafnate phases were characterized by Raman spectroscopy and electron microscopy techniques (TEM/SADP) at different stages of the anodic conversion process.