US Patent 7498058 Substrates coated with a polycrystalline functional coating

A method for forming a coated substrate is disclosed. The method includes depositing an undercoating layer on a substrate; and depositing a functional coating on the undercoating layer, the functional coating comprising at least one material that can be present in at least two crystal structures, wherein the at least two crystal structures are present at and exposed surface of the functional coating, wherein the undercoating layer comprises at least two different materials wherein a first material at the exposed surface provides a first surface area and a second different material at the exposed surface provides a second surface area.