Methods of forming an oxide are disclosed and include contacting a ruthenium-containing material with a tantalum-containing precursor and contacting the ruthenium-containing material with a vapor that includes water and optionally molecular hydrogen (H2). Articles including a first crystalline tantalum pentoxide and a second crystalline tantalum pentoxide on at least a portion of the first crystalline tantalum pentoxide, wherein the first tantalum pentoxide has a crystallographic orientation that is different than the crystallographic orientation of the second crystalline tantalum pentoxide, are also disclosed.