methods of making metal oxide articles , preferably iron oxide articles , and articles thereby produced . the method comprises the steps of slightly pressing powder to a compact , the powder consisting essentially of a first oxide of the metal ; and subjecting the compact to a heat treatment that causes the powder to sinter into a unitary body and results in the transformation of at least a portion of the first oxide to a second oxide by oxidation or deoxidation during the heat treatment . in disclosed embodiments , the heat treatment is conducted either in air at atmospheric pressure or at a subatmospheric pressure . the method optionally includes more heating / cooling steps resulting in additional oxidation / deoxidation cycles . sintered iron oxide articles of the invention have high mechanical strengths and interconnected pore structures , providing for efficient filtering of liquids and gases .