A 0.1 M FeCl3 aqueous solution was hydrothermally treated in a 1.5-dm3 stainless steel autoclave at varied temperatures (Th: 110-200 degrees C). Highly ordered cubic particles with uniform micropores 0.8 nm in diameter are produced at Th = 115 degrees C, although the cubic particles become less uniform with wide pore size distribution by raising the Th.
