FeSbO4 phase formed at the surface of antimony(V) oxide grafted on silica gel

Abstract

The FeSbO₄ phase on antimony(v) oxide grafted onto a silica gel surface was obtained by two different ways: (i) by immersing the material, Sb/SiO₂, in an aqueous solution of iron(III) followed by heat treatment at 423 K or (ii) by immersing the material in a solution of Fe(CO)₅ in CCl₄ followed by further hydrolysis and heat treatment: for treatment at 423 K, the separated phase Fe₂O₃ is observed while a new phase, FeSbO₄, is formed upon heating the sample at 1073 K. In both cases an excess of antimony(V), in relation to iron(III), was found on the surface. This fact was interpreted as a result of antimony(v) migration from the internal to the external surface of the matrix when method (i) was used, and as due to a migration of iron(III) in the opposite direction, when the material was obtained by method (ii).