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).