121Sb Mössbauer spectra of M or A-doped antimonic acid (M = Ta and Nb, A = Bi and Y) fine nanoparticles prepared by soft chemical solution process

Abstract

121Sb Mössbauer spectroscopic studies on the pyrochlore-type M or A-doped antimonic acids (M = Ta and Nb, A = Bi and Y) nanoparticles were carried out at 12 K in order to determine the oxidation state of Sb and also find more useful information for making clear the detail mechanisms of the photocatalytic property and the proton conductivity. The 121Sb Mössbauer results indicated that all of Sb were Sb5+ in HSb1−xMxO3·nH2O (M = Ta and Nb) which Sb was partially substituted by M, however, small amount of Sb were Sb3+ in H1−3xAxSbO3·nH2O (A = Bi and Y) which H was partially substituted by A. The amounts of Sb3+ in the Bi-containing material were clearly larger than that in the Y-containing material. The photocatalytic properties and the proton conductivities of the pure and M or A-containing materials were discussed in relation to their 121Sb Mössbauer parameters, especially isomer shift (δ) and quadrupole coupling constant (e2qQ).