Preparation and Some Electrical Properties of Yttrium-Doped Antimonic Acids

Abstract

New kinds of yttrium-doped antimonic acid compounds with the compositional formula of H1-3xYxSbO3·nH2O (0 ≤ x ≤ 0.22, n = 0.5) were successfully synthesized by solution processing using the reaction of an aqueous hydrogen peroxide solution with antimony and yttrium alkoxides, i.e., Sb(O-iso-C3H7)3 and Y(O-iso-C3H7)3, respectively. It is recognized from TEM measurements that the resulting materials (x = 0 and 0.12) consist of fine crystals with a relatively uniform particle size of 40−50 nm. The Rietveld refinement based on X-ray diffraction data revealed that the Y atoms in the materials are present on an interstitial 16d site. The ionic transference numbers and proton conductivity were evaluated using ac and dc measurement methods. Consequently, it was found that the ionic transference numbers are over 0.98 regardless of the yttrium-doping degrees and that the proton conductivity is significantly enhanced by the yttrium doping; the conductivity at 20 °C is 8.3 × 10-5 and 3.8 × 10-3 S cm-1, respectively, for the pure material and the doped material (x = 0.12). The activation energies of 0.58 and 0.43 eV in the temperature range of 243−298 K are obtained for the pure material and the doped material (x = 0.12), respectively. Such variation in the proton conduction is qualitatively interpreted in terms of the strength of the hydrogen bonding between the oxygen atoms of the (Sb2O62-) frameworks and H2O or H3O+ species, which changes according to the yttrium doping.