Thermal and electrical properties of Ba2In2O5 substituted for In-site by rare earth elements

Ba2(In1-xRx)2O5 (x=0, 0.05, 0.1; R=Sc, Lu, Yb, Y, Dy, Gd, Sm) were synthesized by a solid-state reaction method, and all the prepared samples were confirmed to be a single phase by XRD. The lattice volume increased with increasing ionic radius of the substituents, and the slope in the plot of the lattice volume against the ionic radius was changed around the ionic radius of Y3+ or Dy3+. The order-disorder transition temperatures of oxygen vacancies of all the prepared samples were determined by electrical conductivity measurement. The transition temperatures of the samples substituted by larger (or smaller) ions in the ionic radius than In ion were larger (smaller) than that of un-substituted Ba2In2O5, probably due to the preferred site of substituent to either octahedral InO6 site or tetrahedral InO4 site.