Room-temperature synthesis and conductivity of the pyrochlore type Dy-2(Ti1-yZry)(2)O-7 (0 <= y <= 1) solid solution

摘要

Different compositions in a solid solution of general formula Dy-2(Ti1-yZry)(2)O-7, showing high oxygen ion conductivity, have been successfully prepared at room temperature via mechanochemical synthesis. Stoichiometric mixtures of the constituent oxides were dry milled together in a planetary ball mill by using zirconia vials and balls. Chemical changes in the powder mixtures as a function of composition and milling time were followed by X-ray diffraction and revealed that, in all cases and after milling for 19 h, the powder mixtures consisted of a single phase. Electrical properties were measured on sintered pellets as a function of frequency, temperature and zirconium content, revealing an increase in conductivity of more than one order of magnitude for y >= 0.4, which, as observed in the similar Y-2(Ti1-yZry)(2)O-7, has been related with the onset of disordering of the anion sublattice. Despite increasing structural disorder with increasing Zr content, conductivity remains almost constant for y > 0.6, reaching a maximum value of similar to 5 x 10(-3) for Dy2Zr2O7 at 900 degrees C. (C) 2005 Elsevier Inc. All rights reserved.