Ionic conductivity of Ln_4Zr_3O_(12) solid electrolytes synthesized by mechanochemistry

摘要

To explore their possible application as solid electrolytes in Solid Oxide Fuel Cells (SOFC), this contribution presents the synthesis, characterization and electrical properties of Ln(4)Zr(3)O(12) (Ln = Y, Ho, Er and Yb) zirconates. All samples were obtained by mechanical milling and their electrical properties were analyzed as a function of frequency and temperature, by using impedance spectroscopy. Our results show that defective fluorite-type zirconates might be successfully obtained after milling stoichiometric mixtures of the corresponding oxides, for 30-40 h in a planetary mill. Such structural form persists even after firing the as-prepared Y, Ho and Er zirconates, at very high temperatures (1500 degrees C); whereas, Yb4Zr3O12 shows a transition to a rhombohedral delta-phase on firing. Ionic conductivity (sigma) values obtained for all compositions at 700 degrees C (including fluorites and delta-phase), are comparable to those reported for similar ionic conductors, and within the 10(.-3.82) to 10(-613) S cm(-1) range. Higher sigma values were obtained for those zirconates preserving the disordered fluorite-type structure after firing. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.