The synthesis and electrical conductivity of novel mixed ionic and electronic conductors in the Gd₂GaSbO₇-Gd₂Zr₂O₇ solid solution

The synthesis and electrical conductivity of a novel solid solution pyrochlore Gd₂GaSbO₇-Gd₂Zr₂O₇ were studied as a function of x in Gd₂(GaSb)_1-xZr_2xO₇ (0 ≤ x ≤ 1). In this study, single phases with the pyrochlore structure were obtained in the range of x ≤ 0.2, while a garnet phase appeared as a minor second phase for x ≥ 0.3. In the x = 0.2 sample, evidence of the displacement of 48f oxygens towards the normally empty 8b site was suggested by Rietveld analysis. The total electrical conductivity of the pyrochlores was 2.6×10^-2 S/m for x = 0.0 and 6.0×10^-3 S/m for x = 0.2 at 1273 K, respectively. In addition, evidence for n-type semiconductivity was obtained for x = 0.2 under reducing conditions. Further studies are underway to identify the dominant carriers under oxidizing conditions.