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High oxide ion conduction in the sintered oxides of the system Bi2O3-Gd2O3

Research paper by T. Takahashi, T. Esaka, H. Iwahara

Indexed on: 01 Aug '75Published on: 01 Aug '75Published in: Journal of Applied Electrochemistry



Abstract

In order to characterize the conduction behaviour in the sintered oxides of the system Bi2O2-Gd2O3, the electrical conductivity in air and the emf of the oxygen concentration cell were measured.The new rhombohedral phase found in this system exhibited high oxide ion conduction especially at relatively high oxygen pressure. The rhombohedral phase was stable in the composition range between 10 and 30 mol% Gd2O3 below 600° C and was transformed into the face-centred cubic phase with rising temperature, the conduction in which was by oxide ion as in the rhombohedral phase. At concentrations greater than 35 mol% Gd2O3, the fcc phase was stable over a wide range of temperature (∼900° C) and kept its high oxide ion conduction. The conductivities of rhombohedral (Bi2O3)0.90(Gd2O3)0.10 and fcc (Bi2O3)0.65(Gd2O3)0.35* are 4.5 and 2.4×10−2 cm−1 at 600°C, respectively. These are about one order of magnitude higher than that of the well-known yttria-stabilized zirconia at corresponding temperatures. High-oxide ion-conduction in the rhombohedral and fcc phase was considered to be due to the appreciable numbers of oxide ion vacancies in these crystals.