Preparation of Nd-doped BaCeO₃ proton-conducting ceramics by homogeneous oxalate coprecipitation

Abstract

Nd-doped BaCeO₃ have been obtained from homogeneous coprecipitated oxalates when calcined at temperatures T≥1000 °C. Ball-milling of the calcined powders well disperses the agglomerates and consequently has a beneficial effect in the densification process. The calcination temperature has a major influence on the sintering process and powders calcined at 1100 °C possess good sinterabilities. The pressure applied to press the green pellets has no apparent influence on the sintered density at sintering temperatures ofT≥1400 °C. By controlling the processing variables it was possible to obtain near fully dense Nd-doped BaCeO₃ ceramics with homogeneous microstructure at a sintering temperature as low as 1300 °C. Electrical conductivities of the sintered samples were measured in dry and moist air and in hydrogen in the temperature range 500–800 °C using complex impedance techniques. Much higher proton conductivity was obtained in this work compared with previously reported values, in which the samples were prepared from traditional ceramic methods.

References

1. H. Iwahara, H. Uchida, K. Ono and K. Ogaki, J. Electrochem. Soc., 1988, 135, 529.
2. H. Iwahara, H. Uchida and K. Morimoto, J. Electrochem. Soc., 1990, 137, 462.
3. N. Bonanos, B. Ellis and M. Mahmood, Solid State Ionics, 1991, 44, 305.
4. H. Iwahara, Chem. Sens. Technol., 1991, 3, 117.
5. S. Hamakawa, T. Hibino and H. Iwahara, J. Electrochem. Soc., 1993, 140, 459.
6. C. W. Tanner and A. V. Virkar, J. Electrochem. Soc., 1996, 143, 1386.
7. H. Iwahara, T. Esaka, H. Uchida and N. Maeda, Solid State Ionics, 1981, 3/4, 359.
8. N. Bonanos, B. Ellis, K. S. Knight and M. Mahmood, Solid State Ionics, 1989, 35, 179.
9. M. H. Zhen and X. Chen, Solid State Ionics, 1994, 70/71, 595.
10. E. M. Kelder, O. C. J. Nijs and J. Schoonman, Solid State Ionics, 1994, 68, 5.
11. V. Agarwal and M. L. Liu, J. Mater. Sci., 1997, 32, 619.
12. S. D. Flint and R. C. T. Slade, Solid State Ionics, 1995, 77, 305.
13. B. A. Boukamp, Solid State Ionics, 1986, 18/19, 136.
14. R. C. T. Slade and N. Singh, Solid State Ionics, 1991, 46, 111.
15. D. A. Stevenson, N. Jiang, R. M. Buchanan and F. E. G. Henn, Solid State Ionics, 1993, 62, 279.