Sintering of a fine-grained BaCeO3 powder obtained from a co-precipitation method

The formation of BaCeO₃ by a co-precipitation method is described herein. The co-precipitation route leads to an orange (BaCe)-precursor powder (1). To improve the sintering behaviour, a small amount of Ge⁴⁺ was incorporated, leading to a (BaCe_0.95/Ge_0.05)-precursor (2). Both precursor powders results in fine-grained preceramic powders (1A, 2A) after calcination. The shrinkage and sintering behaviour of resulting powder compacts were studied in comparison to a coarse-grained mixed-oxide BaCeO₃ powder (3). Compacts of 2A reach a relative density of 90% after sintering at 1350 °C with grain sizes between 0.9 and 3.2 μm. On the other hand ceramics of 1A and 3 have, after sintering at 1500 °C (10 h), relative densities of 85 and 76%, respectively. Ceramic bodies of 1A consisted of phase-pure orthorhombic BaCeO₃, whereas bodies of 2A show reflections of BaCeO₃ and a Ba₂GeO₄ phase. DTA investigations of samples 1A and 2A reveal three phase transitions at 255 °C (1A) and 256 °C (2A) as well as 383 °C (1A) and 380 °C (2A). A very weak one can be obtained in the range 880–910 °C.