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 coprecipitationroute leads to an orange (BaCe)-precursor powder (1). To improve the sinteringbehaviour, a small amount of Ge4+ was incorporated, leading to a (BaCe0.95/Ge0.05)-precursor(2). Both precursor powders results in fine-grained preceramic powders (1A, 2A) aftercalcination. The shrinkage and sintering behaviour of resulting powder compacts were studiedin comparison to a coarse-grained mixed-oxide BaCeO3 powder (3). Compacts of 2A reach arelative density of 90 % after sintering at 1350 °C with grain-sizes between 0.9−3.2 μm. Onthe other hand ceramics of 1A and 3 have, after sintering at 1500 °C (10 h), relative densitiesof 85 % and 76 %, respectively. Ceramic bodies of 1A consisted of phase-pure orthorhombicBaCeO3, whereas bodies of 2A show reflections of BaCeO3 and a Ba2GeO4 phase. DTAinvestigations 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 range880−910 °C