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

Abstract

The formation of BaCeO 3 by a co-precipitation method is described herein. The coprecipitation route leads to an orange (BaCe)-precursor powder (1). To improve the sintering behaviour, a small amount of Ge 4+ 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 BaCeO 3 powder (3). Compacts of 2A reach a relative density of 90 % after sintering at 1350 °C with grain-sizes between 0.9−3.2 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 BaCeO 3 , whereas bodies of 2A show reflections of BaCeO 3 and a Ba 2 GeO 4 phase. DTA investigations of samples 1A and 2A reveal three phase transitions at 255 °C (1A) and 256 °C 2 (2A) as well as 383 °C (1A) and 380 °C (2A). A very weak one can be obtained in the range 880−910 °C.

Novel composite solid state electrolytes on the base of BaCeO3 and CeO2 for intermediate temperature electrochemical devices

“…The nature of the shrinkage of the sample BCS-3 is somewhat different. A significant change in the linear dimensions for this material begins at 1000 C, with the first expansion occurring in the temperature range of 1000e1100 C, and then shrinking from 1100 to 1500 C, which is consistent with the results of Chien et al [52] and Koferstein et al [65]. The maximum change in the linear dimensions of BCS-3 sample is 9%; probably, the temperature of 1500 C is insufficient to complete the process of sintering of the specific material.…”

Synthesis and characterization of a nano-scaled barium cerate perovskite powder using starch as polymerization agent

“…Even after sintering at 1500 °C for 10 h we do not obtain any dense ceramic bodies but the relative densities remained below 77 % [25]. In contrast, compacts made from the nano-sized powder 1 exhibit an improved sintering behaviour.…”

“…For comparative purposes, a coarse-grained BaCeO 3 powder (2) was prepared via a conventional mixed-oxide method and the resulting compacts had a green density of about 3.5 g/cm 3 as described and investigated elsewhere [25].…”

“…For comparison purposes we also investigated a coarse-grained BaCeO 3 powder (2) as described elsewhere [25]. That powder results from a conventional mixed-oxide process at 1150 °C for 4 h and has a specific surface area of 2.1 m 2 /g and thus an equivalent particle size of 449 nm.…”

“…Compacts on the basis of BaCeO 3 generally reveal only a moderate densification behaviour [4,25]. For application such as capacitors or in SOFCs the density of the ceramics must be high [26,27,28,29,30,31].…”