Effect of fluorine, chlorine and bromine doping on the properties of gadolinium doped barium cerate electrolytes

Electrical properties of proton-conducting BaCe0.8Y0.2O3-δ and the effects of bromine addition

“…given that Ba is introduced stoichiometrically during the synthesis, it may be the case that the excess Ba which is not incorporated in the structure, leading to Ba vacancies in the bulk, is not completely evaporated and is, therefore, in higher concentrations in the grain boundaries, which has the effect of lowering stability in comparison to samples without Br addition. In contrast, other authors report that Br-doped barium cerate material enhances stability in comparison to the undoped phase [12]. Discrepancies between different studies may be related to uncontrolled, variable halogen content on hightemperature sintering.…”

“…An alternative but, until recently, little explored strategy is to dope the oxide sublattice with halogen anions in order to lower the basicity of the anion network, thereby offering the possibility of enhanced stability in acidic gases such as CO2 and high watervapour partial pressures [11][12][13]. Although Cl and Br atoms are less electronegative (more basic) than elemental O, it may be expected that the lower charge of the monovalent halogen anions imparts less basic character in the O 2anion network leading to improved stability of halogen-doped materials in acidic environments.…”

“…Wang et al [11] reported improved stability and higher proton conductivity in Cl-doped BaCe0.8Sm0.2O3-, whereas Su and co-workers demonstrated a power density improvement of 20 % in a single cell PCFC with a F-doped BaCe0.8Sm0.2O3-electrolyte compared to the halogen-free analogue with negligible degradation after 146 hours [14]. On employing F, Cl and Br as anion dopants in BaCe0.9Gd0.1O3-, Zhou et al reported that the halogens enter the lattice without structural changes while at the same time either lowering conductivity in air (F and Cl) or having a slightly positive effect on transport (Br) [12]. All these studies involve high-temperature annealing in the range 1375-1450 °C to sinter prepared powders into dense, gas-tight membranes.…”

Advanced materials for SOFC application: Strategies for the development of highly conductive and stable solid oxide proton electrolytes

“…It seems that the solid state synthesis is preferable for the achievement of anionic-substituted systems with expected compositions. For example, Zhou et al[104] …”

A Comparative Study of Conventional and Microwave Sintering of BaCe1 − xGdxO3 − δ Ceramic

“…This study is essentially expected to contribute towards the ongoing efforts to obtain dense ceramic products from nanometric particles for SOFCs based on the application of proton conductors. [14] 1400 °C/5 h Conventional solid-state reaction route [46,47] 1200 °C/6 h Conventional solid-state reaction route [48] 1200 °C/12 h Conventional solid-state reaction route [49] 1150 °C/2 h Conventional solid-state reaction route [50] 1350 °C/6 h Conventional solid-state reaction route [15] 1150 °С/2 h Conventional solid-state reaction route [51] 1350 °C/10 h conventional solid-state reaction route [52] 1350 •C/10 h Conventional solid state reaction route [53] 1400 °C/10 h Conventional solid state reaction route [54] 950 °C/2 h Polymeric precursors route This work…”