Oxygen permeation in bismuth-based materials. Part I: Sintering and oxygen permeation fluxes

Abstract

Oxygen permeation measurements were performed on two layered bismuth based oxide ceramics: a rhombohedral phase belonging to the Bi 2 O 3 -CaO system, (Bi 2 O 3 ) 0.73 -(CaO) 0.27 (BICAO) and a BICOVOX phase. Oxygen permeability for these systems was compared to permeability of the cubic fluorite type structure with composition (Bi 2 O 3 ) 0.75 (Er 2 O 3 ) 0.25 (BE25). Low oxygen permeability was observed for the pure ceramic.As for BE25, permeability was considerably increased if 40 vol% of silver was added to BICAO. In contrast, permeability was not improved by addition of gold to BICOVOX. For this latter phase, the oxygen molecular exchange at the surface is clearly the limiting step in the oxygen transfer.

Synthesis of fuel cell grade Bi2Co0.1V0.9O5.35 solid electrolyte thin films

“…Divalent metal substituted ␥-Bi 4 V 2 O 11 (BIMEVOX) is the family of solid electrolytes with high ionic conductivity in the temperature range 400-700 • C. These materials are proven to be potential materials for intermediate temperature solid oxide fuel cells (SOFCs), oxygen pump, and oxygen sensor applications [1,2]. The conductivity above 400 • C is two orders of magnitude higher than that of the oxide ion conductors like yttria-stabilized zirconia.…”

Oxygen Diffusion Mechanisms in Two Series of Oxide Ion Conductors: BIMEVOX and Brownmillerite Materials

“…Faradic yields close to 100% with current density up to 2A.cm -2 (1A/cm -2 is equivalent to 3.5cm 3 .min -1 ) were obtained with membranes simply made of a dense BIMEVOX ceramic, sandwiched between two gold grids, used as current collector 26,27 . In contrast, low oxygen permeation was observed when membranes were placed between two different atmospheres of oxygen 28,29 .…”

Crystal structure and phase transition in the doped super‐ionic conductor bismuth vanadate Bi4(V,Fe)2O11 revealed by neutron diffraction

“…A lot of efforts was undertaken to stabilize the γ‐phase at temperatures as low as possible, mainly through the doping of parent compounds with various cations. Different cation modifications were studied, particularly, the vanadium substituted compounds ${\rm Bi}_{4} ({\rm V}_{1- x} ,\kern 1pt {\rm Me}_{x} )_{2} \kern 1pt {\rm O}_{11- y} $ , (Me – substituting ion) 4, 12–45. However, despite of the numerous studies, the crystal structure of Bi 4 V 2 O 11− y and its polymorphs is still not completely understood due to complexity and variation with doping.…”