Synthesis, structure and electrical conductivity of a new perovskite type barium cobaltate BaCoO_1.80(OH)_0.86

Abstract

Perovskite oxides exhibiting mixed protonic and electronic conductivities have interesting applications in protonic ceramic fuel cells. In this work, we report on a hydrated phase of BaCoO1.80(OH)0.86 synthesized using nebulized spray pyrolysis. Structural analysis based on X-ray and neutron powder diffraction data showed that the compound is isotypic to BaFeO2.33(OH)0.33. The water loss behaviour was studied using simultaneous thermal analysis and high temperature X-ray diffraction, indicating that protons (respectively water) can be stabilized within the compound up to temperatures significantly above 673 K, confirmed by ex situ Fourier transform infrared spectroscopy studies. Impedance spectroscopy was used to determine the conductivity characteristics of BaCoO1.80(OH)0.86, finding and a total electrical conductivity in the order of 10-4 S cm-1 at ambient temperature with an activation energy of 0.28 eV.

Revisiting the Crystal Structure of BaCe0.4Zr0.4Y0.2O3−δ Proton Conducting Perovskite and Its Correlation with Transport Properties

“…This behavior was also observed for other Ba-rich perovskites. For example, Knöchel et al and Waidha et al combined XRD and ND to evaluate the crystal structure of Ba­(Fe,Co)­O 3−δ mixed proton and electronic conductors with low and high water content. , Therefore, the real structure of BCZY can be determined by combining XRD and ND. Figure compares XRD and ND patterns of powders presaturated with H 2 O vapor at room temperature and the corresponding samples measured in air.…”

BaCoO2+δ: a new highly oxygen deficient perovskite-related phase with unusual Co coordination obtained by high temperature reaction with short reaction times

“…For this compound, square planar, but also 6-fold coordination of Fe 2+ and coordination numbers lower than four would have to result from the structural model suggested, originating from an only partial ordering of the anion vacancies, confirmed by Mössbauer spectroscopy. A structural similarity between the phase prepared here to this Fe-based phase is chemically plausible regarding the overall anion content and because barium ferrates / cobaltates are known for their structural similarity 11,13 . However, no tetrahedral coordination is possible from the ideal site symmetries of the Co sites (2x 4/mmm, 1x mmm).…”

“…results either in the formation of the trigonal BaCoO 2 modification, or cubic BaCoO 2.22 , or melting of the sample. The composition of the sample was determined from a combination of iodometric titration and energy dispersive X-ray spectroscopy (EDAX, Figure S1 in ESI) 9,11 . The average oxidation state of Co was determined to be Co +2.03 (2) with a 1:1 ratio of Ba:Co.…”

Compositional Dependence of Li-Ion Conductivity in Garnet-Rich Composite Electrolytes for All-Solid-State Lithium-Ion Batteries—Toward Understanding the Drawbacks of Ceramic-Rich Composites

“…The solvent-free membrane preparation has been chosen as garnets are known to undergo Li + /H + exchange, which can affect its intrinsic Li-ion conductivity . The ceramic garnet particles are synthesized via nebulized spray pyrolysis (NSP), which has been reported to provide particles with high surface area compared to solid-state synthesis routes due to significant lowering of annealing temperatures and times, − with particle sizes in the range of ∼1 μm and below. Although nanoparticles have been the choice of the filler and are known to increase the conductivity of the polymer-rich composites, the garnet particles chosen in this study aim to be a compromise for providing sufficient surface area for ceramic–polymer interactions while maintaining longer conductive pathways within the ceramic particles (which have a higher grain conductivity than the polymer) due to their larger sizes.…”