Structural properties of mixed conductor Ba1- xGd1- yLax+ yCo2O6- δ

Ragnar Strandbakke; David S Wragg; Magnus H Sørby; Matylda N Guzik; Anette E Gunnæs; Iga Szpunar; Sebastian Lech Wachowski; María Balaguer; Patricia A Carvalho; Aleksandra Mielewczyk-Gryń; Jose M Serra; Truls Norby

doi:10.1039/d2dt02277j

Structural properties of mixed conductor Ba_{1- x}Gd_{1- y}La_{x+ y}Co₂O_{6- δ}

Dalton Trans. 2022 Dec 13;51(48):18667-18677. doi: 10.1039/d2dt02277j.

Authors

Affiliations

¹ Department of Chemistry, University of Oslo, SMN, Gaustadalléen 21, NO-0349 Oslo, Norway. truls.norby@kjemi.uio.no.
² Department of Chemistry, University of Oslo, POB 1033 Blindern, NO-0315 Oslo, Norway.
³ Department for Hydrogen Technology, Institute for Energy Technology, NO-2027 Kjeller, Norway.
⁴ Department of Technology Systems, University of Oslo, POB 70, NO-2027 Kjeller, Norway.
⁵ Department of Physics, University of Oslo, POB 1048 Blindern, NO-0316 Oslo, Norway.
⁶ Faculty of Applied Physics and Mathematics, Advanced Materials Centre, Gdańsk University of Technology, Gdańsk, Poland.
⁷ Instituto de Tecnología Química, Universitat Politècnica de València, Consejo Superior de Investigaciones Científicas, Av. Naranjos s/n, E-46022, Valencia, Spain.
⁸ Materials Physics, SINTEF Industry, POB 124 Blindern, NO-0314 Oslo, Norway.

PMID: 36448547
DOI: 10.1039/d2dt02277j

Abstract

Ba_1-xGd_1-yLa_x+yCo₂O_6-δ (BGLC) compositions with large compositional ranges of Ba, Gd, and La have been characterised with respect to phase compositions, structure, and thermal and chemical expansion. The results show a system with large compositional flexibility, enabling tuning of functional properties and thermal and chemical expansion. We show anisotropic chemical expansion and detailed refinements of emerging phases as La is substituted for Ba and Gd. The dominating phase is the double perovskite structure Pmmm, which is A-site ordered along the c-axes and with O vacancy ordering along the b-axis in the Ln-layer. Phases emerging when substituting La for Ba are orthorhombic Ba-deficient Pbnm and cubic LaCoO₃-based R3̄c. When La is almost completely substituted for Gd, the material can be stabilised in Pmmm, or cubic Pm3̄m, depending on thermal and atmospheric history. We list thermal expansion coefficients for x = 0-0.3, y = 0.2.