Investigation on double perovskite Ba₄Ca₂Ta₂O₁₁

Sébastien Baliteau (1) , Fabrice Mauvy (1) , Sébastien Fourcade (1) , Jean-Claude Grenier (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

The structure, conductivity and water uptake of the oxygen-deficient perovskite-type compound Ba₄Ca₂Ta₂O₁₁ have been investigated. Ba₄Ca₂Ta₂O₁₁ crystallizes in the cryolite structure (cubic, Fm3m SG) with a = 8.4508(2) Å, under dry air. The compound can be partially hydrated up to a maximum water content of approximately 0.52 mol H₂O per mol Ba₄Ca₂Ta₂O₁₁. In moist air, the structure symmetry becomes monoclinic (C2/m) and the temperature dependence of total conductivity shows a different behavior because of changes in transport mechanism. Three regions can be observed as a function of temperature. For the low temperature range 200–400 °C, the protonic conduction is prevailing with an activation energy E_A = 0.85 eV. In the intermediate temperature range (400–600 °C), O²⁻ anionic and protonic conductions are mixed with an activation energy E_A = 0.45 eV and in the third region, for temperatures above 600 °C, O²⁻conduction is prevailing with an activation energy E_A = 0.85 eV.

Mots clés: Ba₄Ca₂Ta₂O₁₁; Double perovskite; Oxygen ionic and protonic conductions

Domaines: Matériaux

Sébastien Baliteau, Fabrice Mauvy, Sébastien Fourcade, Jean-Claude Grenier. Investigation on double perovskite Ba₄Ca₂Ta₂O₁₁. Solid State Sciences, 2009, 11 (9), pp.1572-1575. ⟨10.1016/j.solidstatesciences.2009.06.023⟩. ⟨hal-00432660⟩