Instability of the Ionic Conductor Li6BaLa2B2O12 (B = Nb, Ta): Barium Exsolution from the Garnet Network Leading to CO2 Capture

Cyrille Galven; Gwenaël Corbel; Françoise Le Berre; Marie-Pierre Crosnier-Lopez

doi:10.1021/acs.inorgchem.6b02238

Instability of the Ionic Conductor Li₆BaLa₂B₂O₁₂ (B = Nb, Ta): Barium Exsolution from the Garnet Network Leading to CO₂ Capture

Inorg Chem. 2016 Dec 19;55(24):12872-12880. doi: 10.1021/acs.inorgchem.6b02238. Epub 2016 Nov 23.

Authors

Cyrille Galven¹, Gwenaël Corbel¹, Françoise Le Berre¹, Marie-Pierre Crosnier-Lopez¹

Affiliation

¹ Université Bretagne Loire, Université du Maine , Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, avenue O. Messiaen, 72085 Le Mans, France.

PMID: 27989195
DOI: 10.1021/acs.inorgchem.6b02238

Abstract

The instability of the two garnets Li₆BaLa₂B₂O₁₂ (B = Nb, Ta) has been studied on samples prepared in powder form by solid-state reaction. For this study, we coupled different techniques: powder X-ray diffraction, IR spectrometry, thermal analysis, transmission electron microscopy, and complex impedance spectroscopy. We showed that in ambient air and at low temperature (<150 °C), a spontaneous Li⁺/H⁺ exchange occurs. At higher temperature (500-700 °C), a progressive exsolution of the barium from the garnet framework is observed, leading to the formation of a second garnet, BaCO₃, and a 3D cubic perovskite. To conclude this work, we studied the impact of barium exsolution on the ionic conductivity measured by complex impedance spectroscopy. We observed a significant decrease in the starting bulk conductivity (60%) when the pellet is heated at 500 °C for 5 h.