title: Instability of the Ionic Conductor Li6BaLa2B2O12(B = Nb, Ta): Barium Exsolution from the Garnet Network Leading to CO2Capture.
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.
authors.affiliation: Université Bretagne Loire, Université du Maine , Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Galven
authors.affiliation: Université Bretagne Loire, Université du Maine , Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Corbel
authors.affiliation: Université Bretagne Loire, Université du Maine , Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Le Berre
authors.affiliation: Université Bretagne Loire, Université du Maine , Institut des Molécules et Matériaux du Mans (IMMM), UMR CNRS 6283, avenue O. Messiaen, 72085 Le Mans, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Crosnier-Lopez