In situ Neutron Diffraction Study of BaCe0.4Zr0.4Y0.2O3-δ (BCZY) Proton Conducting Perovskite

BASBUS J.F.; ARCE M.D.; ALONSO, J. A.; GONZALEZ M.; CUELLO, GABRIEL J.; FERNÁNDEZ-DÍAZ, MARÍA T.

2021-02-01/2021-02-28

Química

Energia-Varios

Ba(Ce,Zr)O3 based materials have potential application as electrolytes for proton conducting solid oxide fuel cells (PC-SOFCs) due to their lower operating temperatures and higher efficiencies with respect to commercial electrolytes. Also, these materials have been proposed as PC solid oxide electrolyzer cells (PC-SOECs) electrolytes, isotopic separation membranes and water sensors. In this sense, the understanding of protonic defect mobilities and lattice distortions are crucial to develop new materials with high protonic conduction. BaCe0.4Zr0.4Y0.2O3−δ (BCZY) perovskite is a well-known proton conductor and the protonic transport properties would depend on crystal structure and local distortions associated to temperatures and gas moist. Thus, BCZY perovskite was studied by Neutron Diffraction (ND) where the patterns were collected as a function of temperature under dry and wet air (~ 2 % D2O vapor). The phase transition from rhombohedral to cubic symmetry between 400 and 600 °C was determined and the crystallographic properties were evaluated. The D occupancy is full below 400 °C and the 2nd order phase transition occurs at ~ 520 °C when D occupancy starts to decrease. According to these results, the protonic transport mechanism depends on D occupancy and it is not related to the phase transition.