Revealing the Crystal Structure of BaCe0.4Zr0.4Y 0.2O3 δ Proton Conducting Perovskite and i ts Correlation with Transport Properties

NAPOLITANO, FEDERICO R.; JIMENEZ, CATALINA E.; ARCE, MAURICIO D.; CUELLO, GABRIEL J.; MOGNI, LILIANA V.; BASBUS, JUAN F.; BONANOS, NIKOLAOS; SERQUIS, ADRIANA

Buenos Aires

Congreso; II Congreso de Técnicas Neutrónicas; 2019

LAHN-CNEA

BaCe0.4 Zr0.4 Y0.2O3-δ (BCZY) perovskite is an excellent candidate as electrolyte for Proton Conducting Solid Oxide Fuel Cell (PC-SOFC) due to its high bulk protonic conductivity and good CO2 tolerance, nevertheless, theoperating temperature range needs to be carefully determined for its application. The protonic transport properties depend on crystal structure and local distortions around cations, according to temperature andatmosphere. Crystallographic and electrochemical properties were simultaneously studied by in-operando synchrotron X-Ray Diffraction (XRD) and Electrochemical Impedance Spectroscopy (EIS), respectively. A strong correlation between lattice parameter and conductivity was observed, especially between 400 and 700 °C where both curves show the same tendencies. The protonic conductivity range was analyzed by H/D isotopic effect on impedance spectra, being the dominant transport mechanism below 600 °C, while oxygen vacancies dominate above 600 °C. BCZY presents rhombohedral symmetry below 400 °C, and a transition to cubicsymmetry at 600 ºC, resulting from the simultaneous refinement of laboratory XRD and Neutron Diffraction (ND) patterns. Additionally, O-O distances in octahedra are ~ 3.1 Å, which are comparable with jump lengthscalculated by Quasielastic Neutron Scattering (QENS) data. These results support the protonic self-diffusion as transport mechanism by H+ hopping between intraoctahedral O sites.