Effective acceptor concentration and exsolution of transition metal nanoparticles from proton-conducting oxide electrolytes based on Y-doped

Proton-conducting oxide electrolytes based on Y-doped BaZrO3 represent the state-of-the-art within electrochemical energy conversion devices. The electrolytes are nominally acceptor-doped with 20 mol% Y3+ and/or Yb3+ on the perovskite B-site and transition metal sintering additives such as NiO are utilized to obtain dense ceramic electrolytes. However, the effective acceptor concentration of the electrolytes is significantly suppressed, leading to reduced protonic conductivity and electrochemical performance. Synchrotron radiation X-ray powder diffraction (SR-XPD) at ESRF is well suited to assess the site occupancy of the Y/Yb-dopants (A-site vs B-site), as well the preferred position of Ni/Cu/Zn. The study aims to provide a complete structural description of the material and site occupancies that complies with the measured effective acceptor concentrations.