In addition to being a satisfactory proton conducting ceramic material, Dysprosium doped Barium Zirconate Ba(Zr0.9Dy0.1)O3-δ has also shown oxide conducting properties. The fast oxygen transport at 600°C is mediated by the transition between Dy3+ and Dy4+, which is predicted to have a redox potential of 5.3 eV. Results will be presented on bulk sintered samples analyzed by Electron Paramagnetic Resonance (EPR) and impedance spectroscopy. From the EPR data, it appears a complete transformation between Dy4+ and Dy3+ is obtained by cooling in either Oxygen or Argon atmosphere, respectively. There has recently been reported supporting evidence using thermal gravimetric analysis (TGA) and high temperature X-Ray Diffraction (HT-XRD) studies. A critical factor for achieving high conductivity is directing the dopant to only B-site occupancy in this tolerance factor equals 1.0 cubic perovskite. Barium deficiency is monitored by XRD in synthesis of 50nm BZY-10 powders, pure and with up to 5% BaNiOx added. It is shown that Barium deficiency can be avoided at the temperature that balances the significantly exothermic enthalpy of formation. At slightly higher synthesis temperatures, the kinetically driven product with Yttrium co-occupation on the A-site and B-site is obtained. These results are completely independent of the presence of BaNiOx sintering aid. Future work will focus on preparation of Dysprosium doped Barium Zirconate nanoparticles. The duo proton/oxide conducting properties should lead to enhanced catalytic capabilities under a range of environmental conditions.

Redox properties of dysprosium 3+/4+ in barium zirconate

2019 Fall National Meeting

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