6533b7d6fe1ef96bd1265d15

RESEARCH PRODUCT

Local environment of Barium, Cerium and Yttrium in BaCe1−xYxO3−δ ceramic protonic conductors

subject

description

Abstract Y-doped barium cerate protonic conductors with composition BaCe 1 −  x Y x O 3 −  δ ( x  = 0.02, 0.1, 0.2, 0.3) have been synthesized by sol–gel route, giving by X-ray diffraction tests a homogeneous crystalline phase. A commercial sample BaCe 0.8 Y 0.2 O 3 −  δ produced by combustion spray pyrolysis was also provided for comparison aim. The local structure around the cations was studied by X-ray absorption spectroscopy at the K-edges of Ba, Ce and Y. It is demonstrated that the insertion of yttrium in the site of cerium produces a remarkable local distortion of the dopant first-shell octahedral environment that affects also the next coordination shells by a static disorder increasing with dopant amount. For a dopant concentration estimated as x > 0.17, a poorly crystallized yttrium oxide phase that cannot be detected by X-ray diffraction is segregated. The static disorder around Y noticeably increases in the protonated samples and can be related to a preferential location of protons near the dopant.