Yttrium and hydrogen superstructure and correlation of lattice expansion and proton conductivity in the BaZr0.9 Y0.1 O 2.95 proton conductor

Abstract

Bragg reflections in Y-resonant x-ray diffractograms of BaZr0.9 Y0.1 O2.95 (BZY10) reveal that Y is organized in a superstructure. Comparison with neutron diffraction superstructure reflections in protonated/deuterated BZY10 suggests that both superstructures are linked, and that protons move in the landscape imposed by the Y. The thermal lattice expansion decreases abruptly for protonated BZY10 at T648±20 K, coinciding with the onset of lateral proton diffusion and suggesting a correlation of structural changes and proton conductivity. The chemical shift in the Y L1 -shell x-ray absorption spectra reveals a reduction from Y3+ toward Y2+ upon protonation. © 2009 American Institute of Physics.