Dopant Concentration and Short-Range Structure Dependence of Diffusional Proton Dynamics in Hydrated BaInxZr1-xO3-x/2 (x=0.10 and 0.50)

Journal article, 2010

We investigate proton self-dynamics in the acceptor-doped and hydrated proton-conducting perovskite-type oxides BaInxZr1-xO3-x/2 (x = 0.10 and 0.50) on a microscopic length scale for temperatures in the range 470-525 K, using neutron spin-echo spectroscopy. For the highly doped material (x = 0.50), we observe a wide range of translational diffusional rates of the protons in the Structure, oil the nanosecond time scale and with in effective activation energy of about 0.75 eV. The wide distribution of diffusional rates is related to the In-doping, which creates local structural distortions or the average Cubic Structure and thus many structurally different Configurations of the protons, each with slightly different energy barriers for the protonic motion. For the weakly doped material (x = 0.10), which has a more ordered local Structure, the results show proton dynamics oil a Much more well-defined time scale, similar to 60 ps at 500 K, but also Suggest that a significant part of the protons ill the Structure are "immobile" within the experimental neutron spin-echo time window (similar to 5 ps to 1.3 ns). Furthermore, the results indicate that the dopant atoms affect the proton diffusion ill a nonlocalized manner and not as well-localized trapping centers.