Proton diffusivity in the BaZr0.9Y0.1O3-{\delta} proton conductor

TL;DR

This study investigates proton diffusion in BaZr0.9Y0.1O3-{ extdelta} using impedance spectroscopy and neutron scattering, revealing temperature-dependent activation energies and different diffusion mechanisms.

Contribution

It provides a comparative analysis of bulk and grain boundary proton diffusivities and highlights the temperature-dependent crossover in diffusion processes.

Findings

Bulk diffusivity follows Arrhenius law with 0.46 eV activation energy.

Grain boundary diffusivity has higher activation energy of 1.21 eV.

Different diffusion mechanisms are suggested above and below 700 K.

Abstract

The thermally activated proton diffusion in BaZr0.9Y0.1O3-{\delta} was studied with electrochemical impedance spectroscopy (IS) and quasi-elastic neutron scattering (QENS) in the temperature range from 300 K to 900 K. The diffusivities for the bulk material and the grain boundaries as obtained by IS obey an Arrhenius law with activation energies of 0.46 eV and 1.21 eV, respectively. The activation energies obtained by IS for the bulk are 0.26 eV above 700 K and 0.46 eV, below 700 K. The total diffusivity as obtained by IS is by one order of magnitude lower than the microscopic diffusivity as obtained by QENS. The activation energies obtained by QENS are 0.13 eV above 700 K and 0.04 eV, below 700 K. At about 700 K, the diffusion constants for IS and QENS have a remarkable crossover, suggesting two processes with different activation energies.