Compounds which exhibit high hydrogen conduction are currently of considerable interest due to potential applications in devices such as fuel cells and hydrogen sensors. Protonic conduction in perovskite-type oxides (e.g. SrCe0.95Yb0.05O3-d) has been extensively examined, while similar information on hydride conduction in oxides is lacking. Quasi-elastic neutron scattering (QENS) has provided quantitative information on hydride diffusion in the novel transition metal oxide hydride LaSrCoO3H0.7. Variable temperature, high resolution QENS data reveal the onset of hydride anion mobility above 675K via a jump process involving long-range diffusion of individual hydride anions. The site-to-site hopping distance is equal to the length of the a axis of the crystal unit cell, suggesting that diffusion occurs between vacancies in the hydride anion sublattice. Furthermore, diffusion coefficients have been used to obtain an estimate of the conductivity, which is significantly higher than has been observed in proton conducting materials.
CA Bridges (University of Liverpool), F Fernández-Alonso (ISIS), JP Goff, MJ Rosseinsky (University of Liverpool)
Research date: December 2006
Prof MJ Rosseinsky, [firstname.lastname@example.org] CA Bridges et al., J. Am. Chem. Soc. 92 (2005) 5996