Inelastic neutron scattering studies of ?-Bi2O3 -related oxide-ion conductors
International Conference on Neutron Scattering
Inelastic neutron scattering is the only experimental technique that simultaneously probes ionic diffusion (as quasielastic neutron scattering, QENS) and lattice dynamics (as a generalised density of states, GDOS). In solid-state ionic conductors where the diffusing species has a predominantly incoherent neutron scattering cross section – i.e., H – key parameters describing diffusion can be extracted directly by modelling the form of the QENS. QENS analysis is a far more complex (and unresolved) problem when the diffusing atoms have significant coherent cross-sections, such as O and Li. However, it is possible to interpret QENS indirectly in such cases by using the experimental GDOS to validate ab initio dynamics simulations, then interrogating the simulations to identify diffusion mechanisms. This is obviously most effective when the experimental signal is strong, i.e., conductivity is high. In the case of oxide-ionic conductors, this points to stabilised versionsof ?-Bi2O3. Here, we present new results for a series of cubic ?-Bi2O3-related compounds with (3+3)-D incommensurately modulated structures. We identify a mechanism by which oxide ions migrate through continuous and nearly isotropic channels. The results are compared to conductivity data and theoretical models for pure ?-Bi2O3, and used to suggest chemical modifications that could maximise performance and cycling stability.
Neutron diffraction, Inelastic scattering, Ionic conductivity, Diffusion, Oxides, Simulation
Ling, C., Wind, J., & Mole, R. (2017). Inelastic neutron scattering studies of ?-Bi2O3 -related oxide-ion conductors. Paper presented at ICNS 2017 (International Conference on Neutron Scattering), Daejeon, South Korea, 9 to 13 July 2017. Retrieved from: http://www.icns2017.org/program.php