Competing ferri- and antiferromagnetic phases in geometrically frustrated LuFe2O4.

We present a detailed study of magnetism in LuFe(2)O(4), combining magnetization measurements with neutron and soft x-ray diffraction. The magnetic phase diagram in the vicinity of T(N) involves a metamagnetic transition separating an antiferro- and a ferrimagnetic phase. For both phases the spin structure is refined by neutron diffraction.

Dynamic solubility limits in nanosized olivine LiFePO4.

Because of its stability, nanosized olivine LiFePO(4) opens the door toward high-power Li-ion battery technology for large-scale applications as required for plug-in hybrid vehicles. Here, we reveal that the thermodynamics of first-order phase transitions in nanoinsertion materials is distinctly different from bulk materials as demonstrated by the decreasing miscibility gap that appears to be strongly dependent on the overall composition in LiFePO(4). In contrast to our common thermodynamic knowledge, that dictates solubility limits to be independent of the overall composition, combined neutron and X-ray diffraction reveals strongly varying solubility limits below particle sizes of 35 nm.

Size effects in the Li(4+x)Ti(5)O(12) spinel.

The nanosized Li(4+x)Ti(5)O(12) spinel is investigated by electrochemical (dis)charging and neutron diffraction. The near-surface environment of the nanosized particles allows higher Li ion occupancies, leading to a larger storage capacity. However, too high surface lithium storage leads to irreversible capacity loss, most likely due to surface reconstruction or mechanical failure.

The electronic structure and ionic diffusion of nanoscale LiTiO2 anatase.

Upon lithium insertion in the pristine TiO2 anatase phase the theoretical maximum of LiTiO2 can be reached in crystallite sizes less than approximately 10 nm, whereas bulk compositions appear limited to Li(x) approximately 0.6TiO2 at room temperature. Both X-ray absorption spectroscopy (XAS) and ab initio calculations have been applied to probe the electronic structure of the newly formed LiTiO2 phase.

Direct observation of space charge induced hydrogen ion insertion in nanoscale anatase TiO2.

Space charge induced 2H+ densities up to 2H+ (0.17)TiO2 are observed directly using neutron diffraction on two different nanoscale particle sizes of anatase TiO2 immersed in sulfuric acid, and consistent with experimental evidence modelling shows that these ions show rapid self diffusion.