Using quasielastic neutron scattering (QENS), we have investigated a self-diffusive behavior of Li+ ions for both Li7Mn2O 4 and Li71.1Mn1.9O4 spinels. In addition, we have carried out elastic and inelastic neutron scattering measurements using the same samples, to study the interrelationship between Li+ self-diffusion, magnetism, and charge distribution in the lattice. From the QENS results, the self-diffusion of Li+ was observable above 280 K, and a self-diffusion coefficient (DsLi) for Li7Mn 2O4 was estimated as ~10-8 cm2/s at 400 K. DsLi for Li71.1Mn1.9O4 was comparable to that for Li7Mn2O4. Furthermore, combining with the results of elastic and inelastic measurements, it was found that Li71.1Mn 1.9O4 undergoes a transition from a low-temperature (T) short-range charge-ordered (SRCO) phase to a high-T charge-disordered (CDO) phase at 280 K. The structure of the SRCO was determined as a hexagon, because the formation of hexagon spin clusters was deduced from a magnetic diffuse scattering at low T. Assuming the presence of the SRCO-CDO transition at 280 K, both the anomaly of the diffusive behavior at 280 K and the local lattice distortion below 280 K are reasonably explained, despite the absence of long-range CO for Li71.1Mn1.9O4.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Mar 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics