Evidence of Jahn-Teller distortion in LixMn2O4 by thermal diffusivity measurements

Thermal diffusivities of LixMn2O4 (x=0.9, 1.0 and 1.1) polycrystalline pellets are determined by photoacoustic technique in the reflection configuration, at two temperatures, 298 K and 280 K, above and below their Jahn-Teller phase transition temperature (290 K). The diffusivities of LixMn2O4 at 280 K show a drastic reduction from their corresponding room temperature values (298 K) and the percentage of reduction in the thermal diffusivity for LixMn2O4 increases with their Li content. These effects are associated with the reduction in crystal symmetry due to structural deformation by Jahn-Teller distortion observed in LixMn2O4 below its transition temperature.