Evidence of band structure modification due to Jahn-Teller distortion in LixMn2O4 by photoacoustic spectroscopy

Photoacoustic (PA) spectra of Li0.9Mn2O4, LiMn2O4 and Li1.1Mn2O4 at two temperatures, 298 K and 280 K which are, respectively, above and below the Jahn-Teller phase transition temperature, 290 K, are determined. The spectra of LiMn2O4 and Li1.1Mn2O4 below the transition temperature are found to be significantly different from their respective spectra above the transition temperature. However, the PA spectra of Li0.9Mn2O4 at both these temperatures show only a minor difference between each other compared with the changes occurring in LiMn2O4 and Li1.1Mn2O4. These effects are explained on the basis of the predominant JT tetragonal distortion in cubic LixMn2O4 with a high Li content, which brings forth a modification in their electronic structure