Raman and FTIR spectroscopy study of LiFeTiO4 and Li2FeTiO4

We report the Fourier transform infrared (FTIR)-Raman spectroscopy study of spinel Li-Fe-Ti-O oxides viz., LiFeTiO4 and Li2FeTiO4 in order to probe structural details such as type of bonding networks viz., octahedral and tetrahedral, and type of different atomic bonds present in those materials. Both the samples were prepared through solid-state reaction route prior to high-energy ball-milling. All the phases prepared through solid-state reaction and ball-milled were probed using X-ray diffraction, field emission scanning electron microscopy, and FTIR-Raman spectroscopy. X-ray diffraction study indicates spinel phase formation with Fd3m space group symmetry for both LiFeTiO4 and Li2FeTiO4. However, pure phase of Li2FeTiO4 was not achieved in these preparation routes, rather mixed phases of Li2FeTiO4 and Fe2TiO4 were achieved. Field emission scanning electron microscopy (FESEM) analysis indicated porous microstructure for LiFeTiO4 while more agglomerated microstructure for Li2FeTiO4. Ball-milling reduces the grain size partly for both the samples. FTIR-Raman spectroscopy indicates the presence of LiO4 tetrahedral, LiO6 and TiO6 octahedral in the spinel network. Presence of Li-Li-O type bonding was also indicated from spectroscopy analysis. Existence of Fe2TiO4 phase with Li2FeTiO4 was also identified from both FTIR and Raman spectrum. Effect of ball-milling on the spectrum has been exhibited by broadening and peak shifting the FTIR-Raman spectrum, arising from the enhanced lattice strain and structural disorder.