Observation of Li-atomic array in spinel-LiMn2O4 films spin-coated on Si substrates using an atomic force microscopy

The thin films of spinel-LiMn2O4 were synthesized on (100) Si substrates by a sol-gel method and subsequent furnace annealing at various temperatures (300-800 degrees C) for 30 min. Li and Mn acetates (the atomic ratio Li/Mn of 1:2) were used as a coating solution, and dissolved in methanol with a small amount of a chelating agent. The films were confirmed to be a single phase of LiMn2O4 (space group: Fd3m) by x-ray diffraction studies. The surface morphologies of the films were examined by an atomic force microscopy, showing that the films consisted of bar-shaped crystalline parts. The area of these parts extended with increasing the annealing temperature. In the films annealed at 300 degrees C, the Li atomic array with slight distortions was observed in an atomically flat surface, which was associated with an unit cell with a lattice spacing of 8.195 +/- 0.005 Angstrom on the (100) surface in spinel-LiMn2O4. (C) 2000 American Institute of Physics. [S0003-6951(00)03416-1].