Studies on rheological, structural, optical, electrical and surface properties of LiMn₂O₄ thin films by varied spin rates

LiMn₂O₄ thin films prepared by cost-effective spin coating method using optimized coating conditions are reported. Spin rate was varied and spin rate dependent properties were studied. Prepared films were characterized for their structural, morphological and optical properties. X-ray diffraction study of LiMn₂O₄ thin films confirmed the cubic spinel structure with the preferred orientation along (1 1 1) plane. Optical absorption studies showed band gap energy of 3.02 eV for the grown LiMn₂O₄ films. FT-IR bands assigned to asymmetric stretching modes of MnO₆ group were located around 623 cm^-1 and 514 cm^-1 for the LiMn₂O₄ thin films. The weak band observed at 437 cm^-1 was attributed to the LiO₄ tetrahedra. The films showed high conductivity value 0.79 S/cm indicating the generation of effective network of the film for enhanced charge transport. AFM micrographs of the LiMn₂O₄ films deposited at 3000 rpm and 3500 rpm showed uniform distribution of fine grains throughout the surface without any dark pits, pinholes and cracks.