Ceramics-Silikáty 54 (1) 38-46 (2010)

SYNTHESIS AND CHARACTERIZATION OF Li[Mn_2-x Mg_x]O₄ (x = 0.0-0.3) PREPARED BY SOL-GEL SYNTHESIS

P. Singh, A. Sil, M. Nath, S. Ray

XRD analysis of Li[Mn_2-x Mg_x]O₄ (x = 0.0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3) powders synthesized by a sol-gel process, shows single phase cubic spinel structure having space group Fd3m up to x = 0.25. When Mg content increases to x = 0.3, second phase with space group P4₃32 appears. TG (Thermo Gravimetric) analysis shows the oxygen loss from the structure begins at lower temperature as the Mg content increases. DTA (Differential Thermogravimetric Analysis) shows stabilization of orthorhombic LiMnO₂ and tetragonal Mn₃O₄ by Mg doping. Number of vibrational bands increase as the Mg content increases which indicate that the ordering of spinel structure increases and the reduction of the space group from O_h⁷ (Fd3m) to O⁷ (P4₃32). The discharge capacity of 122 mAh g^-1 has been observed for LiMn₂O₄ and it decreases when the increase in Mg content. In Mg doped samples Li[Mn_2-xMg_x]O₄, step corresponding to cubic-cubic transition decreases and gets completely removed for x = 0.25.

Keywords: Ceramic oxide; Sol-gel technique; X-ray diffraction; Thermogravimetric analysis