Synthesis and characterization of nanosized lithium manganate and its derivatives

Spinel lithium manganese oxide, LiMn2O4 and its derivatives are prepared by the sol–gel method. The lattice constant of the pure material is calculated as 8.23 Å. Different transition metal cations of chromium, iron, cobalt, nickel, copper and zinc (0.05 and 0.15 M) are doped in place of manganese in the LiMn2O4. X-ray powder diffraction data show that the spinel framework preserved its integrity upon doping. Formation of a single phase and the purity of the samples are confirmed by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The crystallite size of the samples is calculated by use of the Scherrer formula and is found to be within a range of 43–66 nm. The electrical conductivity of the samples is determined over a temperature range of 200–300 K by means of four-point probe method. An increasing trend of conductivity with increase in temperature is noted for all the samples. The parent compound LiMn2O4 has a conductivity value of 3.47 × 10−4 ohm−1 cm−1 at room temperature. This value increases on doping with the above-mentioned transition metal cations.