G. Hirankumar

Influence of metals on the structural, vibrational, and electrical properties of lithium nickel phosphate

LiNi1 − xMxPO4 (M = Zn, Al and x = 0, 0.05, 0.10, 0.15, and 0.20) was synthesized by classical solid-state reaction method. The reaction temperature is determined by thermogravimetric analysis. X-ray diffraction patterns show that an impurity peak is absorbed for Al3+-doped samples but not in the case of Zn2+-doped samples. Laser Raman studies confirm that phase pure LiNiPO4 is formed and the dopant is entered into the host lattice. Impedance spectroscopy is used to study the ion dynamics of both doped and undoped systems. Higher DC conductivity value is observed for LiNi0.85Zn0.15PO4 and LiNi0.925Al0.05PO4 compared with pristine LiNiPO4. The temperature-dependent DC conductivity and the frequency-dependent dielectric loss maxima are found to obey the Arrhenius law of conduction. In the modulus analysis, the stretching exponent β is found to be temperature independent. The scaling behavior of the imaginary part of the electric modulus suggests that the relaxation mechanism is independent of temperatures. Electrochemical impedance spectroscopy (EIS) studies also show that electrical conductivity is increased upon Zn2+ and Al3+ doping.

Structural, Morphological, Vibrational and Electrical Studies on Zn Doped Nanocrystalline LiNiPO4

Olivine structured LiNi1-xZnxPO4 (x=0, 0.05, 0.10, 0.15, 0.20) have been prepared by a polyol method using 1, 2 propanediol as a polyol medium. The XRD results of pure and Zn doped LiNiPO4 sample authenticate the orthorhombic crystal structure with high crystalline nature. The crystallite size is calculated from the Debye Scherer formula and it is found in the range of 55-65nm and 49-55nm for undoped and doped samples respectively. The thermal properties of LiNi1-xZnxPO4 were investigated by thermo gravimetric analysis (TG) and differential thermal analysis. Laser Raman studies confirm that the dopant is entered in to the LiNiPO4 lattice. Morphology of the samples is analyzed through SEM analysis. The higher electrical conductivity is calculated for LiNi0.85Zn0.15PO4 sample compared with other concentrations of dopant and it is found to be 1.08×10-7 S cm-1 at ambient temperature. Dielectric and Modulus studies are also discussed through impedance spectroscopy.