Effect of doping of trivalent cations Ga³⁺, Sc³⁺, Y³⁺ in Li_1.3Al_0.3Ti_1.7 (PO₄)₃ (LATP) system on Li⁺ ion conductivity

We report the effect of trivalent cations dopants in the Li_1.3Al_0.3−xR_xTi_1.7(PO₄)₃ (R=Ga³⁺, Sc³⁺, Y³⁺) NASICON ceramic system in the concentration range x=0.01,0.03,0.05,0.07, on the Li⁺ ion conducting properties using impedance spectroscopy. The samples were prepared by solid state reaction method and characterized by X-Ray Diffraction and density measurements. The electrical properties were studied using impedance spectroscopy in frequency range 10 Hz to 20 MHz and temperature range 303 K to 423 K. Although the porosity of the material decreased with doping, the overall Li⁺ ion conductivity of the system did not improve with doping. Ionic radii of the dopant cations was found to be an important factor in formation of impurity phases and low Li⁺ ion conductivity. Gallium doped samples exhibited a higher Li⁺ ion conductivity compared to its scandium and yttrium doped counterparts.