Synthesis and Ionic Conductivity of Complex Phosphates Li1 +xTi1.8 –xFexGe0.2(PO4)3 with NASICON Structure

Phosphates Li 1 + x Ti 1.8 – x Fe x Ge 0.2 (PO 4 ) 3 ( x = 0.1–0.3) with the NASICON structure have been prepared and studied for the first time. It has been shown that co-doping with germanium and iron leads to significant increase in the ionic conductivity of the prepared materials at low degrees of titanium substitution. The influence of the synthesis method (solid-state and sol-gel) and conditions of precursor processing on the ionic conductivity of the materials has been studied. Optimum conditions for the mechanical processing of precursors have been found to obtain ceramics with the highest conductivity. Li 1.2 Ti 1.6 Fe 0.2 Ge 0.2 (PO 4 ) 3 prepared by the solid-state method exhibits the highest ionic conductivity at room temperature (1.7 × 10 –4 S/cm) among all samples.