Preparation and characterization of sol–gel derived high lithium ion conductive NZP-type ceramics Li1 + x AlxTi2 − x(PO4)3

• A new and innovative sol–gel procedure is presented.
• Sintering is done by field assisted sintering reaching relative densities up to 98%.
• The complete synthesis leads to high purity LATP material avoiding AlPO4.
• A maximum conductivity of 10−3 S/cm at room temperature is achieved.

Solid electrolytes based on lithium titanium aluminum phosphate (LATP) with the composition Li1.3Al0.3Ti1.7(PO4)3 were prepared employing a modified sol–gel method. Amorphous LATP was converted to a ceramic by a heat treatment at 900 °C. Densification was achieved by field assisted sintering (FAST) in the temperature range of 850 to 1100 °C. The resulting phase composition, crystal structure and theoretical density were obtained from XRD analysis. Electrical properties of the samples, such as ionic conductivity, were calculated from impedance measurements in the frequency range from 20 Hz to 1 MHz. The ionic conductivities of the sintered pellets were calculated from impedance data and were correlated with the sample density. A maximum conductivity in the order of 10− 3 S cm− 1 at room temperature is obtained for phase-pure compositions combined with a high relative density of 98%.