Influence of microstructure on the electrical properties of NASICON materials

NASICON-type compounds with the nominal formula, Na3Si2Zr1.88Y0.12PO12, were prepared by a typical ceramic route with different microstructures. The samples were fired in the temperature range 1190–1235°C with sintering periods between 2 and 80 h. Results showed a significant influence of the processing conditions on the microstructure, affecting both grain and grain boundaries. Electrical conductivity was mainly controlled by the grain boundary contribution, which is strongly dependent on the grain size and density of grain boundaries. A maximum conductivity value of about 2.7×10−3 S cm−1 at room temperature was obtained with samples sintered at 1220°C for 40 h.