Abstract: Sodium fast ion conductors Na_3.3Zr_1.65-x·Ti_xSi_1.9P_1.1O_11.5 were prepared from mixtures of Na₃PO₄,ZrP₂O₇-ZrO₂-TiO₂-SiO₂ in platinum vessel at temperatures of 1173.2~1473.2Kfor several hours to 20 hand 40 h. Most of reactions were carried out at the temperature range 1373.2-1423.2 K. The phases, of NASICONplus ZrO₂ were found, in the composition range x = 0~0.4. Apure NASlCONphase was found with x = 0.5~0.9. Agalss state appeared in x>0.9. Theoretical densities were evaluated according to the cell parameters determined. Electrical conductivities were measured from room temperature to 673.2K. In the same phase range, the conductivity always decreases with increasing x. The best conductor is Na_3.3Zr_1.05Ti_0.6Si_1.9P_1.1O_11.5 with conductivity . 47.2(S·m^-1) ,at 673.2 K. The activation energy data show that most compositions of Na_3.3Zr_1.65-x·Ti_xSi_1.9P_1.1O_11.5 system are good conductors.

Key words: NASICON type compounds, Sodium fast ion conductors