Synthesis and Na(+) Ion Conductivity of Stoichiometric Na(3)Zr(2)Si(2)PO(12) by Liquid-Phase Sintering with NaPO(3) Glass

Sodium super ionic conductor (NASICON)-type Na(3)Zr(2)Si(2)PO(12) (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO(3) glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na(2)ZrSi(2)O(7), ZrO(2), and NaPO(3) glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na(+) ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO(3) glass has a great contribution to the Na(+) diffusion at the grain boundaries.