Physico-Chemical Characterization of Na3Zr2Si2PO12 Fine Powders Prepared by Sol-Gel Method Using Citrates

Abstract

Sodium superionic conductor (NASICON) powders have been prepared by sol-gel technique using citrates. The optimum pH condition (\\cong6) for sol-gel process was predicted by theoretical consideration of thermodynamic equilibrium constants for corresponding metal salts in aqueous solution. The pure NASICON phase with rhombohedral unit cell could be obtained by thermal decomposition of citrate precursors at a relatively low temperature (850°C). When the calcining temperature was raised to 1100°C, however, slight monoclinic distortion with formation of a trace of monoclinic ZrO2 was observed. Thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) technique, scanning electron microscopy (SEM) and 31P static and magic angle spinning (MAS) NMR have been used to characterize the calcined powders.