NMR study of sol-Gel processed NASICON

NASICON powders having the Na₃Zr₂Si₂PO₁₂ composition were prepared using a sol-gel method. All the reagents used were alkoxides. The precursor solution was rapidly hydrolized in order to get a precipitate, or slowly gelated under exposure to low atmospheric humidity. The slow hydrolysis process was studied using nuclear magnetic resonance (NMR) spectroscopy in liquid phase. ¹H, ¹³C, and ³¹P NMR spectra were performed. NMR allowed us to identify the advancement of the reaction and the degree of polymerization. NASICON powders were prepared by heating both precursors at various temperatures in the range 800-1200°C for 1h. The phase evolution as a function of the decomposition temperature was investigated by X-ray diffraction (XRD) analysis. The NASICON prepared from the rapid hydrolysis contained larger amounts of zirconia, while the samples prepared from the slow hydrolysis were almost pure, showing monoclinic structure.