NMR and XRD study of the influence of the P precursor in sol-gel synthesis of NASICON powders and films

NASICON (Na3Zr2Si2PO12) has been prepared by a sol-gel route. The progress of the reaction in the liquid has been monitored by means of 31P NMR spectroscopy. The dependence of phase formation and sintering behaviour of films and powders on sol-gel reactions and heat treatments was investigated. X-ray diffraction measurements showed the formation of monoclinic NASICON phase from 800 °C for powders and from 900 °C for films together with free ZrO2. An almost pure NASICON phase was observed in powders calcined at 1000 °C. Sintered pellets showed densities up to 98% of theoretical value. The microstructure of the samples was analysed by scanning electron microscopy.