Low temperature synthesis of NaSICON NaZr2(PO4)3 powders with the assistance of in situ formed mineralizer

A new approach was developed to prepare NaZr2(PO4)3 (NZP) powders at low temperature of 330°C. The effect of different molar ratios of ZrO(NO3)2 • xH2O to NaH2PO4 • 2H2O on the synthesis of NZP powders was systematically investigated by XRD, FE-SEM, TEM, EDS and Raman spectroscopy. The mineralizer NaNO3 was formed in situ due to the mechanochemical reaction between raw materials ZrO(NO3)2 • xH2O and NaH2PO4 • 2H2O during the grinding process. When the optimal molar ratio of Zr:P = 2:6 was used, the NZP powders with high crystallinity, good dispersity and particle sizes in the range of 500-700 nm were obtained. The dense NZP ceramics was obtained by sintering at 1100 °C for 3 h with 2 wt.% ZnO as the sintering aid. The relative density and Vickers hardness of the sintered ceramics reached 93.4% and 704MPa, respectively.