FORMATION OF SODIUM ZIRCONIUM SILICOPHOSPHATE WITH THE STRUCTURE NaZrSiPO FROM A Zr-DEFICIENT PRECURSOR

Samples of NASICON glass-ceramics were synthesized by pyrolysis of a mixture of organic solutions in molten rosin. The article discusses the phase formation, morphology and characteristics of the obtained silicophosphates. The composition formed from the precursor with the molar ratio of components Na : Zr : Si : P equal to 3 : 1.33 : 2 : 1 was selected for study. The effect of additional amounts of phosphorus on the phase composition of the sample was studied. It was found that the precursor of the composition 3 : 1.33 : 2 : 1.15 forms densely sintered glass-ceramics containing a crystalline phase of the composition NaZrSiPO. The composition of the product is confirmed by the unit cell parameters calculated by the Rietveld method. The samples were obtained at a temperature of 1000 and 1100°С without pressing and have densities of 85 and 88% of the theoretical value, respectively. It was concluded that Na, Si, P not included in the crystal lattice participate in the formation of the X-ray amorphous phase and provide conditions for the formation of NASICON by the type of liquid-phase sintering. A comparative characteristic of the properties of the NaZrSiPO composition obtained from Zr-deficient and non-deficient precursors was carried out. It is shown that the glass phase formed in the intergranular space of Zr-deficient samples negatively affects the conductivity values of the material.