In this work, samples of NASICON ceramics were synthesized by pyrolysis of organic solutions in rosin melt from Zr-deficient precursors. The phase composition, morphology and material characteristics were studied using X-ray phase analysis, scanning electron microscopy and electrochemical impedance spectroscopy. The results of the work indicate that when the zirconium concentration in the initial mixture decreases, part of the superstoichiometric elements Na, Si, P are incorporated into the crystal lattice of the main phase of NASICON, and part create an amorphous phase at the grain boundaries. It is shown that the key factor for optimizing the functional characteristics of NASICON ceramics is the absence of impurity crystalline phases, obtaining a crystal structure that maximally corresponds to the composition of NaZrSiPO, as well as the presence of an amorphous phase that promotes dense sintering of the material. The compositions in which the zirconium concentration was reduced to 20 mol. % were studied. It was found that the maximum values of conductivity have the sample with zirconium deficiency of 5 mol. %.
D. N. Grishchenko (Wed,) studied this question.