Synthesis and Ionic Conductivity of NaZr2(AsO4)x(PO4)3 –x

Arsenate phosphates NaZr2(AsO4)x(PO4)3 –x are synthesized by the sol–gel method with subsequent annealing at 1123 K. Thus obtained specimens are investigated using X-ray diffraction analysis, IR and impedance spectroscopy. In the NaZr2(AsO4)x(PO4)3 –x system, continuous solid solution (0 ≤ x ≤ 3) with NaZr2(PO4)3 (NASICON) structure forms. According to the impedance spectroscopy data, an increase of the content of arsenic in the NaZr2(AsO4)x(PO4)3 –x system leads to an increase of the sodium-ionic conductivity; for NaZr2(AsO4)3, it reaches 8 × 10–5 S/cm at 773 K. At the same time, the activation energy of conductivity of this material (50 ± 1 kJ/mol) appears to be twice lower than the activation energy of conductivity of NaZr2(PO4)3 (100 ± 1 kJ/mol).