Na9In(MoO4)6: synthesis, crystal structure, and Na+ ion diffusion

Fundamental studies of the materials with fast sodium mobility are important for the development of energy storage systems. This article presents the results of experimental studies of Na-conducting oxide Na9In(MoO4)6. This compound crystallizes in rhombohedral symmetry with the space group R $$\overline{3}$$ c and the unit cell parameters: a = 15.08695(6) and c = 19.1701(2) A. Impedance spectroscopy measurements show that Na9In(MoO4)6 is an ionic conductor with a conductivity of about 2.1 × 10−2 Sm·cm−1 at 803 K. The 23Na NMR data reveal the coexistence of three types of sodium motion. These motional processes are activated at different temperatures and are characterized by substantially different nature and dynamics characteristics.