Structural transformations and ionic mobility in CsSbF<sub>3</sub>(H<sub>2</sub>PO<sub>4</sub>)
<sup>1</sup>H, <sup>19</sup>F, <sup>31</sup>P NMR, DSC, and XRD methods were used to study ionic mobility and structural transformations in the CsSbF<sub>3</sub>(H<sub>2</sub>PO<sub>4</sub>) compound (I). Radical changes in <sup>1</sup>H, <sup>19</sup>F, <sup>31</sup>P NMR spectra above 390 K are associated with a crystalline disordered phase which forms in I at 400-420 K. This phase demonstrates high ionic mobility and further transforms (above 425 K) into the amorphous (glassy) phase. We have determined the types of ionic mobility in this compound and in its amorphous product. According to the NMR data, the diffusion in the proton sublattice of the disordered and amorphous phases proceeds even at room temperature.