Dielectric Relaxation and Non‐Overlapping Small Polaron Tunneling Model Conduction Studies of Ag2‐xNaxZnP2O7 (x = 0, 1, and 2) Materials

The Ag2−xNaxZnP2O7 (x = 0, 1, and 2) materials are prepared using the solid–solid method followed by heat treatment. The investigated samples are characterized by combining X‐ray powder diffraction and electrical impedance spectroscopy techniques. The Rietveld refinement of the X‐ray diffraction (XRD) pattern revealed that these Ag2ZnP2O7, AgNaZnP2O7, and Na2ZnP2O7 compounds are indexed in the tetragonal system with the P42/n space group. Their dielectric properties are measured in the frequency and temperature ranges of 200–107 Hz and 419–518 K, respectively. In these compounds, the dielectric relaxation can be described by a Cole–Cole model. The frequency dependence of the conductivity is interpreted in terms of Jonscher's law. For the three compounds, the activation energy for conduction has a different value compared to the activation energy for the relaxation process. This indicates that the conduction in the compound is not predicted by the simple hopping model. Then, the temperature dependence of the power‐law exponent(s) suggests that the non‐overlapping small polaron tunneling model is the dominant transport process in these materials. Moreover, the values of defect states N(EF) and the tunnel distance RW show the electrical performance of the Ag2ZnP2O7 compound. By the substitution of monovalent cations (Ag or Na) in the Zn2P2O7 compound, the conductivity mechanism changes from a correlated barrier hopping model to a non‐overlapping small polaron tunneling model. Moreover, the values of defect states N(EF) and the tunnel distance RW show the electrical performance of the Ag2ZnP2O7 compound.