Structure, conductivity, dielectric properties, and charge-carrier dynamics of lead-free Dy2NiMnO6 double perovskite

This work investigates the structure and electrical properties of Dy2NiMnO6 prepared via low-temperature auto-ignition method. Dy2NiMnO6 exhibits monoclinic structure with space group P2(1)/n. The crystal structure of Dy2NiMnO6 is discussed in detail. The conductivity enhances significantly with temperature indicating semiconductor nature of the sample. The values of activation energies depend on temperature regions, but in the entire temperature range, the conduction mechanism follows overlapping large-polaron tunneling model. The phase angle depends significantly on both temperature and frequency. The dielectric properties exhibit relaxor-type behavior. The relaxor ferroelectric behavior of Dy2NiMnO6 increases with the frequency. The values of activation energy for conduction, hopping, migration, and relaxation are in the range of 0.22 - 0.25 eV (<= 125 degrees C), 0.64 - 0.66 eV (150 - 325 degrees C) and 0.63 - 0.65 eV (>= 350 degrees C). The values of all activation energies are very similar. The scaling behavior of conductivity, impedance, and modulus obeys time-temperature superposition principle and scaling formalism completely. The conduction, migration, and relaxation mechanisms remain same in the entire temperature range.