Impact of Ni doping on the morphological, electrical and dielectric properties of YMn0.4Fe0.6-xNixO3 (0 ≤ x ≤ 0.1) multiferroics

The impact of Ni doping on the morphological, electrical and dielectric properties in a polycrystalline sample of YMn0.4Fe0.6O3 was investigated. SEM analysis reveals that grain size increases with the rise of Ni concentration in YMn0.4Fe0.6-xNixO3 (x = 0, 0.05, 0.075 and 0.1) nanoparticles up to x = 0.075. The DC conductivity results indicate that all samples exhibit semiconductor behavior over the whole studied temperature range (240–440 K). In addition, the σDC curves show that the conductivity follows the same trend of the grain size with doping. AC conductivity measurements (σAC) are found to obey to Jonscher's universal power law. Actually, the results show that non-overlapping small polaron tunneling (NSPT) is the suitable model that helps to understand the conduction mechanism in our samples. Moreover, the contribution of both grain and grain boundaries in the conduction process is proved by Nyquist spectra which were fitted by an appropriate equivalent circuit. Based on dielectric measurements, it is found that dielectric losses are ruled by the DC conduction process.