Modified dielectric and magnetic properties of Fe and Co substituted TbMnO3 nanoparticles

Abstract Structural, dielectric, electric impedance and magnetic properties of TbMn 1- x Co x O 3 and TbMn 1- x Fe x O 3 ( x  = 0.1 and 0.2) nanoparticles (NPs) prepared by the sol-gel method have been studied. Room temperature x-ray diffraction (XRD) patterns reveal formation of the pure crystalline orthorhombic phase. Transmission electron microscopic images of doped samples show particles with average size of 30 nm. Temperature dependent dielectric curves of all samples exhibit an increment of dielectric constant and loss with increase in doping concentration. Frequency dependent impedance spectra and Cole-Cole plots of all samples corroborate the presence of grain and grain boundary relaxations and their temperature dependence follow the Arrhenius relation. Temperature dependent magnetization curve of each sample exhibits antiferromagnetic ordering of both Tb and Mn moments. Magnetic hysteresis loops (at 5 K) of all samples show reduction in magnetization value in the doped samples. Conversely, coercivity is found to increase after Co and Fe doping.