Modulation of dielectric and magnetic ordering of DyFeO3 system with Fe-site doping

Abstract

In this attempt, dysprosium orthoferrite (DyFeO3) system is explored to investigate dielectric and magnetic ordering by modulating ferrites structure using Ni and Co-dopants in place of Fe. X-ray diffraction (XRD) study confirms the formation of single-phase materials; dopants effect on modifications of atomic-scale structural parameters like lattice parameters, Fe–O bond angles, and O–Fe–O bridging angles are extracted from Rietveld refinement. Microstructural features of sintered pellet of DFO system exhibits compacted sample having grain size around 100 nm. Frequency and temperature- dependent dielectric studies depict systematic decrease of dielectric constant and loss with temperature for almost all systems. Moreover, it is found that dielectric constant and loss increases by doping; for Co and Co-Ni co-dopants the effect is maximum. Temperature profile of dielectric constant of DFO system is found to exhibit relaxor behavior. A real part of impedance as a function of frequency indicates the values of Z′ coincides with high frequency, indicates reduction of barrier potentials at high frequency due to increase in AC-conductivity. Low-frequency resistance of doped systems is lower than DFO, except Co-doped DFO. Impedance loss spectra reveal relaxation behavior of the system, which is influenced by dopants. Relaxation frequency of Ni-doped and Ni-Co codoped DFO is found shifting toward higher frequency side than DFO and DCFO systems; indicate charge relaxation is faster in DNFO and DNCFO than DFO and DCFO systems. However, activation energy of charge relaxation is found lowest for DCFO system. Same trends are revealed from Modulus spectra. Conductivity mechanisms are revealed from a combined plot of M′′(f) and –Z′′(f) as a function of frequency and corresponding relaxation process. The results conclude that conductivity in DFO and Ni-doped DFO system is dominated by delocalized motion of charge carriers, while DCFO and DNCFO systems are due long-range motion. Magnetic hysteresis (M-H) curve shows the presence of a canted antiferromagnetic ordering matrix within weak Ferromagnetic components. Coercivity of doped DFO is greated than pure DFO.