Magnetic and microstructural features of Dy3+ substituted NiFe2O4 nanoparticles derived by sol-gel approach

This study explored the microstructural and magnetic features of NiFe2-xDyxO4 (x <= 0.10) NPs (nanoparticles) that were synthesized by sol-gel auto-combustion method. The single phase of spinel ferrite has been verified for all samples without any impurity. The cubic morphology of the products was also showed by SEM. Room temperature (300 K) and 10 K magnetization curves were recorded applying a dc magnetic field up to +/- 50 kOe and it was observed that magnetic features of NiFe2O4 NPs significantly changed by the substitution of Dy3+ ion. Magnetization measurements showed low order of 300 and 10 K magnetic parameters (such as K-eff, coercivity and anisotropy field values), revealing soft ferrimagnetic behaviors of all pristine and doped NiDyxFe2-xO4 (0.00 <= x <= 0.10) NPs at both 300 and 10 K. Pristine NiFe2O4 has maximum magnetic moment and saturation magnetization values among all samples. Dy3+ substitution showed a slight decrement in magnetization values compared with pristine sample. A slight increase in coercivity was noticed with Dy3+ substitution. Squareness ratios (SQRs) have a range between 0.144 and 0.324. These values are smaller than the theoretical limit of 0.50, implying the multi-domain nature for NPs. Blocking temperature (T-B) was calculated as 28 K for NiFe2O4 NPs. Pure phase of NiDyxFe2-xO4 (0.00 <= x <= 0.10) nanoparticles were prepared via sol-gel auto-combustion process. The structure, morphology, and magnetic properties were investigated.