Microstructure, AC impedance and DC electrical conductivity characteristics of NiFe2-xGdxO4 (x = 0, 0.05 and 0.075)

TLDR: The structure and electrical properties of Gd doped Ni ferrite materials, namely NiFe1.95Gd0.05O4 and NiFe 1.075O4, are reported to demonstrate their improved electrical properties compared to that of pure NiFe2O4 as discussed by the authors.

Abstract: The structure and electrical characteristics of Gd doped Ni ferrite materials, namely NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4, are reported to demonstrate their improved electrical properties compared to that of pure NiFe2O4. NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount of GdFeO3 additional phase while pure NiFe2O4 crystallize in inverse spinel phase without any impurity phase. The back scattered electron imaging analysis indicate the primary and secondary formation in NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds. Atomic force microscopy measurements indicate that the bulk grains are ∼2-5 micron size while the grain boundaries are thin compared to bulk grains. Impedance spectroscopic analysis at different temperature indicates the different relaxation mechanisms and their variation with temperature, bulk grain and grain-boundary contributions to the electrical conductivity (Rg) and capacitance (Cg) of these materials. The con...