Effects of NiO addition on the structure and electric properties of Dy3−xNixFe5O12 garnet ferrite

Polycrystalline garnet ferrites Dy3−xNixFe5O12 with varying Ni substitutions (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by the standard ceramic technique and their crystalline structures were investigated by using X-ray diffraction and IR spectroscopy. The X-ray diffraction analysis showed that all samples have a single cubic garnet phase. The materials prepared are identified by infrared rays which indicate the presence of three absorption bands ν2, ν3 and ν4 which represent the tetrahedral, octahedral and dodecahedral sites respectively which characterize the garnet ferrite.The dielectric constant (ɛ), and dielectric loss (tan δ) of the prepared samples were measured at 1 kHz in the temperature range 300–700 K. The dielectric constant (ɛ), and dielectric loss (tan δ) are functions of temperature.The initial magnetic permeability has been studied at different temperatures. The initial magnetic permeability (μi) increases gradually with increasing temperature and then drops suddenly at a certain temperature Tc.

The initial magnetic permeability μi vs. temperature dependence can be explained: the presence of Ni concentration in the crystal lattice leads to the reorientation of the magnetization vectors Ms. This reorientation depends on the Ni content and external condition like temperature. Ms must align itself in the easy direction. Therefore the anomaly in μi curve (peaks) may be explained as a result of the rotation of the magnetization vectors Ms or due to the behavior of the crystal anisotropy constant with temperature and composition.Figure optionsDownload as PowerPoint slide