Influence of microstructure on the magnetic properties of Li-Cu-Mg-Zn ferrites: Role of Bi2O3 addition

Influence of Bi2O3 addition on the microstructure and magnetic properties of Li-Cu-Mg-Zn ferrites having the compositions Li0.25Cu0.10Mg0.10Zn0.30Fe2.25O4 + xBi2O3 (where x  = 0.0, 0.3, 0.4, 0.6 and 0.8 wt%) have been reported in this study . The structural property has been studied with the X-ray diffraction technique, which reveals that all the samples have shown the cubic spinel phase without any impurity peak. A microstructural analysis demonstrates that the grain growth of the samples is influenced by the amount of Bi2O3 addition resulting an increase of the average grain size from 1.12 (for x = 0.0 wt%) to 2.74 µm (for x  = 0.6 wt%). The development of the grain size could be attributed to the densification of sample due to the formation of the liquid phase of Bi2O3 in the sintering process. The magnetic hysteresis measurement shows that the saturation magnetization increases from 72.1 (for x = 0.0 wt%) to 77.6 emu/g (for x  = 0.6 wt% Bi2O3). However, it declined at x  = 0.8 wt%, which may be ascribed to the dilution effect. The complex magnetic permeability measurement shows that an enhancement of the initial permeability is clearly observed with the addition of Bi2O3 content. It is inferred that a correlation has been found between the grain growth and the magnetic properties of the investigated samples. Fourier transforms infrared absorption reveals that the frequency band appears in the high frequency (539–555 cm−1) range which can be attributed to the stretching vibrations at the tetrahedral site. The band appearing in the low frequency (359–373 cm−1) range is for the octahedral site, which is due to bending vibration. The elastic constants such as bulk modulus, Young’s modulus, rigidity modulus, Poisson’s ratio and Pugh’s ratio have been calculated for all the studied samples. It shows that all synthesized samples are in ductile nature.