Effect of Mg substitution on structure and magnetic properties of Ni_0·25Cu_0·3Zn_0·45Fe₂O₄ ferrites synthesised by NaOH coprecipitation method

Abstract

Ni_0·25−xMg_xCu_0·3Zn_0·45Fe₂O₄ (for x = 0, 0·05, 0·1, 0·2 and 0·25) ferrites have been synthesised by NaOH coprecipitation method. The X-ray diffraction patterns of these ferrites confirmed the formation of the single phase spinel structure. The lattice constant was found to increase with Mg content obeying Vegard’s law. The crystallite size of these samples varies from 13·2 to 16·4 nm. The bulk density ρ_B decreases with increasing Mg concentration. And scanning electron microscopy images show no obvious differences among all samples with different Mg concentration. With increasing Mg content, the initial permeability monotonously increases while the cutoff frequency f_r gradually decreases, which agrees well with Snoek’s law. Moreover, saturation magnetisation M_s and the Curie temperature T_c continuously decrease with increasing Mg content but no noticeable variation in quality factor Q with Mg content is observed.

Keywords:

• NiMgCuZn ferrites
• NaOH coprecipitation
• Initial permeability
• Curie temperature
• Saturation magnetisation
• Cutoff frequency
• Quality factor

This work was supported by National Natural Science Foundation of China (under grant no. 51271130) and Natural Science Foundation of Tianjin (under grant no. 12JCYBJC11400).