Magnetic properties of hard-soft SrFe₁₀Al₂O₁₉/Co_0.8Ni_0.2Fe₂O₄ ferrite synthesized by one-pot sol-gel auto-combustion

SrFe₁₀Al₂O₁₉/Co_0.8Ni_0.2Fe₂O₄ hard/soft nanocomposite ferrites with different content of soft phase have been prepared by simple one-pot sol-gel auto-combustion route. X-ray diffraction (XRD), field emission scanning electron microscopy and vibrating ample magnetometer were employed to analysis of structural and magnetic features of synthesized samples. XRD patterns reflect the formation of hard/soft composites of ferrites without the existence of any kind of secondary phases. Narrow size distributions of particles were formed by sol-gel method. Single smooth hysteresis loops of nanocomposites show the presence of exchange coupling between hard and soft phases. Nanocomposite with 15 wt% of soft phase reaches the highest M_r/M_s ratio of 0.63. Compared to the physical mixing of hard/ soft nanocomposites, the one-pot sol-gel auto-combustion method could be considered as a suitable method for synthesizing exchange coupled magnet.