Preparation and magnetic properties of BaFe ₁₂O ₁₉/Ni _0.8Zn _0.2Fe ₂O ₄ nanocomposite ferrite

Nanocomposite of hard (BaFe ₁₂O ₁₉)/soft ferrite (Ni _0.8Zn _0.2Fe ₂O ₄) have been prepared by the sol-gel process. The nanocomposite ferrite are formed when the calcining temperature is above 800 °C. It is found that the magnetic properties strongly depend on the presintering treatment and calcining temperature. The bee waist type hysteresis loops for samples disappear when the presintering temperature is 400 °C and the calcination temperature reaches 1100 °C owing to the exchange-coupling interaction. The remanence of BaFe ₁₂O ₁₉/Ni _0.8Zn _0.2Fe ₂O ₄ nanocomposite ferrite with the mass ratio of 5:1 is higher than a single phase ferrite. The specific saturation magnetization, remanence magnetization and coercivity are 63 emu/g, 36 emu/g and 2750 G, respectively. The exchange-coupling interaction in the BaFe ₁₂O ₁₉/Ni _0.8Zn _0.2Fe ₂O ₄ nanocomposite ferrite is discussed.