Magnetic properties of Ba–Nd–Co system M-type ferrite fine particles prepared by controlling the chemical coprecipitation method

Abstract Single phase Ba–Nd–Co M-type ferrite fine particles were prepared by the chemical coprecipitation method and subsequent heat treatment method. Optimum magnetic properties were achieved with materials of composition Ba 2+ 0.99 Nd 3+ 0.118 Co 2+ 0.041 Fe 3+ 11.86 O 2− 19 and heat treatment of 1000°C×2 h in air. The magnetic and physical properties are σ s = 80.7 × 1 0 - 6 Wb m/kg(64.2 emu/g), H cJ = 479.2 kA / m (5.99 kOe), T c = 452 ∘ C , the lattice constants a = 0.5889 nm , c = 2.318 nm , the activation energy = 295.3 kJ/mol(70.31 kcal/mol), and the average particle size = 0.15 μm. Temperature coefficient of the intrinsic coercivity (0.07%/°C) of these powder were found to be very small.