Towards high performance CoFe2O4 isotropic nanocrystalline powder for permanent magnet applications

We report on a comparative study of high performance isotropiccobaltferrite (CoFe2O4)powder processed by dry andsurfactant assisted (wet) ballmilling.Milling times as short as 1.5  min (dry) and 6 min (wet) have resulted in a 4-fold increase incoercivity, with a maximum achieved value above 318  kA/m (4 kOe). The use ofsurfactant is shown to be advantageous in the formation of a more homogeneous structure constituted by non-agglomerated and strained nanoparticles. A record (BH) max value of 18.6  kJ m −3 (2.34  MGOe) has been obtained for isotropicpowder after post-processing annealing. This magnetic performance combined with the required short processing times and the unnecessary requirement of oxygen avoidance in themilling process, makes this CoFe2O4powder a good candidate forpermanent magnet applications.

Source: Applied Physics Letters - November 30, 2016 Category: Physics Authors: F. J. Pedrosa, J. Rial, K. M. Golasinski, M. N. Guzik, A. Quesada, J. F. Fern ández, S. Deledda, J. Camarero and A. Bollero Source Type: research