Influence of Ba Substitutions on Microstructure and Magnetic Properties of La-Ca-Co System Permanent Ferrite

La(0.6)Ca(0.4-x)Ba(x)On/2(Fe1-yCoy)(2)O-3(x =0, 0.05, 0.1, 0.15 and 0.2) permanent ferrite materials were prepared by ceramic technique. The topography and the structure were characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD), respectively. The magnetic properties were measured using vibrating sample magnetometer (VSM) and digital magnetometer. Single M-phase and flake-like grains were obtained for samples without Ba substitution(x =0), and the magnetic properties of the pre-sintering La-Ca-Co ferrite were as follows: B-r =440 mT, H-cb =296 kA/m, H-cj =426 kA/m, (BH)(max) =36.6 kJ/m(3) and H-k/H-cj =0.83. When Ca was substituted by Ba, pre-sintered powder presents single M-phase structure and close three-dimensional size of grains, resulting in an improved rectangle ratio of sintered magnet. The rectangle ratio of sintered magnet reaches a maximum of 0.93 when x =0.1. By optimizing process parameters, M-type La-Ca-Ba-Co sintered magnet was prepared with B-r =445 mT, H-cb =337 kA/m, H-cj =420 kA/m, (BH)(max) =38.6 kJ/m(3) and H-k/H-cj =0.95.