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 O⋅ n /2(Fe 1− y Co y ) 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.