Magnetic Biomorphic BaFe12-xCrxO19 Ceramics with Multilayer Wall Structure Made from Spruce Templates

BaFe12-xCrxO19 (x = 0.0, 0.1, 0.2, 0.3, and 0.4) ferrite ceramics were prepared by a sol-gel method using spruce sapwoods as the templates. The prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and a magnetic property measurement system (MPMS). The prepared materials maintained a multilayer wall structure of spruce sapwoods. All samples presented the single-phase of the magnetoplumbite barium hexaferrite. The saturation magnetization initially increased until it reached a maximum value at x = 0.2 and then decreased in three directions (parallel cross section, parallel radial section, and parallel tangential section). The coercivity decreased monotonously when measured in three directions. However, the coercivity was obviously lower in the parallel cross section direction than in the other directions because of the structural anisotropy caused by the multilayered wall structure.