Microstructure and Magnetic Properties of La-Ca-Co Substituted M-Type Sr-Hexaferrites with Controlled Si Diffusion

Applied Sciences

Kyoung-Seok Moon¹  Pyeong-yeol Yu²  Yong-Min Kang² 

[1] Department of Materials Engineering and Convergence Technology, School of Materials Science and Engineering, Gyeongsang National University, Jinju 52828, Korea;Department of Materials Science & Engineering, Korea National University of Transportation, Chungju 27469, Korea;

关键词: M-type hexaferrite;    magnetic properties;    microstructure;    abnormal grain growth;   

DOI  :  10.3390/app10217570

来源: DOAJ

【 摘 要 】

La-Ca-Co substituted M-type Sr-hexaferrites (Sr_0.3Ca_0.4La_0.3Fe_9.8Co_0.2O_19-δ) were prepared by a solid-state reaction using two different procedures, where the SiO₂ additive was mixed either before calcination (pre-Si) or after calcination (post-Si). At the same sintering temperature, smaller cell volumes and reduced saturation magnetization (M_s) values were obtained for samples processed with the pre-Si method than those with the post-Si method. This implied that the pre-Si method resulted in a greater degree of Si substitution into the M-type lattice and increased Fe extrusion out of the lattice. The grain growth behavior was controlled by the SiO₂ amount and sintering temperature. It was found that abnormal grains occur with a bimodal distribution in the 0.5 wt% SiO₂ samples sintered at 1240 °C, due to the increased critical driving force for growth caused by an increased amount of SiO₂ addition. The M_s and coercivity values were altered with the control of Si diffusion and abnormal grain growth. The control of the additive diffusion behavior is one of the important keys in the material design under same materials compositions.

【 授权许可】

Unknown