Mn이 치환된 M형 Sr-육방정페라이트의 합성과 특성 평가

Mn-substituted M-type Sr-hexaferrites, SrFe12xMnxO19 (x = 0, 2, 4, 6, 8, 10, 12) were prepared using the sol-gel and post-annealing processes. XRD analysis on x = 0 sample revealed that the crystalline M-type hexaferrite phase can be formed at the post-annealing temperature, Tann  700 oC. The sol-gel processed powders of SrFe12xMnxO19 (x = 0, 2, 4 , 6, 8 , 10, 12) annealed a t 900 oC were ground, pressed into pellets, and sintered in air at 1100 and 1200 oC for 4 h, respectively. Single M-type hexaferrite phase is formed in samples of x  8 sintered at 1100 oC, while it is found in the samples of x  6 sintered at 1200 oC. Scanning electron microscope (SEM) was used for the study of microstructure. For the samples sintered at 1100 oC, as increase of x from 0 to 6, the resistivity significantly decreases from 1.8 × 108 ‧cm to 5.5 × 103 ‧cm, the saturation magnetization value decreases and the coercivity increases. Complex permittivity and permeability were measured on the toroidal shaped samples of SrFe12xMnxO19 (x = 0, 2, 4, 6, 8)- epoxy (10 wt%) composites. The effects of Mn substitution on the electrical and magnetic, and high frequency properties of the Mtype Sr-hexaferrites are discussed.