Effect of Substitutional Elements on the Natural Resonance Frequency of Barium M-Type Ferrite

摘要

The effect of substitutional elements (Ti, Sc, Zr,Ti_(0.5)M_(0.5), Zr_(0.5)M_(0.5), Sn_(0.5)M_(0.5)(whereM=Co, Ni, Zn, Mn Mg, Cu)) on the natural resonance frequencyof Barium M-type hexagonal ferrite (BeFe_(12) O_(19)) wasinvestigated, with the aim of finding a material suitable for use asa microwave absorber in the GHz range. It was found that theanisotropy field (H_A) decreases with increasing amounts ofsubstitutional element, which leads to the natural resonancefrequency (fr) and the matching frequency (fm) shifting to lowervalues. Some Ti_(0.5)M_(0.5) substituted samples exhibitedvalues of fr within the 1 to 20GHz range, and the minimumreflection loss (R.L.) for these samples was found to be less than–20dB. In particular, because of their large values of magneticloss ((#mu#")=4.6 and #mu#"=4.0), theBeFe_9(Ti_(0.5)M_(0.5))_3O_(19) samples had small matchingthicknesses (dm) of 0.58mm and 0.53mm, with matchingthicknesses (fm) of 12.35GHz and 15.75GHz, respectively.Therefore, it may be concluded that Barium M-type ferrite is acandidate for use as a microwave absorber in the GHz range.