Magnetic and Dielectric Properties of Ti4+-doped M-type Hexaferrite BaFe12–xTixO19 Ceramics

Abstract: Hexaferrite system is expected to be applied in various kinds of multi-state memories, magnetoelectric sensors and other new microelectronic devices, due to its high temperature magnetoelectric coupling effect with low field. Not only the B-site doping of M-type hexaferrite BaFe12O19 with Ti4+ ion can change its magnetic structure
and magnetic properties, but also the defects, multivalent Fe ions, introduced by B-site non-epuivalent Ti doping, could affect its electric properties. In this study, M-type hexaferrite BaFe12–xTixO19 (x=0, 0.5, 1, 1.5) ceramics were prepared by solid phase sintering. The effects of Ti4+ doping on the structural, magnetic and dielectric properties were studied. The results show that BaFe12–xTixO19 is in ferrimagnetic order with antiparallel spins. When the doping concentration of Ti4+ ions is low, it tends to replace Fe3+ ions with up-spin. And the magnetization decreases with the increase of Ti dopant. However, with the further increase of Ti4+ doping, Fe3+ ions with down-spin is also replaced, and the saturation magnetization increases with the increase of x. The introduction of Ti4+ ions can also make the grains to be semiconductor, which results in the Maxwell-Wagner interface polarization behavior at the interfaces between semiconducting grains and grain-boundaries. Hence, M-type hexaferrite BaFe12–xTixO19 ceramics appear obvious low frequency dielectric enhancement accompanied by a Maxwell-Wagner dielectric relaxation.

Key words: B-site doping; M-type hexaferrite; magnetic property; dielectric property

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