Ti⁴⁺掺杂M型六角铁氧体BaFe_12-xTi_xO₁₉陶瓷的磁学和介电特性

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 BaFe_12-xTi_xO₁₉ (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 BaFe_12-xTi_xO₁₉ 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 BaFe_12-xTi_xO₁₉ ceramics appear obvious low frequency dielectric enhancement accompanied by a Maxwell-Wagner dielectric relaxation.