Abstract

The cubic Co_0.55Ni_0.4Nd_xFe_2.05–xO₄ (0 ≤ x ≤ 0.12) ferrites are synthesized by thermal decomposition of metal oxalates at 900 °C, and subsequently reduced at 550 °C in 5% H₂–Ar ambient to obtain the Co_0.55Ni_0.4Nd_xFe_2.05–xO₄/Co composites. X-ray diffraction patterns of Co_0.55Ni_0.4Nd_xFe_2.05–xO₄ samples confirm the co-existence of the main spinel CoFe₂O₄ and trace amounts of impurity NdFeO₃ and Fe₂O₃ phases. After being reduced, impurity NdFeO₃ and Fe₂O₃ phases disappear, a new reduction product cobalt (Co) phase appears. All Co_0.55Ni_0.4Nd_xFe_2.05–xO₄/Co composites exhibit a typical single-phase magnetic behavior, suggesting the existence of exchange-coupling. Compared with Co_0.55Ni_0.4Nd_xFe_2.05–xO₄, the specific saturation magnetization of composites increases markedly from 55.05 (Co_0.55Ni_0.4Nd_0.04Fe_2.01O₄ calcined at 900 °C) to 70.04 emu/g (Co_0.55Ni_0.4Nd_0.04Fe_2.01O₄/Co reduced for 30 min), accompanied with a relatively small decrease of coercivity from 622.98 to 579.94 Oe. Exchange-coupling effect in Co_0.55Ni_0.4Nd_xFe_2.05–xO₄/Co composites is confirmed by the switching field distribution curves further.

中文翻译：

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交换耦合的硬/软Co 0.55 Ni 0.4 Nd x Fe 2.05–x O 4 / Co复合材料的成分依赖性磁性能

摘要

立方钴_0.55镍_0.4的Nd _X铁_{2.05- X} Ø ₄（0≤  X  ≤0.12）铁氧体通过的金属草酸盐热分解在900℃下合成的，并且在550℃下在5％H随后减少₂ -Ar环境获得Co _0.55 Ni _0.4 Nd _x Fe _{2.05- x} O ₄ / Co复合材料。Co _0.55 Ni _0.4 Nd _x Fe _{2.05– x} O ₄样品的X射线衍射图证实了主尖晶石CoFe ₂的共存O ₄和痕量的NdFeO ₃和Fe ₂ O ₃杂质相。还原后，杂质NdFeO ₃和Fe ₂ O ₃相消失，出现了新的还原产物钴（Co）相。所有的Co _0.55 Ni _0.4 Nd _x Fe _{2.05– x} O ₄ / Co复合材料均表现出典型的单相磁行为，表明存在交换耦合。与Co _0.55 Ni _0.4 Nd _x Fe _{2.05– x} O _4相比，复合材料的比饱和磁化强度从55.05（在900°C下煅烧的Co _0.55 Ni _0.4 Nd _0.04 Fe _2.01 O ₄）显着增加到70.04 emu / g（Co _0.55 Ni _0.4 Nd _0.04 Fe _2.01 O ₄ / Co降低30分钟） ），同时矫顽力从622.98 Oe降低到579.94 Oe。通过开关场分布曲线进一步证实了Co _0.55 Ni _0.4 Nd _x Fe _{2.05– x} O ₄ / Co复合材料中的交换耦合效应。