Preparation of acicular cobalt-containing magnetic iron oxide
    1.
    发明授权
    Preparation of acicular cobalt-containing magnetic iron oxide 失效
    针状钴磁性氧化铁的制备

    公开(公告)号:US5484628A

    公开(公告)日:1996-01-16

    申请号:US291559

    申请日:1994-08-16

    摘要: Acicular cobalt-containing magnetic iron oxides having a high coercive force and a core/shell structure and hence low temperature dependence of the coercive force are prepared by a process in which, in a first stage, surface activation is effected by means of iron(II) and cobalt ions under alkaline conditions on the iron oxide core under an inert gas atmosphere and thereafter, in a second stage, an epitactic coating of cobalt ferrite is applied, which coating is formed oxidatively from iron (II) and cobalt (II) hydroxide, likewise under alkaline reaction conditions. The total amount of cobalt ions used for doping remains unchanged compared with the known doped iron oxides or is even smaller. In the second process stage, the achievable coercive force can be controlled by the proportion of air in the gas mixture during the formation of the epitactic coating.

    摘要翻译: 通过一种方法制备具有高矫顽力和核/壳结构并因此矫顽力的低温依赖性的针状含钴磁性氧化铁,其中在第一阶段中,通过铁(II)进行表面活化 )和钴离子在碱性条件下在惰性气体气氛下在氧化铁芯上,然后在第二阶段施加钴铁氧体的中空涂层,该涂层由铁(II)和氢氧化钴(II)氧化形成 ,同样在碱性反应条件下。 用于掺杂的钴离子的总量与已知的掺杂的氧化铁相比保持不变,或甚至更小。 在第二工艺阶段,可以通过在形成外延涂层期间气体混合物中的空气比例来控制可实现的矫顽力。