公开(公告)号：DE3766537D1

公开(公告)日：1991-01-17

申请号：DE3766537

申请日：1987-05-07

Applicant: BASF AG

Inventor： SCHWAB EKKEHARD DR ,  STECK WERNER DR ,  SCHLOESSER WILHELM ,  FESER RAINER DR

IPC: C01G49/02 ,  C01G49/00 ,  G11B5/706 ,  G11B5/712 ,  H01F1/11

Abstract: Acicular, magnetic iron oxide consisting of a core of gamma-iron(III) oxide and a ferrite shell containing a total of from 0.4 to 12% by weight of cobalt(II) ions and from 0.1 to 15% by weight of iron(II) ions, the percentages being based on the total amount of magnetic material, is prepared by a process in which an iron(II) hydroxide precipitate is applied to the gamma-iron(III) oxide core in a first stage and an iron-(II)/cobalt hydroxide precipitate is applied to the said core in a second stage, and the core is then converted to the ferrite shell by oxidation.

公开(公告)号：DE3616096A1

公开(公告)日：1987-11-19

申请号：DE3616096

申请日：1986-05-13

Applicant: BASF AG

Inventor： SCHWAB EKKEHARD DR ,  STECK WERNER DR ,  SCHLOESSER WILHELM ,  FESER RAINER DR

IPC: C01G49/02 ,  C01G49/00 ,  G11B5/706 ,  G11B5/712 ,  H01F1/11 ,  C01G49/06 ,  C01G51/04 ,  C09C1/24 ,  C09C3/06

Abstract: Acicular, magnetic iron oxide consisting of a core of gamma-iron(III) oxide and a ferrite shell containing a total of from 0.4 to 12% by weight of cobalt(II) ions and from 0.1 to 15% by weight of iron(II) ions, the percentages being based on the total amount of magnetic material, is prepared by a process in which an iron(II) hydroxide precipitate is applied to the gamma-iron(III) oxide core in a first stage and an iron-(II)/cobalt hydroxide precipitate is applied to the said core in a second stage, and the core is then converted to the ferrite shell by oxidation.