EP 0302912 A4 19900410 - PROCESS FOR PREPARATION OF MONODISPERSED BARIUM CONTAINING FERRITES.
Title (en)
PROCESS FOR PREPARATION OF MONODISPERSED BARIUM CONTAINING FERRITES.
Title (de)
VERFAHREN ZUR HERSTELLUNG MONODISPERGIERTER, BARIUM ENTHALTENDER FERRITE.
Title (fr)
PROCEDE DE PREPARATION DE FERRITES CONTENANT DU BARIUM MONODISPERSE.
Publication
Application
Priority
US 389987 A 19870116
Abstract (en)
[origin: WO8805337A1] An improved process for preparation of well-defined monodispersed colloidal particles of barium containing ferrites. This process involves the formation of colloidal barium ferrite particles in aqueous media by phase transformation of a ferrous hydroxide gel in the presence of barium ions. In this process, a magnetite is initially formed in aqueous solution and barium substituted into the resultant particle by displacement of Fe<2+>. This procedure is performed in a nonoxidizing atmosphere and under mildly caustic conditions. As the reaction proceeds to completion (aging) the system becomes decidedly more acidic. The colloidal particles produced in accordance with this invention are easily dispersible in aqueous media and, unlike magnetite, are superparamagnetic in response to a magnetic field. This procedure is in sharp contrast to more traditional methods of solid state transformations of the magnetite to ferrite at temperatures typically in excess of 1000 DEG C.
IPC 1-7
IPC 8 full level
A61K 9/50 (2006.01); B01J 13/00 (2006.01); B03C 1/01 (2006.01); C01G 49/00 (2006.01); C04B 35/26 (2006.01); H01F 1/44 (2006.01)
CPC (source: EP)
A61K 9/5094 (2013.01); B03C 1/01 (2013.01); C01G 49/0036 (2013.01); C04B 35/2683 (2013.01); H01F 1/445 (2013.01); C01P 2004/38 (2013.01); C01P 2004/52 (2013.01); C01P 2004/62 (2013.01); C01P 2006/42 (2013.01); C01P 2006/60 (2013.01)
Citation (search report)
- [XP] JOURNAL OF CELLULOID AND INTERFACE SCIENCE, vol. 117, no. 2, June 1987, pages 593-595, Academic Press, Inc.; "Uniform colloidal barium ferrite particles"
- [AP] JOURNAL OF THE AMERICAN CERAMIC SOCIETY, vol. 71, no. 1, January 1988, pages C60-C62, Westerville, OH, US; X.-J. FAN et al.: "Preparation of uniform colloidal strontium ferrite particles"
- See references of WO 8805337A1
Designated contracting state (EPC)
AT BE CH DE FR GB IT LI LU NL SE
DOCDB simple family (publication)
WO 8805337 A1 19880728; AU 1222988 A 19880810; EP 0302912 A1 19890215; EP 0302912 A4 19900410; JP H01503623 A 19891207
DOCDB simple family (application)
US 8800083 W 19880114; AU 1222988 A 19880114; EP 88901364 A 19880114; JP 50634887 A 19880114