Title :
Acicular γ-Fe2O3 particles surface-coated with barium ferrite
Author :
Deng, M.C. ; Hsu, S.L. ; Chin, T.S.
Author_Institution :
Dept. of Mater. Sci. & Eng., Tsing Hua Univ., Hsinchu, Taiwan
fDate :
9/1/1992 12:00:00 AM
Abstract :
Acicular γ-Fe2O3 particles surface-coated with barium ferrite (BF) have been prepared by reacting acicular α-FeOOH and surface-absorbed Ba++ at 810 to 890°C followed by reduction-oxidation. The BF-coated γ-Fe2O3 has a diameter of 100 to 200 nm and aspect ratio of 3 to 8, a coercivity of 330 to 3600 Oe, and a saturation and residual magnetization of 47 to 70 and 23 to 34 emu/g, respectively, by controlling the Ba++ concentration and heat treatment temperatures. They have an extremely low temperature coefficient of coercivity of -0.07 to -0.1%/°C. These particles are potentially useful for high-density recording purposes
Keywords :
barium compounds; coercive force; ferrites; heat treatment; magnetic properties of fine particles; magnetic tapes; magnetisation; surface treatment; 810 to 890 C; BaFe12O19 coating; acicular gamma Fe2O3 particles; aspect ratio; coercivity; heat treatment temperatures; high-density recording; magnetic tape; reduction-oxidation; residual magnetization; saturation magnetisation; surface-coated; Audio recording; Barium; Calcination; Coercive force; Ferrites; Filtering; Magnetic analysis; Plasma measurements; Plasma temperature; Saturation magnetization;
Journal_Title :
Magnetics, IEEE Transactions on
