Process-optimization for preparing high coercivity modified magnetite particles

Author

Chin, Tsung-Shune ; Deng, Ming-Cheng ; Lin, Cheng-Hsiung

Author_Institution

Dept. of Mater. Sci. & Eng., Tsing Hua Univ., Hsinchu, Taiwan

Volume

29

Issue

6

fYear

1993

fDate

11/1/1993 12:00:00 AM

Firstpage

3631

Lastpage

3633

Abstract

The dependence of magnetic properties on composition and processing of nonacicular, Co, Mn and Zn modified magnetite particles obtained by coprecipitating from aqueous solutions and heat treatment was explored. It was found that a coercivity of 700 to 1700 Oe, a saturation (at 20 kOe) and residual magnetization of 79 to 87 cmu/g and 40 to 52 cmu/g, respectively; a squareness ratio of 0.48 to 0.63 can be adjustable by doping amount and heat treatment. Zn was found to raise the saturation magnetization and lower the temperature coefficient of coercivity (TCC). The heat treatment at its precursor magnetic phase state before final reduction significantly enhances the coercivity of the final magnetic phase after reduction. Due to the large coercivity, high magnetization, and low TCC value, these particles may find applications in high density recording

Keywords

X-ray diffraction examination of materials; annealing; coercive force; ferrites; magnetic hysteresis; magnetic properties of fine particles; magnetic recording; magnetisation; materials preparation; particle size; spectrochemical analysis; transmission electron microscope examination of materials; 25 to 150 C; 300 C; 320 C; 340 C; 360 C; FeMnCoZn-Fe₃O₄; TEM; X-ray diffraction; annealing; aqueous solutions; composition dependence; coprecipitation; heat treatment; high coercivity modified magnetite particles; high density recording; inductively coupled plasma spectroscopy; magnetic properties; magnetic recording; nonacicular magnetite particles; particle size; precursor magnetic phase state; process optimisation; residual magnetization; saturation magnetization; squareness ratio; temperature coefficient of coercivity; Audio recording; Coercive force; Heat treatment; Magnetic recording; Magnetosphere; Perpendicular magnetic recording; Saturation magnetization; Temperature; Video recording; Zinc;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.281252

Filename

281252