Title :
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
fDate :
11/1/1993 12:00:00 AM
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;
Journal_Title :
Magnetics, IEEE Transactions on
