PREPARATION AND MAGNETIC STUDIES OF ACICULAR FE-CO ALLOY PARTICLES

被引:11
作者
HSU, JH [1 ]
KUO, PC [1 ]
LIN, MY [1 ]
机构
[1] NATL TAIWAN UNIV,GRAD INST MAT ENGN,TAIPEI,TAIWAN
关键词
D O I
10.1063/1.348955
中图分类号
O59 [应用物理学];
学科分类号
摘要
Acicular alpha-FeOOH particles with particle length of about 0.2-mu-m and axial ratio of about 8 were used as the starting material to prepare acicular Fe-Co alloy particles. They were made by adsorbing Co(OH)2 on the surface of alpha-FeOOH particles, followed by dehydration, annealing, and reduction. In order to prevent sintering at high temperatures, the Co-alpha-FeOOH particles were first dehydrated at 300-degrees-C and then coated with a thin layer of silica before high-temperature treatments. Furthermore, after reduction, the metallic powder was immersed in toluene to avoid oxidation. The particle structure of Fe-Co was determined from x-ray diffraction. It has been found that, up to 50 at. % Co, all the Fe-Co particles have the same bcc structure and similar lattice constant. The magnetic properties of Fe-Co alloy particles with different Co concentrations were investigated using a vibrating sample magnetometer. The specific saturation magnetizations sigma-s are about 30% below those of bulk materials. The maximum value of sigma-s at room temperature is obtained with 42 at. % Co. The coercivity that mainly originates from shape anisotropy is as high as 1250 Oe for the particles with 33 at. % Co. Furthermore, sigma-s drops sharply with Si content while H(c) peaks at 0.6% Si. The coercivities of the particles also depend on the crystallite size. H(c) shows a maximum when the crystallite size is about 300 angstrom.
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页码:4484 / 4486
页数:3
相关论文
共 8 条
[1]  
Cullity B.D., 1978, ELEMENT XRAY DIFFRAC, V2nd, P102
[2]  
CULLITY BD, 1972, INTRO MAGNETIC MAT, P146
[3]  
Ellis W., 1941, T AM SOC MET, V29, P415
[4]   ANNEALING EFFECT ON MAGNETIC-PROPERTIES OF SI-MODIFIED GAMMA-FE2O3 PARTICLES [J].
HSU, JH ;
CHANG, CR ;
KUO, PC ;
HUANG, JH .
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 1990, 89 (1-2) :167-172
[5]  
KITTEL C, 1956, SOLID STATE PHYS, V3, P437
[6]   PARTICULATE MAGNETIC RECORDING MEDIA - A REVIEW [J].
SHARROCK, MP .
IEEE TRANSACTIONS ON MAGNETICS, 1989, 25 (06) :4374-4389
[7]   FINE METAL PARTICLES HAVING SUPER HIGH COERCIVITY [J].
WATANABE, A ;
UEHORI, T ;
SAITOH, S ;
IMAOKO, Y .
IEEE TRANSACTIONS ON MAGNETICS, 1981, 17 (04) :1455-1458
[8]  
Wohlfarth E.P., 1980, FERROMAGNETIC MATERI, V2