TY - JOUR
T1 - Ferromagnetic Co/SiO2 core/shell structured nanoparticles prepared by a novel aqueous solution method
AU - Lu, Xuegang
AU - Liang, Gongying
AU - Sun, Zhanbo
AU - Zhang, Wei
PY - 2005/3/15
Y1 - 2005/3/15
N2 - Magnetic Co nanoparticles coated with silica were successfully synthesized using a novel aqueous solution method, and their structures and properties were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The experimental results showed that the size and the shape of the particles varied with the molar content of SiO 2, reducing time and temperature. There was an optimum reducing time matching with SiO2 content at a certain reducing temperature. With the increase of SiO2 content, the reducing time should be increased too. The insulating layer of SiO2 can hinder nanoparticles from growing up. Two kinds of structures, f.c.c. Co and h.c.p. Co, could be found in the particles. The smaller the Co particles, the easier to obtain f.c.c. Co structure. And with increasing the reducing time and particles' growing up, h.c.p. Co structure appeared. The spherical-shaped particles with average size about 10-150 nm were dominant in these samples. However, some needle-shaped particles, which were about 70 nm long and 10 nm in diameter, also appeared in the samples with high SiO2 content. A relatively high saturation magnetization, 110-130 emu/g or so, was obtained when the molar content of SiO2 was from 3 to 15 mol%. The least coercivity of Co/SiO 2 nanoparticles appeared in the sample with 8 mol% SiO2, herein, the structure of particles was f.c.c. and the shape was spherical. With the increase of h.c.p. structure in the particles, the coercivity of nanoparticles increased.
AB - Magnetic Co nanoparticles coated with silica were successfully synthesized using a novel aqueous solution method, and their structures and properties were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The experimental results showed that the size and the shape of the particles varied with the molar content of SiO 2, reducing time and temperature. There was an optimum reducing time matching with SiO2 content at a certain reducing temperature. With the increase of SiO2 content, the reducing time should be increased too. The insulating layer of SiO2 can hinder nanoparticles from growing up. Two kinds of structures, f.c.c. Co and h.c.p. Co, could be found in the particles. The smaller the Co particles, the easier to obtain f.c.c. Co structure. And with increasing the reducing time and particles' growing up, h.c.p. Co structure appeared. The spherical-shaped particles with average size about 10-150 nm were dominant in these samples. However, some needle-shaped particles, which were about 70 nm long and 10 nm in diameter, also appeared in the samples with high SiO2 content. A relatively high saturation magnetization, 110-130 emu/g or so, was obtained when the molar content of SiO2 was from 3 to 15 mol%. The least coercivity of Co/SiO 2 nanoparticles appeared in the sample with 8 mol% SiO2, herein, the structure of particles was f.c.c. and the shape was spherical. With the increase of h.c.p. structure in the particles, the coercivity of nanoparticles increased.
KW - Aqueous solution method
KW - Co/SiO nanoparticle
KW - Magnetic properties
UR - https://www.scopus.com/pages/publications/13544261391
U2 - 10.1016/j.mseb.2004.11.012
DO - 10.1016/j.mseb.2004.11.012
M3 - 文章
AN - SCOPUS:13544261391
SN - 0921-5107
VL - 117
SP - 147
EP - 152
JO - Materials Science and Engineering: B
JF - Materials Science and Engineering: B
IS - 2
ER -