TY - JOUR
T1 - Synthesis and magnetic properties of core-shell structured (NiCo)O(AFM)-NiCo(FM) magnetic nanoparticles
AU - Jeyadevan, B.
AU - Chinnasamy, C. N.
AU - Perales-Perez, O.
AU - Iwasaki, Y.
AU - Hobo, A.
AU - Shinoda, K.
AU - Tohji, Kazuyuki
AU - Kasuya, A.
N1 - Funding Information:
Manuscript received February 13, 2002; revised May 21, 2002. This work was supported in part by a Grant-in-Aid for Priority Research (11165202) from the Ministry of Education, Science, Culture, and Sports of Japan and CREST of Japan Science and Technology Institute. B. Jeyadevan, C. N. Chinnasamy, A. Hobo, K. Shinoda, and K. Tohji are with Tohoku University, Sendai 980-8579, Japan (e-mail: jeya@ni4.earth.to-hoku.ac.jp). O. Perales-Perez is with the School of Metallurgy, Universidad Nacional de Ingenieria, Lima 25, Peru. Y. Iwasaki is with Sony Corporation Core Technology and Network Company, Sendai Technology Center, Tagajo-shi, Miyagi ken 985-0842, Japan. A. Kasuya is with Center for Interdisciplinary Research, Tohoku University, Sendai 980-8578, Japan. Digital Object Identifier 10.1109/TMAG.2002.803219.
PY - 2002/9
Y1 - 2002/9
N2 - We have succeeded in the synthesis of nanometer size monodispersed Ni-Co metal particles through the modified-polyol process. Ni-Co metal particles of about 40 and 100 nm with Co-rich core and Ni-rich shell were produced by the manipulation of the reaction kinetics through a suitable selection of hydroxyl ion concentration in the ethylene glycol-Ni-Co system. Furthermore, core-shell structured (NiCo)O(AFM)-NiCo(FM) was produced by oxidizing particles at 533 K in air for different times. The magnetic properties, especially the exchange-bias (HE) fields of 40 and 100-nm core-shell structured particles synthesized under similar conditions behaved differently. However, their behavior was explained considering exchange biased interactions at (NiCo)O(AFM)-NiCo(FM), and (Co)O(AFM)-Co(FM) interfaces with two different exchange coupling constants. The 40 nm particles oxidized for 4h and composed of (NiCo)O(AFM)-NiCo(FM), exhibited a maximum HE field of 36 and 201 Oe at 298 and 77 K, respectively.
AB - We have succeeded in the synthesis of nanometer size monodispersed Ni-Co metal particles through the modified-polyol process. Ni-Co metal particles of about 40 and 100 nm with Co-rich core and Ni-rich shell were produced by the manipulation of the reaction kinetics through a suitable selection of hydroxyl ion concentration in the ethylene glycol-Ni-Co system. Furthermore, core-shell structured (NiCo)O(AFM)-NiCo(FM) was produced by oxidizing particles at 533 K in air for different times. The magnetic properties, especially the exchange-bias (HE) fields of 40 and 100-nm core-shell structured particles synthesized under similar conditions behaved differently. However, their behavior was explained considering exchange biased interactions at (NiCo)O(AFM)-NiCo(FM), and (Co)O(AFM)-Co(FM) interfaces with two different exchange coupling constants. The 40 nm particles oxidized for 4h and composed of (NiCo)O(AFM)-NiCo(FM), exhibited a maximum HE field of 36 and 201 Oe at 298 and 77 K, respectively.
KW - Core-shell structured nanoparticles
KW - Exchange-bias
KW - Nanocrystalline Ni-Co particles
KW - Polyol process
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U2 - 10.1109/TMAG.2002.803219
DO - 10.1109/TMAG.2002.803219
M3 - Conference article
AN - SCOPUS:0036761973
VL - 38
SP - 2595
EP - 2597
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
SN - 0018-9464
IS - 5 I
T2 - 2002 International Magnetics Conference (Intermag 2002)
Y2 - 28 April 2002 through 2 May 2002
ER -