Magnetic properties of Dy nanoparticles and Al2O 3-coated Dy nanocapsules

X. G. Liu; S. W. Or; B. Li; Z. Q. Ou; L. Zhang; Q. Zhang; D. Y. Geng; F. Yang; D. Li; E. Brück; Z. D. Zhang

doi:10.1007/s11051-010-0108-y

Magnetic properties of Dy nanoparticles and Al₂O ₃-coated Dy nanocapsules

X. G. Liu, S. W. Or, B. Li, Z. Q. Ou, L. Zhang, Q. Zhang, D. Y. Geng, F. Yang, D. Li, E. Brück, Z. D. Zhang

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

Dy₂O₃-coated Dy nanoparticles and Al ₂O₃-coated Dy nanocapsules, with Dy cores with the average size of 3.6 and 17.6 nm, respectively, are synthesized by arc-discharge technique. The transition from ferromagnetism to antiferromagnetism absents in the Dy nanoparticles, due to that its average core size of 3.6 nm is smaller than the helix period of Dy. The temperature of the superparamagnetism- antiferromagnetism transition in the Dy nanocapsules increases abnormally to 105 K, while the Néel temperature decreases to 150 K. The magnetic-entropy change (-ΔS_m) of the Dy nanoparticles rapidly increases with decreasing temperature. For Al₂O₃-coated Dy nanocapsules, -ΔS_m reaches 15.2 J kg^-1K^-1 at 7.5 K, due to the existence of superparamagnetism, and a peak (5.2 J kg^-1K ^-1) appears at 105 K due to the superparamgantism-antiferromagnetism transition, and -ΔS_m exceeds 2 J kg^-1K^-1 in the temperature range from 7.5 to 105 K, for a field change from 1 to 5 T.

Original language	English
Pages (from-to)	1163-1174
Number of pages	12
Journal	Journal of Nanoparticle Research
Volume	13
Issue number	3
DOIs	https://doi.org/10.1007/s11051-010-0108-y
State	Published - Mar 2011
Externally published	Yes

Funding

Acknowledgments This study has been supported partly by the Science Exchange Program between China and the Netherlands, by the National Basic Research Program (No. 2010CB934603) of China, Ministry of Science and Technology of China, by the National Natural Science Foundation of China under Grant No. 50701045, and by the Hong Kong Polytechnic University Postdoctoral Fellowships Scheme (G-YX3 V).

Keywords

Magnetic properties
Nanoparticles
Rare-earth metals
Size effect

Access to Document

10.1007/s11051-010-0108-y

Cite this

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title = "Magnetic properties of Dy nanoparticles and Al2O 3-coated Dy nanocapsules",

abstract = "Dy2O3-coated Dy nanoparticles and Al 2O3-coated Dy nanocapsules, with Dy cores with the average size of 3.6 and 17.6 nm, respectively, are synthesized by arc-discharge technique. The transition from ferromagnetism to antiferromagnetism absents in the Dy nanoparticles, due to that its average core size of 3.6 nm is smaller than the helix period of Dy. The temperature of the superparamagnetism- antiferromagnetism transition in the Dy nanocapsules increases abnormally to 105 K, while the N{\'e}el temperature decreases to 150 K. The magnetic-entropy change (-ΔSm) of the Dy nanoparticles rapidly increases with decreasing temperature. For Al2O3-coated Dy nanocapsules, -ΔSm reaches 15.2 J kg-1K-1 at 7.5 K, due to the existence of superparamagnetism, and a peak (5.2 J kg-1K -1) appears at 105 K due to the superparamgantism-antiferromagnetism transition, and -ΔSm exceeds 2 J kg-1K-1 in the temperature range from 7.5 to 105 K, for a field change from 1 to 5 T.",

keywords = "Magnetic properties, Nanoparticles, Rare-earth metals, Size effect",

author = "Liu, {X. G.} and Or, {S. W.} and B. Li and Ou, {Z. Q.} and L. Zhang and Q. Zhang and Geng, {D. Y.} and F. Yang and D. Li and E. Br{\"u}ck and Zhang, {Z. D.}",

year = "2011",

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doi = "10.1007/s11051-010-0108-y",

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T1 - Magnetic properties of Dy nanoparticles and Al2O 3-coated Dy nanocapsules

AU - Liu, X. G.

AU - Or, S. W.

AU - Li, B.

AU - Ou, Z. Q.

AU - Zhang, L.

AU - Zhang, Q.

AU - Geng, D. Y.

AU - Yang, F.

AU - Li, D.

AU - Brück, E.

AU - Zhang, Z. D.

PY - 2011/3

Y1 - 2011/3

N2 - Dy2O3-coated Dy nanoparticles and Al 2O3-coated Dy nanocapsules, with Dy cores with the average size of 3.6 and 17.6 nm, respectively, are synthesized by arc-discharge technique. The transition from ferromagnetism to antiferromagnetism absents in the Dy nanoparticles, due to that its average core size of 3.6 nm is smaller than the helix period of Dy. The temperature of the superparamagnetism- antiferromagnetism transition in the Dy nanocapsules increases abnormally to 105 K, while the Néel temperature decreases to 150 K. The magnetic-entropy change (-ΔSm) of the Dy nanoparticles rapidly increases with decreasing temperature. For Al2O3-coated Dy nanocapsules, -ΔSm reaches 15.2 J kg-1K-1 at 7.5 K, due to the existence of superparamagnetism, and a peak (5.2 J kg-1K -1) appears at 105 K due to the superparamgantism-antiferromagnetism transition, and -ΔSm exceeds 2 J kg-1K-1 in the temperature range from 7.5 to 105 K, for a field change from 1 to 5 T.

AB - Dy2O3-coated Dy nanoparticles and Al 2O3-coated Dy nanocapsules, with Dy cores with the average size of 3.6 and 17.6 nm, respectively, are synthesized by arc-discharge technique. The transition from ferromagnetism to antiferromagnetism absents in the Dy nanoparticles, due to that its average core size of 3.6 nm is smaller than the helix period of Dy. The temperature of the superparamagnetism- antiferromagnetism transition in the Dy nanocapsules increases abnormally to 105 K, while the Néel temperature decreases to 150 K. The magnetic-entropy change (-ΔSm) of the Dy nanoparticles rapidly increases with decreasing temperature. For Al2O3-coated Dy nanocapsules, -ΔSm reaches 15.2 J kg-1K-1 at 7.5 K, due to the existence of superparamagnetism, and a peak (5.2 J kg-1K -1) appears at 105 K due to the superparamgantism-antiferromagnetism transition, and -ΔSm exceeds 2 J kg-1K-1 in the temperature range from 7.5 to 105 K, for a field change from 1 to 5 T.

KW - Magnetic properties

KW - Nanoparticles

KW - Rare-earth metals

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