Affiliations: [a] Graduate School of Science and Engineering, Ehime
University, Matsuyama, Japan | [b] Department of Environmental Materials Engineering,
Niihama National College of Technology, Niihama, Japan | Leibniz University of Hannover, Hannover, Germany | University of Pavia, Pavia, Italy | University of Padua, Padua, Italy
Correspondence:
[*]
Corresponding author: Hiromichi Aono, Graduate School of Science
and Engineering, Ehime University, Matsuyama 790-8577, Japan. Tel.: +81 89 927
9856; Fax: +81 89 927 9856; E-mail: [email protected]
Abstract: Nano-sized superparamagnetic
Y_{3}Fe_{5}O_{12}
ferrite having a high heat generation ability in an AC magnetic field was
prepared by physical bead milling. The highest heat ability in the AC magnetic
field was for the fine
Y_{3}Fe_{5}O_{12}
powder with a 16-nm crystallite size (the samples were milled for 4 h using 0.1
mm� beads). The main reason for the high heat generation property of the
milled samples was ascribed to an increase in the Néel relaxation of the
superparamagnetic material. For the samples milled for 4 h using 0.1 mm�
beads, the heat generation ability (W·g^{-1}) was
estimated using a 3.58 × 10^{-4} · f·
H^{2} frequency (f/kHz) and the magnetic field
(H/kA·m^{-1}), which is the highest reported value of
superparamagnetic materials. Furthermore,
Y_{3}Fe_{5}O_{12}
microspheres having a 20–32 μm diameter range were prepared by a spray
dryer using the bead-milled nano-sized particles.
Keywords: Y[TeX:] _{3}Fe[TeX:] _{5}O[TeX:] _{12}
, AC magnetic field, thermal coagulation therapy, nano particle, bead milling
