TY - JOUR
T1 - Magnetic Core-Size Distribution of Magnetic Nanoparticles Estimated from Magnetization, AC Susceptibility, and Relaxation Measurements
AU - Elrefai, Ahmed L.
AU - Sasayama, Teruyoshi
AU - Yoshida, Takashi
AU - Enpuku, Keiji
N1 - Funding Information:
ACKNOWLEDGMENT This work was supported in part by the Strategic Promotion of Innovative Research and Development, Japan Science and Technology Agency, and in part by Grant-in-Aid for Scientific Research (S), Japan Society for the Promotion of Science under Grant 15H05764.
PY - 2017/11
Y1 - 2017/11
N2 - The magnetic core-size distribution of magnetic nanoparticles (MNPs) was estimated from three independent measurements, i.e., magnetization, ac susceptibility (ACS), and magnetic relaxation (MRX). First, distribution of magnetic moment m in MNP sample was estimated by analyzing the static magnetization (M - H) curve of the MNP sample in suspension. Next, distribution of anisotropy energy E was estimated by analyzing the ACS of immobilized MNP sample measured from 10 Hz to 1 MHz. The ACS measurement in much lower frequency range was substituted by the MRX measurement. MRX of immobilized MNP sample was measured from 2 to 104 s, corresponding to the frequency range from 10-4 to 0.5 Hz in ACS measurement. The relaxation curve was analyzed using a newly developed analytical method to estimate the E distribution of the MNPs in the range of large E values. Then, the estimated distributions of m and E were transferred to the distributions of magnetic core size. Core-size distributions obtained from m and E distributions reasonably agreed with each other. Namely, we obtained similar core-size distribution from static and dynamic properties of MNP sample, confirming the validity of the present method. Therefore, the present method can be useful to estimate the core-size distribution of MNP sample.
AB - The magnetic core-size distribution of magnetic nanoparticles (MNPs) was estimated from three independent measurements, i.e., magnetization, ac susceptibility (ACS), and magnetic relaxation (MRX). First, distribution of magnetic moment m in MNP sample was estimated by analyzing the static magnetization (M - H) curve of the MNP sample in suspension. Next, distribution of anisotropy energy E was estimated by analyzing the ACS of immobilized MNP sample measured from 10 Hz to 1 MHz. The ACS measurement in much lower frequency range was substituted by the MRX measurement. MRX of immobilized MNP sample was measured from 2 to 104 s, corresponding to the frequency range from 10-4 to 0.5 Hz in ACS measurement. The relaxation curve was analyzed using a newly developed analytical method to estimate the E distribution of the MNPs in the range of large E values. Then, the estimated distributions of m and E were transferred to the distributions of magnetic core size. Core-size distributions obtained from m and E distributions reasonably agreed with each other. Namely, we obtained similar core-size distribution from static and dynamic properties of MNP sample, confirming the validity of the present method. Therefore, the present method can be useful to estimate the core-size distribution of MNP sample.
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U2 - 10.1109/TMAG.2017.2700480
DO - 10.1109/TMAG.2017.2700480
M3 - Article
AN - SCOPUS:85032988283
VL - 53
JO - IEEE Transactions on Magnetics
JF - IEEE Transactions on Magnetics
SN - 0018-9464
IS - 11
M1 - 7917306
ER -