Usov Nikolai A, Nesmeyanov Mikhail S, Gubanova Elizaveta M, Epshtein Natalia B
National University of Science and Technology «MISIS», 119049, Moscow, Russia.
Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108480, Troitsk, Moscow, Russia.
Beilstein J Nanotechnol. 2019 Jan 29;10:305-314. doi: 10.3762/bjnano.10.29. eCollection 2019.
The low frequency hysteresis loops and specific absorption rate (SAR) of assemblies of magnetite nanoparticles with cubic anisotropy are calculated in the diameter range of = 20-60 nm taking into account both thermal fluctuations of the particle magnetic moments and strong magneto-dipole interaction in assemblies of fractal-like clusters of nanoparticles. Similar calculations are also performed for assemblies of slightly elongated magnetite nanoparticles having combined magnetic anisotropy. A substantial dependence of the SAR on the nanoparticle diameter is obtained for all cases investigated. Due to the influence of the magneto-dipole interaction, the SAR of fractal clusters of nanoparticles decreases considerably in comparison with that for weakly interacting nanoparticles. However, the ability of magnetic nanoparticle assemblies to generate heat can be improved if the nanoparticles are covered by nonmagnetic shells of appreciable thickness.
考虑到纳米颗粒磁矩的热涨落以及纳米颗粒分形簇集合体中的强磁偶极相互作用，计算了立方各向异性磁铁矿纳米颗粒集合体在直径范围为20 - 60 nm时的低频磁滞回线和比吸收率（SAR）。对具有复合磁各向异性的稍长形磁铁矿纳米颗粒集合体也进行了类似计算。在所研究的所有情况下，均获得了SAR对纳米颗粒直径的显著依赖性。由于磁偶极相互作用的影响，与弱相互作用纳米颗粒相比，纳米颗粒分形簇的SAR显著降低。然而，如果纳米颗粒被相当厚度的非磁性壳层覆盖，则磁性纳米颗粒集合体的发热能力可以得到改善。
