Barrera Gabriele, Allia Paolo, Tiberto Paola
INRIM, Advanced Materials Metrology and Life Sciences, Strada delle Cacce 91, I-10135 Torino, Italy.
Nanoscale. 2021 Feb 25;13(7):4103-4121. doi: 10.1039/d0nr07397k.
Rate equations are used to study the dynamic magnetic properties of interacting magnetite nanoparticles viewed as double well systems (DWS) subjected to a driving field in the radio-frequency range. Dipole-dipole interaction among particles is modeled by inserting an ad-hoc term in the energy barrier to simulate the dependence of the interaction on both the interparticle distance and degree of dipole collinearity. The effective magnetic power released by an assembly of interacting nanoparticles dispersed in a diamagnetic host is shown to be a complex function of nanoparticle diameter, mean particle interdistance and frequency. Dipolar interaction markedly modifies the way a host material is heated by an assembly of embedded nanoparticles in magnetic hyperthermia treatments. Nanoparticle fraction and strength of the interaction can dramatically influence the amplitude and shape of the heating curves of the host material; the heating ability of interacting nanoparticles is shown to be either improved or reduced by their concentration in the host material. A frequency-dependent cut-off length of dipolar interactions is determined and explained. Particle polydispersity entailing a distribution of particle sizes brings about non-trivial effects on the heating curves depending on the strength of dipolar interaction.
速率方程用于研究被视为双阱系统（DWS）的相互作用磁铁矿纳米颗粒在射频范围内的驱动场作用下的动态磁特性。通过在能垒中插入一个临时项来模拟颗粒间的偶极 - 偶极相互作用，以模拟相互作用对颗粒间距离和偶极共线程度的依赖性。分散在抗磁基质中的相互作用纳米颗粒集合释放的有效磁功率被证明是纳米颗粒直径、平均颗粒间距和频率的复杂函数。在磁热疗中，偶极相互作用显著改变了基质材料被嵌入的纳米颗粒集合加热的方式。纳米颗粒分数和相互作用强度会显著影响基质材料加热曲线的幅度和形状；相互作用的纳米颗粒的加热能力被证明会因其在基质材料中的浓度而提高或降低。确定并解释了偶极相互作用的频率相关截止长度。涉及粒径分布的颗粒多分散性根据偶极相互作用的强度对加热曲线产生非平凡的影响。
