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首页> 外文期刊>Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics >AC magnetic field regulated in-vivo switch of Hf-substituted magnetite (HfxFe3-xO4, 0.01 = x = 0.8) nanoparticles
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AC magnetic field regulated in-vivo switch of Hf-substituted magnetite (HfxFe3-xO4, 0.01 = x = 0.8) nanoparticles

机译：Hf取代磁铁矿（HfxFe3-xO4，0.01 <= x <= 0.8）纳米粒子的交流磁场调节的体内开关

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摘要

We report the structural and magnetic behavior of HfxFe3-xO4 (0.01 <= x <= 0.8) magnetic nanoparticles. Such studies are lacking in the literature. XRD patterns after Rietveld refinement for all the samples confirm the formation of single phase inverse spinel structure. The refined structure data suggests that Hf occupies only octahedral sites at lower concentration (x <= 0.2) but get distributed to tetrahedral sites for x >= 0.4 along with these. Accordingly, a continuous change in the lattice parameter was observed. The morphology of particles was nearly spherical and the size was found to be in the range of 10-30 nm. The electron diffraction patterns support formation of cubic spinel structure. X-ray photoelectron spectroscopy (XPS) studies suggest that the samples contain only Fe2+, Fe3+ and Hf4+ ions. The elemental mapping for Fe and Hf for the samples by electron probe micro analyzer (EPMA) also confirm their presence. The saturation magnetization (M-S), remnant (Mr) and coercivity (H-C) values were found to be 51.07 A m(2)/kg, 0.98 A m(2)/kg and 1.7 mT, respectively for x = 0.06. However, with increased Hf-concentration, a continuous decrease in the MS value was observed. The value of Mossbauer parameters like hyperfine field (BHF) and isomer shift (delta) conform the distribution of Hf cations at two aforesaid sites established by Rietveld analysis also. Co-existence of ferrimagnetic and superparamagnetic states was established by Mossbauer spectra as well as from the nature of hysteresis loop. Despite their higher magnetization values and their Curie temperature (T-C) higher than 325 degrees C, almost all the samples displayed stabilization of temperature near 50 degrees C during hyperthermia experiment. The stabilization of temperature was found to be a function of concentration of Hf in Fe3O4 as well as of the amplitude and frequency of the field. Such a stabilization of temperature near therapeutic temperature during magnetic hyperthermia is similar to that of our earlier observations for ZrxFe3-xO4 (0.01 <= x <= 1.0) nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.
机译：我们报告HfxFe3-xO4（0.01 <= x <= 0.8）磁性纳米粒子的结构和磁性行为。文献中缺乏此类研究。 Rietveld精修后所有样品的XRD图谱证实了单相反尖晶石结构的形成。精炼的结构数据表明，Hf仅在较低浓度下（x <= 0.2）占据八面体位点，而与之一起分布在x> = 0.4的四面体位点。因此，观察到晶格参数的连续变化。颗粒的形态几乎为球形，并且发现尺寸在10-30nm的范围内。电子衍射图支持立方尖晶石结构的形成。 X射线光电子能谱（XPS）研究表明，样品仅包含Fe2 +，Fe3 +和Hf4 +离子。电子探针微分析仪（EPMA）对样品中Fe和Hf的元素映射也证实了它们的存在。发现对于x = 0.06，饱和磁化强度（M-S），残余（Mr）和矫顽力（H-C）值分别为51.07 A m（2）/kg、0.98 A m（2）/ kg和1.7 mT。但是，随着Hf浓度的增加，观察到MS值连续下降。 Mossbauer参数的值，如超精细场（BHF）和异构体位移（δ），也符合Rietveld分析建立的上述两个位置处Hf阳离子的分布。铁磁状态和超顺磁状态的共存是通过Mossbauer光谱以及磁滞回线的性质建立的。尽管其较高的磁化强度值和居里温度（T-C）高于325摄氏度，但在高温实验中，几乎所有样品的温度都稳定在50摄氏度附近。发现温度的稳定是Fe3O4中Hf浓度以及磁场幅度和频率的函数。磁热疗中接近治疗温度的温度稳定与我们先前对ZrxFe3-xO4（0.01 <= x <= 1.0）纳米粒子的观察类似。 （C）2016 Elsevier B.V.保留所有权利。

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