Zinc-Manganese spinel ferrites (Zn1-xMnxFe2O4) are nowadays very attractive magnetic materials for cancer diagnostic and therapy. With the help of intense ultrasonic waves, sonochemical synthesis method was used to prepare stoichiometric and chemically homogenous nanoparticles by varying the manganese content. The crystal structure along with the size and shape of the as-prepared nanoparticles were described using XRD, TEM and FT-IR techniques, while cations distribution was carefully investigated using XPS and Mössbauer spectroscopic techniques and supported with density functional theory calculations. The crystal structure study revealed the presence of a pure single cubic spinel phase, where the unit-cell and the size were observed to decrease as the manganese incorporation was increased with clear indication of cationic redistribution and degree of inversion variations. Due to the very small variation of the total energy between different configurations, the probability of formation of a mixed phase was found to be very high in such a way that the more mixed was the phase, the more stable it was. A relevant fact was the noticed quasi-systematic ionic exchange made possible by the very short reaction times and high energy offered by the ultrasonic waves. For manganese concentrations up to 60%, the systematic ionic process started by incorporating manganese ions into octahedral sites and pushing iron ions to migrate and replace those of zinc in tetrahedral sites. Such an ionic movement was of central importance for the improvement of the magnetic properties due to the establishment of super-exchange interactions. Such an ionic engineering should definitely open the way to promising applications in biomedical imaging.

中文翻译：

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具有改进磁性能的锌锰铁氧体的超声化学合成


锌锰尖晶石铁氧体 （Zn1-xMnxFe2O4） 是当今非常有吸引力的癌症诊断和治疗磁性材料。在强超声波的帮助下，采用声化学合成方法通过改变锰含量制备化学计量和化学均质的纳米颗粒。使用 XRD、TEM 和 FT-IR 技术描述晶体结构以及制备的纳米颗粒的大小和形状，同时使用 XPS 和 Mössbauer 光谱技术仔细研究阳离子分布，并得到密度泛函理论计算的支持。晶体结构研究揭示了纯单立方尖晶石相的存在，其中观察到晶胞和尺寸随着锰掺入的增加而减小，并清楚地表明阳离子再分布和反转变化的程度。由于不同构型之间总能量的变化非常小，因此发现形成混合相的可能性非常高，因此相混合越多，它就越稳定。一个相关的事实是，由于超声波的反应时间非常短，能量很高，因此引起了人们的注意的准系统离子交换。对于高达 60% 的锰浓度，系统离子过程首先将锰离子掺入八面体位点，并推动铁离子迁移并取代四面体位点中的锌离子。由于建立了超级交换相互作用，这种离子运动对于改善磁性能具有核心重要性。这样的离子工程无疑应该为生物医学成像中的有前途的应用开辟道路。