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Expanding the tunability and applicability of exchange-coupled/decoupled magnetic nanocomposites
Materials Chemistry Frontiers ( IF 7 ) Pub Date : 2020-02-28 , DOI: 10.1039/c9qm00713j
Cecilia Granados-Miralles 1, 2, 3, 4, 5 , Adrián Quesada 1, 2, 3, 4, 5 , Matilde Saura-Múzquiz 6, 7, 8, 9, 10 , Henrik L. Andersen 6, 7, 8, 9, 10 , José F. Fernández 1, 2, 3, 4, 5 , Mogens Christensen 6, 7, 8, 9, 10
Affiliation  

CoFe2O4/Co–Fe magnetic composites are usually prepared through partial reduction of CoFe2O4, which often yields monoxides (i.e., FeO, CoO) as secondary phases. Since these compounds are paramagnetic at ambient conditions, the presence of a small amount of monoxide is generally downplayed in the literature, and the possible effects on the magnetic properties are simply ignored. However, the present study shows that even a low concentration of monoxide results in decoupling of the soft and hard magnetic phases, which inevitably leads to a deterioration of the magnetic properties. Additionally, it is confirmed that a partial reduction of CoFe2O4 is a suitable method to produce CoFe2O4/Co–Fe nanocomposites, provided that the treatment is well controlled with respect to duration, temperature and flow of reductant. A monoxide-free nanocomposite was produced and its magnetic properties evaluated both at room and low temperature. Our model system exemplifies the potential of exchange-coupling (and decoupling) as a tool to tune the magnetic properties of a material within a relatively wide range of values, thus widening its spectrum of potential applications.

中文翻译:

扩展交换耦合/解耦磁性纳米复合材料的可调性和适用性

通常通过部分还原CoFe 2 O 4来制备CoFe 2 O 4 / Co-Fe磁性复合材料,这通常会产生一氧化碳(FeO,CoO)作为第二相。由于这些化合物在环境条件下是顺磁性的,因此文献中通常会淡化少量一氧化碳的存在,而对磁性的可能影响则被简单地忽略了。但是,本研究表明,即使一氧化碳浓度低,也会导致软磁性相和硬磁性相的解耦,这不可避免地导致磁性能下降。另外,证实了CoFe 2 O 4的部分还原。是一种生产CoFe 2 O 4 / Co-Fe纳米复合材料的合适方法,只要在还原剂的持续时间,温度和流量方面对处理进行了很好的控制即可。产生了无一氧化碳的纳米复合材料,并在室温和低温下对其磁性能进行了评估。我们的模型系统举例说明了交换耦合(和去耦)的潜力,该工具可以在相对宽的值范围内调整材料的磁性能,从而扩大了其潜在应用范围。
更新日期:2020-02-28
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