Abstract Cobalt ferrite particles with homogeneous microstructure have been prepared encased in MCM-41 (Mobil Composition Matter) and SBA-15 (Santa Barbara Amorphous) silica mesoporous structures. In addition, it was possible to obtain ferrite nanowires once the silica matrix was dissolved. The variety of samples prepared has allowed to deeply analyze the matrix effect in the magnetic behavior of these particles that behave as superparamagnetic at room temperature. It was found at 5 K, a drastic magnetic hardening of the encased ferrite particles due to the employment of such matrices, while no matrix effect was observed at 250 K.

中文翻译：

---

CoFe 2 O 4 纳米粒子中的超顺磁性：依赖于介质的集体磁性行为的一个例子

摘要 已经制备了具有均匀微观结构的钴铁氧体颗粒，其包裹在 MCM-41（美孚成分物质）和 SBA-15（圣巴巴拉无定形）二氧化硅介孔结构中。此外，一旦二氧化硅基质溶解，就有可能获得铁氧体纳米线。制备的各种样品允许深入分析这些在室温下表现为超顺磁性的颗粒的磁性行为中的基质效应。发现在 5 K 时，由于使用此类基质，包裹的铁氧体颗粒会发生剧烈的磁硬化，而在 250 K 时未观察到基质效应。