Chemical conditions and magnetic properties of different type of heterodimers or core@shell nano particles obtained by thermal decomposition

Full text: Nano heterostructures combining noble metal-ferrite in the form of either dimer, core-shell or other are interesting bifunctional materials and possess interesting optical and magnetic properties. They have enormous potential in biomedical applications such as hyperthermia treatment, magnetic resonance imaging contrast agents, magnetic separation. Controlling the morphology as well structure of these bifunctional systems (heterodimer, flower like, satellite like of core-shell) where a metallic like Ag or Au component attached or surrounded by magnetic counterpart is really a challenging task from chemistry as well as technological point of view. Thermal decomposition of metallic precursor in a high boiling point organic solvents is an effective way with good flexibility to control and tune the size, shapes through controlling the various synthesis conditions such as amount of starting metallic precursor, heating rate, refluxing temperature, surfactant ratio (oleylamine/oleic acid ) etc. On the other hand, magnetic properties are strongly dependent to shape and and sizes of obtained nanostructures. In the present work we will show various examples of how, the above mentioned conditions, allows to finely tune the shape from a heterodimer type nanoparticles (with 10 nm to 40 nm silver nano particles 10 nm to 20 nm magnetite nanoparticles) to more complex like flower type or satellite like with different sizes/shapes. Finally we will discuss the role of various synthesis conditions and some of important structural/magnetic properties of well-defined core shell nanoparticles based on Ag-Fe₃O₄ through X-rays diffraction (XRD), transmission electron microscopy (TEM), and SQUID magnetometry technique. (author)