A Study Of Measurement Of Mechanic And Magnetic Properties Of Self Assembled Film Of Fe/Fe₃O₄ Nano Particles By Atomic Force Microscopy

The magnetic nanoparticles play an increasingly important role in the field of biomedical applications thanks to their small size good biocompatibility,electrical and magnetic properties.In addition,films assembled by magnetic nanoparticles are considered to be very promising platforms for biomedical applications such as biocompatible scaffold properties enhancement for cellular adhesion and growth in bone disorder and implantable devices for tissue engineering.However,the precise measurement of mechanical and magnetic properties of assembled magnetic nanoparticles remains a challenge.Due to the small size of nanoparticles,the measurement should be effective in nanoscale.Owing to nanosize AFM tip,the mechanical and magnetic properties of assembled nanoparticles can be measured at the local position with nanoscale resolution.Therefore,considerable attentions have been focused on the mechanical and magnetic aspects of the magnetic nanoparticles assembled films by AFM,MFM and some efforts have been carried out as follows:First,the Fe@Fe₃O₄ nanoparticles coated by oleylamine were synthesized by hydrothermal decomposition method.Then,the Fe@Fe₃O₄ nanoparticles were self-assembled into films on mica by solvent evaporation method under two specific conditions?i?under?200mT?external magnetic field?ii?without any external magnetic field.The polycrystalline of Fe@Fe₃O₄were confirmed by transmission electron microscopy?TEM?and scanning electron microscope?SEM?.The mechanic and magnetic properties of assembled film was measured by Agilent 5500?Agilent,Chandler,AZ?“closed loop”AFM system,with a piezoelectric sensor?Agilent?,using AAC mode for measuring mechanic properties,in the air and at room temperature,in a non-contact mode with Si cantilevers of an NSC18/ALBS with a nominal tip radius of less than 10nm radius of curvature and 20-25?m height.The resonant frequencies of the tip were about 220 kHz,while the magnetic measurements were carried out by using magnetic coated cantilever,having 8nm radius of curvature and 0.1N/m spring constant value.The Young's modulus of the assembled film was calculated by the Hertz model.This thesis focuses on the preparation of LBL assembled film of Fe@Fe₃O₄nanoparticles in different condition?with and without applying external magnetic field?and analyzing the mechanic and magnetic properties of these assembled film.After measuring the magnetic effect of both films we concluded from our results that the magnetic film prepared under 200mT external magnetic field shows greater magnetic strength as compare to the film which we prepare without any external magnetic field.