Characterization of Nanostructure of Fe7Pd3 Nano-rods and Nano-helices

The phase transformation behavior of ferromagnetic shape memory alloy (FSMA) Fe7Pd3 (hereafter, FePd) in bulk form has been well studied, but that of "nano-sized FePd" has NOT been studied despite that the research activities on developing nanorobotics based on FePd are now emerging. Two actuation mechanisms associated with FePd are considered effective in designing FePd based nanoactuators; (1) variant rearrangement in 100% martensite phase under applied constant magnetic field and (2) hybrid mechanism composed of chain-reactions, applied magnetic gradient, magnetic force ,stress-induced martensite transformation from stiff austenite to soft martensite, resulting in large displacement at fast speed. The key stimuli of such phase transformation are stress (?), temperature (T) and magnetic field (H). Applied magnetic field or gradient is related to the stress induced in a FePd sample. Thus, the most important phase transformation is realized in?the ? – T phase transformation diagram. This EMSL proposal is aimed at establishing the ?? – T phase transformation diagram of “nano-sized” FePd samples, namely nano-rods and nano-helices. To this end, we propose three tasks; Task-1 : TEM/Electron-beam study on single FePd nano-rod and nanohelix, at room temperature and at – 150 C with aim of determining the lattice parameters of austenite (FCC, lattice parameter is a0), and those of martensite (FCT, a and c), Task-2: Demonstration of FePd nanohelix shrinkage under increasing magnetic field by increasing tilting angle of TEM sample holder, and Task-3: X-ray diffraction of period grating to obtain “X-shaped image” which will provide us with the geometrical parameters of nano-helix FePd, helical pitch and helical angle.
Possible applications of nano-rods and nano-helices of FePd are (i) the electrodes of sensors and energy-harvesting devices and (ii) nanorobotics for cancer diagnosis and treatment where the FePd helix based actuators can be propelled under magnetic navigation and upon arrival at cancer cell sites, they can be actuated to make apoptotic cell deaths by the mechanically induced stress loading.