The investigators will undertake a program of research on the development of shape memory and emerging ferromagnetic shape memory materials for the production of motion at small scales. These materials spontaneously undergo a martensitic (diffusionless, structural) phase transformation with a change of shape. In the ferromagnetic shape memory materials, the shape change can be triggered by a remotely applied magnetic field. Because of their exceptionally high work output per unit volume, and the unusually large shape changes that are predicted to be possible in single crystal thin films, these materials are good candidates for nanoscale motors. The investigators will develop theoretical models and computational predictions for nanoscale motors that move, place, orient, actuate, and propel. A program of molecular beam epitaxial growth of NiTi films will be initiated, and the predicted designs will be put into practice on single crystal thin films of NiTi and Ni2MnGa. The research includes a fundamental theoretical/ computational/ experimental study of the behavior of phase transformation and the shape memory effect at small scales, resting on the study of the martensitic phase transformation in a sequence of specimens of smaller and smaller size. Emerging multiscale mathematical methods, expanded to atomic scale, will play a key role in guiding nanoactuator design.
The production of well defined movements of objects at the nanoscale is a critical component of the emerging field of nanotechnology. This underlies the development of nanorobots, plays a crucial role in optical devices and the placement and orientation of sensors, and is an enabling component of devices that foster the interaction between the physical world and the fundamental processes of biology. The production of well defined motions and forces at small scales is particularly hampered by the dominance of interfacial and viscous forces at these scales and the destabilizing effects of random Brownian motions. The shape memory materials proposed by the investigators for use at these scales promise to overcome these impediments to well defined small-scale motion. As an underlying technology for several emerging fields, the research directly supports US strategic goals in materials science, nanotechnology, and national security.
