1. Fabrication and Properties of MSMA Thin Films Hierarchical Manufacturing and Modeling for Phase Transforming Active Nanostructures D.C. Lagoudas a, K. Gall b, I. Karaman c, X. Zhang c, J. Kameoka d a Department of Aerospace Engineering, Texas A&M University, College Station, Texas 77843-3141; b School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0250; c Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843-3123; d Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843-3128 Overall Concept Understand the effect of nanoscale manufacturing on reversible martensitic phase transformations Develop low-cost and easily scalable nanomanufacturing techniques that will allow fabrication of shape memory alloy (SMA) and magnetic shape memory (MSMA) alloy nanowires Fabricate higher scale structures and devices from nanowires and hybrid thin films Use multiscale modeling framework to guide the fabrication process, reveal fundamental multi-scale physical phenomena in reversible phase transformation, and aide design of higher scale devices Fabrication of nanofiber membrane for protein detection Project Objectives Fabrication of Monolithic and Hybrid SMA and MSMA Nanowire Modeling In-21at%Tl bulk and nanowires Developing new potentials based on ab initio calculations Graduate a diverse group of students prepared for research on nanotechnology with an interdisciplinary and global outlook Motivate undergraduates, particularly those from underrepresented groups, to continue to graduate school and research careers Educate undergraduate and K-12 students and teachers on technology, its benefits, and to communicate the excitement of discovery of science Educational Goals Nanowire Fabrication Procedure Indium-Thallium (In-21at%Tl) Nanowires Various diameters of In-21at%Tl nanowires fabricated (750nm, 380nm, 280nm, 70nm, 33nm). For nanowires of diameters >70nm, twins observed at room temperature along entire length of nanowires Anodized Aluminum Oxide (AAO) Template (Empty) Filled AAO template after extrusion In-21at%Tl Nanowires in Cross-Section of AAO 1 2 3 12 3 TEM dark field image of 200nm diameter nanowire showing BCT twins at room temperature TEM Dark field image of 70nm diameter nanowire showing BCT twins at room temperature TEM Dark field image of 70nm diameter nanowire with constant crystal structure at 100°C TEM Dark field image of 33nm diameter nanowire at room temperature For 70nm diameter nanowires, reversible phase transformation observed from BCT martensite to FCC austenite For 33nm diameter nanowires, SAED patterns indicate FCC crystal structure (austenite) at room temperature Selected Area Electron Diffraction (SAED) patterns of 33nm diameter nanowire at room temperature Multiscale Modeling Framework and Simulation Multilayer twinned B19’ Surface energy will reduce as twin width increases Agree well with the experimental observation Compared with shuffling to B19 one layer of atoms out of two layers shuffling two layers of atoms out of four layers Fabricate In-21at%Tl nanowires of smaller diameter Fabricate NiMnCoIn nanowires from produced thin films Future Work Mechanical Arm Pressing Chamber Hydraulic Jack Mold containing template and thin film Magnetron sputtering system for multilayer film depositions. The system has four magnetron guns capable of DC and RF sputtering and is able to obtain a base pressure of 10 -8 Torr or better. A load lock is attached to the system to increase the throughput of the system. Sputtering System NiMnCoIn Thin Films DSC curve of an as deposited, amorphous freestanding Ni 50 Co 6 Mn 38 In 6 film. The film was heated/cooled/heated at a rate of 80 °C/min. DSC curves of crystallization process in freestanding Ni 50 Co 6 Mn 38 In 6 films heated linearly at different rates. The effective crystallization energy was calculated to be 86.59 kJ mol -1. NiMnGa Thin Films NiMnGa Thin Films were deposited on several substrates. Mn-rich target with the composition of Ni 49.5 Mn 30 Ga 20.5 was used. The composition was tailored by varying the deposition power. The as-deposited films were partly crystalline as seen in the xrd pattern RT Above A f Below M f The DSC plot shows reversible martensite to austenite phase transformation As-deposited film shows grains with needle shaped texture indicating martensite, distributed in a seemingly amorphous matrix. Above A f, the diffraction pattern shows a significant change in SADP along with grain growth. Change in SADP was again observed when cooled below M f Nanoscale Martensitic Transformation Mechanisms in NiTi Fabrication of Nanofiber Membrane for Protein Detection Solution: a mixture of spin on glass coating (SOG), polyvinylpyrrolidone (PVP), and butanol. Solution concentration: PVP 0.04 g/ml, SOG:butanol = 4:1 in volume ratio. Processing parameters: feeding rate: 8 ul/min, applied voltage: 7 kV, deposition distance: 5 cm, heating temperature: 500 ° C for 12h. PVP was removed during the heating. Resultant silica membrane was composed of nanofiber with ~100 nm in diameter. Electrospinning of Silica Nanofiber Membrane Performance of Protein Detection SEM image of silica spun nanofibers Schematic of nanofiber membrane protein detector Random-distributed electrospun nanofibers formed a porous membrane. The membrane is incorporated in the layered structure of the detector. The sensitivity is improved due to the small diameter of nanofibers and the resultant extremely large surface area to volume ratio. The detection limit is 32 times lower than traditional 96-well enzyme-linked immunosorbent assay (ELISA). The detection time is 1h compared to ELISA’s 1 day