Structural in situ studies of shape memory alloy (SMA) Ni-Ti thin films

Ni-Ti SMA thin films formed by sputtering have been attracting great interest as powerful actuators in micro-electromechanical systems (MEMS) such as micro-valves, micro-fluidic pumps and micro-manipulators. Successful implementation of Ni-Ti micro-actuators requires a good understanding of the relationship among processing, microstructure and properties of Ni-Ti thin films. At the ROssendorf BeamLine (ROBL-CRG) at ESRF, we carried out a series of experiments that clearly illustrate the benefit of in situ studies, not only during annealing, but also during sputtering. The in situ sputtering experiments during film growth were performed using a magnetron sputter deposition chamber installed into the six-circle diffractometer of the materials research station. This facility allowed us to follow, almost in “real time”, the structural evolution of the deposited thin films as a consequence of changing deposition parameters.