An experimental and theoretical study on the role of copper interlayers for the microstructure of NiTi thin films on graphene substratesThursday (29.09.2016) 10:15 - 10:30 Part of:
Coating planar graphene substrates with Nickel-Titanium (NiTi) results in novel microstructures. The present study explores how thin NiTi films can be deposited on graphene substrates. We deposited NiTi with thicknesses in the range of 2 to 4 microns on graphene substrates. A PVD magnetron sputter process was used for the deposition and the coated substrate was subsequently annealed at 450 °C for several minutes. Different microstructures were observed when using a copper interlayer between graphene and NiTi. These microstructures were characterized by electron microscopy, electron backscatter diffraction, and transmission electron microscopy. Our results show that grain size and grain orientations in the thin NiTi films are considerably affected by the Cu interlayer. Theoretical investigations within the density functional theory framework were used to calculate the binding energies for different orientations of NiTi on the substrates. These numerical results support the experimental findings and provide details on the interaction at the NiTi / substrate interface that may explain the special microstructure of the functional NiTi layer.